Dissertations / Theses on the topic 'Fermented milk – Sensory evaluation'

Thesis (MSc Food Sc)--Stellenbosch University, 2000.
ENGLISH ABSTRACT: Maas is a traditional fermented milk drink of the indigenous people of Southern Africa and can thus be used to uplift the nutritional status of the South African population, especially for the lower income groups. Furthermore, the problem of lactose intolerance among the Black population can also be addressed by the consumption of Maas. The objective of this study was to screen mesophylic lactic acid bacterial strains (25 in total) from the University of Stellenbosch Food Science Culture Collection for suitable metabolite production and then to produce traditional Maas with a starter culture combination that produces a distinctive acid and traditional flavour. The representative 25 single lactic acid starter strains were identified as Lactococcus lactis subsp. leetis biovar diacetylactis (12 strains), L. leetis subsp. leetis (four strains) and L. leetis subsp. cremoris (nine strains). These strains were inoculated into pasteurised full cream milk and activated for 8 h at 22°C. Pasteurised full cream milk was then inoculated with each of the activated starter strains, incubated at 22°C for 16 h and assessed for acid production abilities (pH = 4.6) under controlled time-temperature conditions. The results of this study showed that nine of the single strains, L. lactis subsp. leetis biovar diacetylactis (S1, S2, S3 and S5), L. teetis subsp. lactis (S13, S15 and S16) and two L. leetis subsp. cremoris strains (S17 and S22), produced sufficient acid, rendering them suitable for the use as starters in the production of traditional Maas. A pH range of 4.3 - 5.1 was reached by the nine single strains after 16 h at 22°C. Two-strain starter combinations were then formed by combining the most suitable single L. leetis subsp. leetis biovar diacetylactis, L. lactis subsp. lactis and L. lactis subsp. cremoris strains, respectively. From the data, it was concluded that acceptable Maas could be produced with four two-strain combinations (S3S 17, S3S22, S5S17 and S5S22). This selection was again based on suitable acid and metabolite production, as well as on sensory evaluation of the final product. These four two-strain combinations produced sufficient acid to reach a pH in the 4.6 - 4.8 range, and showed a high metabolite concentration for the most suitable compounds and formed a thick, smooth and creamy body texture after 16 h at 22°C. Three-strain combinations formed between the two-strain starter combinations and L. leetis subsp. teetis strains (813, 815 and 816), were also evaluated. With these combinations a lack of a pronounced Maas flavour was found. Thus, it was decided to add aroma producing strains of the species Leuconostoc mesenteroides subsp. dextranicum (strain L1) and L. mesenteroides subsp. citrovorum (strain L2) to the three-strain combinations. Four culture combinations (A, B, C and D) were then formed by combining the selected Leuconostoc strains (L1 and L2) with the most suitable Lactococcus strains (83,817,813 and 822). These combinations produced sufficient acid to reach the pH 4.5 - 4.6 range after 14 h at 22°C. Acetaldehyde was the major flavour metabolite formed in the Maas made with these four combinations, with concentrations ranging between 26.6 - 89.3 mg.l ̄ ¹, while other flavour metabolites (ethanol, acetone, diacetyl and 2-butanone) were present at lower concentrations. It was found that three of the four culture combinations (A, C and D) were characterised by a superior, but delicate flavour and a typical characteristic Maas body texture. Fruit flavoured Maas was subsequently prepared with the three most suitable culture combinations (A, C and D) using 11 flavours and a sensory evaluation performed. The statistically evaluated data showed that the appearance, smoothness, flavour intensity, sweetness and overall acceptability were influenced by the type of fruit flavour and the culture combination. Fruit flavour 4 (banana) was the most preferred flavour. The sensory panellists also indicated that the culture combination C gave the best overall acceptability over a three week study period. Data on the shelf-life study of natural unflavoured Maas, prepared with the three culture combinations (A, C and D), showed that the Maas still had an acceptable appearance, taste and good microbiological quality after 15 d at refrigerated temperatures.
AFRIKAANSE OPSOMMING: Maas is 'n tradisionele gefermenteerde melkdrankie onder die inheemse bevolking van Suid-Afrika en kan gebruik word om die voedingstatus van die Suid-Afrikaanse bevolking te verhoog, veral vir die laer inkomste groepe. Bowendien, kan die probleem van laktose intoleransie onder die Swart gemeenskap ook aangespreek word deur die verbruik van Maas. Die doel van hierdie studie was om enkelstam mesofiliese melksuur bakterieë (25 in totaal) van die Universiteit van Stellenbosch Voedselwetenskap Kultuur Versameling te ondersoek vir geskikte metaboliet produksie en tradisionele Maas met 'n kenmerkende suurheid en tradisionele geur met 'n geskikte kultuur kombinasie te produseer. Die toonaangewende 25 enkelstamme is Lactococcus lactis subsp. leetis biovar diacetylactis (12 stamme), L. lactis subsp. lactis (vier stamme) en L. lactis subsp. cremoris (nege stamme). Hierdie stamme was in gepasteuriseerde volroom melk geïnokuleer en geaktiveer vir 8 h teen 22°C. 'n Inokulum van die onderskeie geaktiveerde stamme is hierna in gepasteuriseerde volroom melk geplaas, vir 16 h teen 22°C geïnkubeer en hul vermoë om suur te produseer (pH = 4.6) onder beheerde tyd-temperatuur kondisies is bepaal. Die resultaat van die studie het aangedui dat nege enkelstamme, naamlik L. leetis subsp. lactis biovar diacetylactis (S1, S2, S3 en S5), L. lactis subsp. leetis (S13, S15 en S16) en twee L. leetis subsp. cremoris (S 17 en S22), geskikte suurheidsvlakke vir die produksie van Maas bereik het. 'n pH vlak van 4.3 - 5.1 is na 16 h teen 22°C deur hierdie nege enkelstamme bereik. Twee-stam kombinasies is onderskeidelik gevorm tussen die geskikte enkel L. lactis subsp lactis biovar diacetylactis, L. lactis subsp. lactis en L. lactis subsp. cremoris stamme. Die gevolgtrekking gemaak uit die data, is dat aanvaarbare Maas voorberei kan word met vier van die twee-stam kombinasies (S3S17, S3S22, S5S17 en S5S22) op grond van suurvorming, metaboliet produksie en sensoriese evaluasie. Hierdie vier kombinasies het genoegsame suur geproduseer om 'n pH vlak van 4.6 - 4.8 bereik, hoë metaboliet konsentrasies geproduseer en 'n dik, gladde en romerige tekstuur aangeneem na 16 h teen 22°C. Drie-stam kombinasies is gevorm tussen die onderskeie twee-stam kombinasies en L. lactis subsp. lactis stamme (813,815 en 816) en ook geëvalueer. Die tekort aan 'n skerp Maas geur in die drie-stam kombinasies het daartoe gelei dat Leuconostoc mesenteroides subsp. dextranicum (stam L1) en L. mesenteroides subsp. citrovorum (stam L2) bygevoeg is. Vier kultuur kombinasies (A, B, C en D) is gevorm deur die geselekteerde Leuconostoc stamme (L1 en L2) te kombineer met die mees gepaste Lactococcus stamme (83, 817, 813 en 822). Hierdie kombinasies het genoegsame suur geproduseer wat 'n pH vlak van 4.5 - 4.6 na 14 h teen 22°C bereik het. In die Maas wat met bovermelde kombinasies gemaak is, was die asetaldehied die mees geproduseerde geur metaboliet teen konsentrasies van 26.6 - 89.3 mg.l ̄ ¹. Ander geur metaboliete (etanol, asetoon, diasetiel, 2-butanoon) is in laer konsentrasies geproduseer. Daar is gevind dat drie uit die vier kultuur kombinasies (A, C en D) 'n superieur, delikate geur wat 'n tipies karakteristiek van die Maas gehad het. Vrugte gegeurde Maas geproduseer met die drie kultuur kombinasies (A, C en D) deur 11 geursels te gebruik, is sensories geëvalueer. Die statistiese geëvalueerde data het getoon dat die voorkoms, gladheid, geur intensiteit, soetheid en die algehele aanvaarbaarheid beïnvloed is deur die tipe vrugte geursels en die kultuur kombinasies. Die vrugte geursel 4 (piesang) het voorkeur geniet. Die sensoriese paneellede het ook aangedui dat kultuur kombinasie C die algehele mees aanvaarbare Maas geproduseer het oor die studie periode van drie weke. Data van die rakleeftyd van die natuurlike ongegeurde Maas wat geproduseer is met die drie kultuur kombinasies (A, C en D) het aangedui dat die Maas na 15 d by yskas temperatuur steeds 'n aanvaarbare voorkoms, smaak en goeie mikrobiologiese kwaliteit gehad het.

Thesis (MSc)--Stellenbosch University, 2002.
ENGLISH ABSTRACT: Developing countries such as South Africa are in dire need of nutritionally adequate dairy food and beverage sources that are ambient stable due to minimal access to refrigeration. One such product is Kefir, a naturally fermented milk beverage that originated in Caucasian China many centuries ago. The microorganisms responsible for fermentation of the milk are held together in a carbohydrate matrix in the form of small grains. These grains are then removed from the beverage prior to consumption, and added to fresh milk for new fermentations. This beverage holds great potential for large scale development due to the self-propagating nature of the grains, the lack of sophisticated equipment and knowledge necessary for production, and the appealing sensory characteristics of this beverage. This study was therefore performed as an initial investigation to determine the optimum fermentation conditions for large-scale grain production and optimal sensory appeal. Kefir grain production was found to be proportional to incubation temperature in the range studied (18°, 22°, 25° and 30°C), with maximum grain biomass increases of 500% for the Kefir incubated at 30°C over the 10 d trial. During fermentation of Kefir grains in milk, lactic acid and other metabolites are produced. Lactic acid results in coagulation of the milk, necessary to provide the characteristic texture and flavour of Kefir, as well as exerting a preservative effect. Lactic acid production was found to be strongly proportional to both incubation temperature and inoculum concentration. The samples containing 2% (w/v) Kefir grain inoculum concentration that were incubated at 25°C for 24 h were found to have optimum lactic acid levels for good quality Kefir (pH of 4.4 - 4.6 and TA of 1.0 - 1.15%). The other metabolites produced during Kefir fermentation are responsible for the specific flavour of Kefir, and include acetaldehyde, diacetyl, ethanol, acetone and 2-butanone. These compounds were studied using headspace gas chromatography over the fermentation period, which yielded good resolution and separation of all these compounds, however, only acetaldehyde, ethanol and acetone were found to be major metabolites in this study, These analytical results were then further compared to sensory results for key identified attributes, as obtained from a trained sensory panel, to enable recommendations for optimum fermentation conditions to be made. The studied attributes included sourness, sweetness, butteriness, creaminess, yoghurt flavour, cowiness, effervescence, yeastiness, smoothness and overall acceptability. It was apparent from this study that correlations between analytical and sensory data could be drawn, and that panellists were particularly accurate in detecting the attribute sourness resulting from the accumulated lactic acid in the Kefir. Overall acceptability also seemed to be intricately linked to the attribute creaminess, hence the regular literature references to full-cream Kefir as optimum for best sensory appeal. From this study, it was evident that Kefir with optimal sensory appeal is obtained with incubation for 18 h at moderate temperatures (22° or 25°C) and grain inoculum concentrations (0.8% w/v).
AFRIKAANSE OPSOMMING: In ontwikkelende lande soos Suid-Afrika, bestaan daar 'n groot behoefte aan voedsame suiwelprodukte wat stabiel is by kamer temperatuur aangesien 'n groot deel van die bevolking beperkte toegang tot verkoelingsfasiliteite het. Een so 'n produk is Kefir, 'n natuurlike gefermenteerde suiwelproduk wat sy oorsprong eeue gelede in China gehad het. Die mikroorganismes wat verantwoordelik is vir die fermentasie, is saamgebind in 'n koolhidraat matriks in die vorm van klein korrels. Hierdie korrels word verwyder uit die drankie voordat dit gedrink word, en word dan weer by vars melk bygevoeg vir 'n verdere fermentasie. Hierdie gefermenteerde produk het baie potensiaal vir massa-produksie, omdat die korrels natuurlik vermeerder, geen gesofistikeerde toerusting of kennis nodig is nie, en die finale produk hoogs aanvaarbare sensoriese eienskappe het. Die doel van die studie was om 'n inleidende ondersoek uit te voer om die optimum fermentasie toestande vir massakweking van korrels en die mees aanvaarbare sensoriese eienskappe te bepaal. Uit hierdie studie is gevind dat Kefirkorrel vermeerdering proporsioneel is tot die verhoging in inkubasie temperatuur in die gebied 18°, 22°, 25° en 30°C, met maksimum biomassa toenames van tot 500% vir Kefir wat vir 10 dae by 30°C geïnkubeer was. Gedurende fermentasie van Kefirkorrels in melk, word melksuur en ander metaboliete gevorm. Melksuur lei tot die verlaging van die pH van die melk, en veroorsaak stolling, wat noodsaaklik is vir die kenmerkende tekstuur en geur van Kefir, maar dien ook as 'n preserveermiddel. Daar is ook gevind dat melksuur produksie 'n direkte verband het met die inkubasie temperatuur en inokulum konsentrasie. Die monsters met Kefirkorrel inokulum konsentrasie van 2% (miv) wat vir 24 h by 25°C geïnkubeer is, het die optimale melksuur konsentrasies vir goeie kwaliteit Kefir bevat (pH van 4.4 - 4.6 en TA van 1.0 - 1.15%). Ander metaboliete wat belangrike geurkomponente van Kefir is, is asetaldehied, diasetiel, etanol, asetoon en 2-butanoon. Hierdie metaboliete is bepaal en geëvalueer met bodamp gaschromatografiese tegnieke gedurende die fermentasie, wat 'n goeie resolusie en skeiding gelewer het. In hierdie studie is slegs asetaldehied, etanol en asetoon as hoof Kefir metaboliete gevind. Die analitiese data is verder vergelyk met die sensoriese data van die hoof sensoriese komponente, soos bepaal deur 'n opgeleide sensoriese paneel, om die mees gunstigde fermentasie parameters te bepaal. Die geëvalueerde eienskappe was suurheid, soetheid, botterigheid, romerigheid, joghurt geur, koeismaak, gas inhoud, gisagtigheid, gladheid en algehele aanvaarbaarheid. Uit hierdie data is gevind dat daar wel 'n sterk korrelasie bestaan tussen die analitiese en sensoriese resultate, en dat paneellede in staat was om die suurheid, as gevolg van die gevormde melksuur, te bepaal. Algehele aanvaarbaarheid is definitief gekoppel aan romerigheid, daarom word volroommelk Kefir verkies bo die wat met afgeroomde melk berei is. Die data uit hierdie studie het ook getoon dat Kefir met optimale sensoriese eienskappe verkry is na 'n inkubasietyd van 18 h by "matige temperature" (22° of 25°C) en 'n Kefirkorrel inokulum van 0.8% (mIv).

Tese de Doutoramento em Ciências Veterinárias. Especialidade Segurança Alimentar
O omavele é um leite fermentado artesanalmente produzido pelas populações pastoris do sul e sudoeste de Angola. Os leites fermentados artesanalmente constituem uma parte importante da dieta das populações africanas e, para além de fornecerem nutrientes, têm a vantagem de se conservarem por longos períodos de tempo devido ao baixo pH e à presença de compostos que inibem o desenvolvimento tanto de microrganismos patogénicos como dos de decomposição. O processo de fabrico do omavele consiste em colocar o leite de vaca, imediatamente depois da ordenha, numa cabaça contendo ou não raízes ou cascas de plantas para acelerar a sua coagulação e a formação do “ngundi”. A fermentação decorre em cerca de 9 horas à temperatura ambiente. O objetivo do nosso estudo foi caracterizar a microbiota láctica presente no omavele de produção artesanal, para se poderem produzir fermentos que serão utilizados na produção industrial do omavele. Analisou-se a composição química e a qualidade higio-sanitária do omavele tradicional. Nas 57 amostras de omavele colhidas em diferentes localidades da província da Huíla os teores médios microbianos foram: Lactobacilos (6,8 log10 ufc/mL), Lactococos (6,24 log10 ufc/mL), Leveduras (5,82 log10 ufc/mL), Enterococos (4,48 log10 ufc/mL), Micrococos (3,74 log10 ufc/mL), Enterobactérias (3,26 log10 ufc/mL) e Aeróbios totais a 30ºC (6,31 log10 ufc/mL). A identificação genética de 141 isolados, por técnicas de biologia molecular, revelou que as espécies mais identificadas foram Lb. plantarum/Lb. pentosus (31,20%), Lb. casei/Lb. paracasei (7,09%), Lb. plantarum (4,34%), Kazachstania unispora (9,92%), Saccharomyces cerevisiae (8,51%) e Issatchenkia orientalis (8,51%). Foram selecionadas estirpes para se constituírem três fermentos (FO1, FO2 e FO3) que foram usados para a produção industrial de três leites fermentados (O1, O2 e O3), cuja avaliação microbiológica 30 dias pós-produção revelou teores de microrganismos viáveis ≥ 7 log10 ufc/mL, demonstrando uma boa capacidade de sobrevivência ao processamento industrial. Após avaliação sensorial o omavele O1 foi o eleito entre os 3 leites produzidos.
ABSTRACT - Study of lactic microbiota in fermented milk consumed in the south of Angola - The omavele is a fermented milk produced by artisan shepherd populations of the south and southwest Angola. The handmade fermented milks are an important part of the diet of African populations. In addition to providing nutrients they have the advantage of long shelf life due to the low pH and the presence of compounds that inhibit the growth of both pathogenic and spoilage microorganisms. The manufacturing process of omavele involves placing the cow’s milk, immediately after milking, in a gourd containing or not roots or bark of a plant to accelerate the coagulation and the formation of “ngundi”. Fermentation takes place in about 9 hours at room temperature. The aim of our study was to characterize the lactic microbiota present in handmade omavele, to be able to produce yeasts that will be used in the industrial production of omavele. We analyzed the chemical composition and the hygienic quality of traditional handmade omavele. In 57 omavele samples collected in different localities of Huíla province the microbial average counts were: Lactobacillus (6,8 log10 cfu/mL), Lactococci (6,24 log10 cfu/mL), Yeast (5,82 log10 cfu/mL), Enterococci (4,48 log10 cfu/mL) Micrococci (3,74 log10 cfu/mL), Enterobacteriaceae (3,26 log10 cfu /mL) and Total Aerobes at 30 ° C (6,31 log10 cfu/mL). The genetic identification of 141 isolates by techniques of molecular biology has shown that most species were Lb. plantarum / Lb. pentosus (31,20%), Lb. casei / Lb. paracasei (7,09%), Lb. plantarum (4,34%), Kazachstania unispora (9,92%), Saccharomyces cerevisiae (8,51%) and Issatchenkia orientalis (8,51%). Strains were selected to constitute three yeasts (FO1, FO2 and FO3) that were used for the industrial production of three fermented milks (O1, O2 and O3), whose microbiological evaluation 30 days after production revealed levels of viable microorganisms ≥ 7 log10 cfu/mL, demonstrating a good ability for industrial processing. After the sensory evaluation omavele O1 has been selected among the 3 milks produced.

Thesis (MSc Food Sc )--Stellenbosch University, 2000.
ENGLISH ABSTRACT: The rapid urbanisation of the African population has led to the establishment of large low-income communities in and around almost every major town and city in South Africa. Several factors prevent these people from producing or obtaining their traditional fermented milk drink, Maas (Amasi), often resulting in the occurrence of malnutrition in low-income urban African communities. A product with the potential to satisfy the demand for a fermented milk product is Kefir. Kefir, a self-carbonated fermented milk, is commonly manufactured by fermenting unpasteurised or pasteurised milk with re-usable Kefir grains. These Kefir grains consist of a combination of mainly lactic acid bacteria and yeasts. Neither Kefir, nor Kefir grains are as yet marketed in South Africa, thus creating an excellent opportunity to launch these products locally. It is often difficult for the low-income communities to obtain high quality unpasteurised or pasteurised milk, resulting in a serious health risk. The inhibitory activity of Kefir towards certain spoilage and pathogenic microorganisms was, therefore, studied. Strains of Escherichia coli, Staphylococcus aureus, Bacillus cereus, Usteria monocytogenes and Clostridium tyrobutyricum were inoculated (10 ³ - 10 ⁴ cfu.ml⁻¹ ) into pasteurised milk together with Kefir grains (18 gram per litre) and incubated at 25°C. Uninoculated milk samples and milk samples inoculated only with test organisms served as controls. Growth of all the test organisms were inhibited substantially (>-99.9%) in Kefir over the 30 h incubation period and substantial reductions in microbial log cycles were observed for many of the organisms. This coincided with a steep decrease in pH (6.57 - 4.06) and increase in titratabie acidity (0.20 - 0.72%). If Kefir is eventually marketed to low-income urban African consumers, it will have to compete with Maas and, therefore, comparative sensory testing of Kefir and Maas was conducted. The differences in the sensory properties of Kefir, 'laboratory' Maas (representing traditional Maas) and commercial Maas (containing thickener, colourants and flavourants) were determined by a trained panel. These characteristics were identified as "yeasty" and "cowy" tastes (p < 0.05), "effervescence" (p < 0.01), as well as "sourness," "creaminess" and "smoothness" (p < 0.001). The effect of different incubation temperatures (25°, 30° and 35°C) on the Kefir sensory properties was studied to simulate the effect of the large temperature variations that would be found in the dwellings of low-income African urbanites. The "sourness" and "creaminess" of the Kefir was found to increase with increase in incubation temperature but no strong off-flavours were found to develop. Sensory preference testing was conducted by consumer panels consisting of panellists of different ages and population groups to indicate whether the specific panels significantly prefer Kefir, commercial Maas or laboratory Maas. It was found that commercial Maas was significantly (p < 0.001) preferred to Kefir by young African urbanites. Adult Africans, who presumably still have traditional taste preferences, however, equally (p > 0.05) preferred Kefir and laboratory Maas, identifying this segment of the African population as the appropriate starting target market for Kefir. Kefir and laboratory Maas were also tested for preference by a wider panel consisting of people (aged between 18 and 25) representing the different population groups in South Africa. Kefir and laboratory Maas were preferred equally (p > 0.05) by all the groups. Several arguments supporting Kefir marketing to the low-income urban African population of South Africa have been identified. These include: Kefir's ease of preparation; the re-usability of Kefir grains and subsequent affordability; good packaging, distribution and storage possibilities; Kefir's acceptability by lactoseintolerant individuals; high nutritional value; the inhibitory activity of Kefir against potential spoilage and pathogenic organisms and subsequent enhanced safety and keeping ability; and Kefir's acceptable refreshing taste.
AFRIKAANSE OPSOMMING: Die toenemende verstedeliking van Swart Suid-Afrikaners het gelei tot die vestiging van groot lae-inkomste gemeenskappe in en om die meeste groot dorpe en stede. Verskeie faktore verhoed dat hierdie gemeenskappe hul tradisionele gefermenteerde melk, naamlik Maas (Amasi), self kan maak of koop. Dit lei dikwels tot wanvoeding onder lae-inkomste stedelike Swart verbruikers. Kefir het die potensiaal om te voorsien in die vraag na 'n gefermenteerde melk produk in lae inkomste stedelike Swart gemeenskappe. Kefir is 'n selfgekarboneerde, gefermenteerde melk wat vervaarding word deur die fermentasie van ongepasteuriseerde of gepasteuriseerde melk met herbruikbare Kefirkorrels. Hierdie Kefirkorrels bestaan uit 'n kombinasie van hoofsaaklik melksuurbakterieë en giste. Kefir en Kefirkorrels word glad nie in Suid-Afrika bemark nie, en bied 'n fantastiese geleentheid om hierdie produkte plaaslik bekend te stel. Dit is dikwels moeilik om hoë kwaliteit ongepasteuriseerde of gepasteuriseerde melk in lae-inkomste gemeenskappe te verkry. Die risiko om siektes deur die verbruik van hierdie melk op te doen, bestaan dus. Om hierdie rede is die inhiberende effek van Kefir teenoor spesifieke bederf- en patogeniese bakterieë bestudeer. Rasse van Escherichia coli, Staphylococcus aureus, Bacillus cereus, Usteria monocytogenes en Clostridium tyrobutyricum is geïnokuleer (10 ³ - 10 ⁴ cfu.ml⁻¹) in gepasteuriseerde melk tesame met Kefirkorrels (18 gram per liter) en geïnkubeer by 25°C. Melkmonsters wat slegs geïnokuleer is met die toetsorganismes het as kontroles gedien. Die groei van al die toetsorganismes is substansieël geïnhibeer (>-99.9%) in Kefir gedurende die 30 h inkubasieperiode. Substansiële afnames in logsiklusgetalle is waargeneem vir baie van die organismes. Dit het gepaard gegaan met 'n skerp afname in pH (6.57 - 4.06) en toename in titreerbare suurheid (0.20 - 0.72%) vir die Kefirmonsters gedurende die 30 h inkubasieperiode. lndien Kefir bemark word aan lae-inkomste stedelike Swart verbruikers sal dit moet kompeteer met Maas. Vergelykende sensoriese toetse is dus uitgevoer. Die verskille in die sensoriese eienskappe van Kefir, 'laboratorium' Maas (verteenwoordigend van tradisionele Maas) en kommersiële Maas (wat verdikker, kleur- en geurmiddels bevat) is bepaal deur 'n opgeleide paneel en geïdentifiseer as die" "gis-" en "koeismake" (p < 0.05), die "gasserigheid" (p < 0.01) asook die "suurheid", "romerigheid" en "gladheid" (p < 0.001) van die monsters. Die effek van verskillende inkubasietemperature (25°, 30° en 35°C) op die sensoriese eienskappe van Kefir is bestudeer om die effek van die groot temperatuurvariasies wat in laeinkomste behuising mag voorkom, te simuleer. Daar is bevind dat die "suurheid" en "romerigheid" van Kefir toeneem met verhoging in inkubasietemperatuur terwyl geen afsmake ontwikkel nie. Sensoriese voorkeurtoetse is deur verbruikerspanele van verskillende ouderdomme en bevolkingsgroepe uitgevoer om te bepaal of die spesifieke panele 'n beduidende voorkeur toon vir Kefir, laboratorium Maas of kommersiële Maas. Daar is bevind dat stedelike Swart jongmense kommersiële Maas beduidend (p < 0.001) bo Kefir verkies. Swart volwassenes met verwagte tradisionele smaakvoorkeure het egter Kefir en laboratorium Maas ewe veel verkies (p > 0.05). Hierdie segment van die Swart bevolking is dus die geskikte teikenmark vir die bekendstelling van Kefir. Voorkeur vir Kefir en laboratorium Maas is ook getoets deur 'n paneel (ouderdom 18 - 25 jaar) wat bestaan uit mense van verskillende bevolkingsgroepe. AI die groepe het Kefir en Maas ewe veel verkies (p > 0.05). Verskeie argumente ten gunste van die bemarking van Kefir aan lae-inkomste stedelike Swart gemeenskappe in Suid-Afrika is geïdentifiseer. Dit behels die volgende: die gerief van Kefirvervaardiging; die herbruikbaarheid van Kefirkorrels en gevolglike bekostigbaarheid; goeie verpakkings-, verspreidings- en opbergingsmoontlikhede; Kefir se aanvaarbaarheid vir laktose-intolerante individue; Kefir se hoë voedingswaarde; die inhiberende aktiwiteit wat Kefir teenoor potensiële bederf- en patogeniese organismes het en die gevolglike verhoging in veiligheid en rakleeftyd van melk; en Kefir se aanvaarbare verfrissende smaak.

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A ingestão de probióticos tem sido relatada como sendo um dos métodos mais amplamente utilizados para modular a microbiota intestinal. Curiosamente, o diabetes mellitus tipo 2 tem sido associado à disbiose e uma das possíveis vias de reestabelecer a microbiota intestinal saudável é por meio da ingestão regular de probióticos, os quais vem se destacando na indústria alimentícia. Assim, o objetivo deste estudo foi, primeiramente, desenvolver um leite fermentado de origem caprina, saborizado com suco de uva, contendo probióticos e, posteriormente, avaliar o seu efeito metabólico em diabéticos. Leites fermentados contendo ou não bactérias probióticas (Lactobacillus acidophilus La-5 e Bifidobacterium animalis subsp. lactis BB-12) foram submetidos a analises físico-químicas, microbiológicas, sensoriais, além da caracterização nutricional do produto, incluindo atividade antioxidante. O teor de compostos fenólicos totais e atividade antioxidante do leite fermentado contendo probióticos foi maior (p < 0,01) do que o leite fermentado convencional. Observou-se uma maior perda da viabilidade celular para L. acidophilus do que para o B. animalis. No entanto, a viabilidade de todas as bactérias foi adequada (> 106 UFC/ mL) até o 28o dia de armazenamento a 4 oC. Ambos os leites fermentados analisados apresentaram boas características sensoriais, não havendo diferença (p > 0,05) entre os mesmos. Um estudo duplo-cego, randomizado e placebo-controlado, incluindo 50 indivíduos diabéticos, foi desenvolvido posteriormente. Os diabéticos foram divididos em dois grupos, recebendo 120 mL/dia de uma das bebidas durante 6 semanas. Medidas antropométricas, de composição corporal, coleta de sangue e amostras fecais foram obtidos no início e ao final do estudo. A ingestão de leite fermentado contendo probióticos promoveu uma redução (p ≤ 0,05) nos níveis de frutosamina e uma tendência à redução (p = 0,07) nos níveis de hemoglobina glicada. Em ambos os grupos foram observados reduções significativas nos níveis de TNF-α e resistina e a concentração fecal de ácido acético aumentou ao final do estudo, enquanto os níveis de IL-10 foi reduzida (p < 0,001) apenas no grupo controle. Houve diferença significativa entre os grupos em relação às alterações de HbA1c, colesterol total e lipoproteína de baixa densidade. Não houve alterações (p > 0,05) na capacidade antioxidante total e F2-isoprostano. Este estudo desenvolveu uma bebida funcional com boa qualidade em termos de sobrevivência de bactérias e características sensoriais e nutricionais. A ingestão regular da bebida contendo probióticos melhorou o controle glicêmico em diabéticos, no entanto, a ingestão de leite fermentado caprino saborizado com suco de uva, esteve envolvido com outras alterações metabólicas.
The administration of probiotics and prebiotics has been reported to be one of the most widely used approaches to modulate intestinal microbiota. Interestingly, type 2 diabetes has been associated with dysbiosis and one of the possible routes for restore a healthy gut microbiota is by the regular ingestion of probiotics, which has been highlighted in the food industry. The present study aimed, first, to develop a flavored fermented goat milk containing probiotics and assess their metabolic effect in diabetics. Fermented milk with or without probiotic bacteria (Lactobacillus acidophilus La-5 and Bifidobacterium animalis subsp. lactis BB-12) were subjected to physicochemical, microbiological and sensory analysis, besides the nutritional characterization of the product, including antioxidant activity. Total phenolic contents and antioxidant activity of probiotic flavored fermented milk were significantly higher (p < 0.01) than conventional fermented milk. A higher loss in cell viability was observed for L. acidophilus than for the B. animalis. However, the viability of all bacteria was adequate (> 106 cfu/mL) until day 28 of storage. The fermented milk showed good sensory characteristics and no significant sensory preference among the fermented milks was found. A double-blind, randomized, placebo-controlled study including 50 diabetic patients, was developed later. The subjects were divided into two groups, receiving 120 mL/ day one of the fermented milks for 6 weeks. Anthropometric measurements, body composition, fasting blood and faecal samples were taken at baseline and after 6 weeks of intervention. The study demonstrated a significant decrease in fructosamine levels (p ≤ 0.05) and haemoglobin A1c tended to be lower (p = 0.07) in probiotic group. TNF- α and resistin were significantly reduced and faecal acetic acid was increased in both groups after the end of trial, while IL-10 was reduced (p < 0.001) only in the control group. There was a significant difference between groups concerning mean changes of HbA1c, total cholesterol and low-density lipoprotein. No significant changes (p > 0.05) from baseline were detected in plasma total antioxidant status and F2-isoprostane. This study developed a beverage of good quality, in terms of survival of bacteria and sensory and nutritional characteristics. Probiotic flavored fermented milk consumption improved the glycemic control in diabetic subjetcs, however, the intake of flavored fermented goat milk was involved with others metabolic changes.

Fluorescent light exposure has well documented negative effects on fluid milk through oxidation reactions. A shift to light-emitting diode (LED) lights in retail dairy cases has occurred due to increased energy efficiency, but the effects of LED light on fluid milk are not known. The objective was to study the interaction of light protective additives (LPA) with a high oxygen barrier package under fluorescent and LED lighting conditions simulating a retail refrigerated dairy case. The extent of oxidation in 2% milk packaged in polyethylene terephthalate (PET) packages with different light interference properties (UV barrier, 2.1% titanium dioxide (TiO2) LPA, 4.0% TiO2 LPA, 6.6% TiO2 LPA) under light exposure up to 72h was compared to control packages (light-exposed, light-protected). Chemical measures of oxidation included dissolved oxygen content, formation of secondary lipid oxidation products, riboflavin degradation, and volatile analysis by electronic nose. Changes in dissolved oxygen content were associated closely with oxidation changes in milk over 72h. PET with 6.6% TiO2 was the most successful package, based on triangle test methodology, protecting milk sensory quality similar to light-protected milk through 8h LED light exposure. Based on a 9-point hedonic scale, (1=dislike extremely, 9=like extremely), consumers liked milk stored under LED light more (α=0.05; 6.59 ± 1.60) than milk stored under fluorescent light (5.87 ± 1.93). LED light is less detrimental to milk quality than fluorescent light and PET with high levels of TiO2 can protect milk quality for short periods of time under typical retail storage conditions.
Master of Science in Life Sciences

Milk is often packaged in translucent containers providing little protection against flavor degradation from light. The effectiveness of TiO2 modifications of high density polyethylene (HDPE) packaging in affecting light-induced oxidation of extended shelf-life milk (2% total fat) and omega-3 fatty acid enriched milk (2% total fat) was studied. Packaging effectiveness was determined by assessing product quality, including changes in flavor, measuring changes in volatile compounds, thiobarbituric reactive substances and riboflavin concentrations.  Products were evaluated over a 35-day shelf-life when stored under fluorescent light (2200 lux) at 4"C. HDPE packaging included clear (no TiO2) serving as control (light exposed: no light barrier, light protected (foil overwrap) and three different TiO2 levels (low, medium, high) for the experimental treatments (total of five packaging treatments). TBARS was a good predictor of the perception of changes in sensory characteristics in 2% milk.. Under the experimental conditions used, a TBARS value of 1.3 mg/L could be considered the limiting sensory threshold for oxidized milk. Riboflavin concentration decreased by 10.5% in the light-protected control over 36 days and 28.5% in the high TiO2 packaged 2% milk, but losses were greater than 40% for all other packages. In omega-3 enriched milk, the high TiO2-HDPE package provided greater protection of sensory quality and riboflavin than clear, low and medium TiO2 packaging. However riboflavin decreased by 28% even in the light protected control which is a higher loss than observed in 2% fluid milk without omega-3 lipids. TBARS was greater than 4 mg/L in all products, including the light-protected control within three days, suggesting that oxidative stability was low. Omega-3 milk packaged in clear HDPE package exceeded MDA of 3 mg/L by day 7, suggesting the milk would have changes in sensory quality related to oxidation. The high TiO2 package protected riboflavin concentration from degradation and controlled MDA concentration the best of the TiO2 treatments through the test period in both fish oil enriched and non-enriched products.
Master of Science in Life Sciences

Thesis presented in partial fulfilment of the requirements for the degree of Master of Technology (Food Technology) Department of Food Technology Faculty of Applied Sciences Cape Peninsula University of Technology, 2012
The aim of this study was to evaluate bambara groundnut milk (BGNM) subjected to fermentation with lactic acid bacteria (LAB) as a probiotic beverage with a view to developing value-added product. Central Composite Rotatable Design (CCRD) was used to optimise the hydration time and temperature of BGN flour for optimum BGN milk (BGNM) production. The optimum time and temperature was 2 h at 25oC. The effect of variety was assessed on the quality and consumer acceptability of BGNM prepared from five varieties of BGN (black, red, brown, brown-eye, and black-eye) which were representatives of the BGN available in South Africa. BGNM from the five varieties differed significantly (p<0.05) in, lightness, chroma, redness, yellowness, hue and antioxidative activity, while the pH were not significantly different. The four BGNM samples were significantly different (p < 0.05) in appearance, colour, mouthfeel and overall acceptability but not in aroma and taste. A three factor design (4 x 3 x 3) consisting of probiotics (Lactobacillus acidophilus, L. bulgaricus, L. casei and L. plantarum), temperature and fermentation time, were used to estimate the optimal conditions for the production of BGN probiotic beverage (BGNPB). The optimal condition for the production of BGNPB was estimated to be 35oC for 24 h with a desirability of 0.854 for L. bulgaricus. The next promising probiotic was L. plantarum that could be fermented at 35oC for 24 h with 0.843 desirability. BGNM from the red variety were fermented with L. bulgaricus and L. plantarum and L bulgaricus (in combination), making plain and sweetened BGNPB which were evaluated for their quality and consumer acceptability. The four BGNPB samples were significantly different (p < 0.05) in aroma, taste, mouthfeel and overall acceptability but not in appearance and colour. The plain BGNPB were assessed for their proximate composition, antioxidant activity, in vitro probiotic tolerance to simulated gastric juices and bile and a 28 days shelf life study at 5, 15 and 25oC. The protein, total dietary fibre (TDF), ash and antioxidative activity of the BGNPB were significantly different while the fat and carbohydrates were not significantly different. Time and concentration of the gastric juice and bile had significant effects on the percentage bacterial survival of probiotics in the BGNPB. However, the probiotics did survive, in low numbers, in the simulated gastric juice and bile after 180 and 240 minutes of incubation. Titratable acidity, pH, microbial load and colour of the BGNPB were significantly affected by the storage time and temperature during the shelf life study. At the 5oC storage temperature the BGNPB had a right censored shelf life on day 28. At 15oC the shelf life was 18 and 10 days for L bulgaricus and L. plantarum and L. bulgaricus respectively. The outcome of this research showed that a novel BGNPB product can be made from fermenting BGNM with LAB.

Orientador: Walkiria Hanada Viotto
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: O iogurte e um produto necessariamente estocado e transportado sob refrigeração e por um tempo limitado. Uma alternativa para prolongar sua vida-de-prateleira consiste na aplicacao de um tratamento termico apos a fermentacao. O objetivo do trabalho foi avaliar o impacto da intensidade do tratamento termico pos-fermentacao (75°C/15s x 110°C/4s) e da temperatura (25-30°C x 5-7°C) e tempo de estocagem (21 semanas) na qualidade e vida-util de ¿leite fermentado tratado termicamente¿ estabilizado por pectina. Leite desnatado contendo 12% de acucar foi tratado a 80°C/30min, e adicionado de cultura lactica (Streptococcus thermophillus e Lactobacillus bulgaricus Yo-Mixê 601 Lyo, Danisco Brasil) a 42-45°C ate se atingir pH 4,6. Pectina (0,45% de Grindstedê Pectin AMD 382, Danisco Brasil) foi adicionada com acucar (2%), corante Carmim e aromatizante sabor morango. O iogurte foi tratado em trocador de calor tubular com homogeneização asseptica (15MPa e 5MPa) e envasado em fluxo laminar, em garrafas de PEAD de 500mL, com selo de aluminio, previamente irradiadas a 5kGy. A qualidade e estabilidade do iogurte foi avaliada a cada 3 semanas, atraves de analises microbiologicas (contagem total, bacterias lacticas e bolores e leveduras), fisico-quimicas (pH e acidez titulavel, sedimentacao e sinerese, viscosidade aparente, tamanho de particulas e cor), e sensoriais (testes de aceitacao, com avaliacao de aparencia, sabor, viscosidade e impressao global e testes de intencao de compra, por 30 provadores nao treinados). O fim da vida-deprateleira foi determinado quando um dos atributos sensoriais atingiu media 5,0. Foi utilizado um delineamento do tipo split-split-plot com 2 blocos, resultando em 4 amostras para cada bloco. A intensidade do tratamento termico influenciou a contagem total e de bacterias lacticas, sendo que, com o tratamento mais brando, o produto apresentou entre 100-200 UFC/ml e, com o tratamento mais intenso a contagem foi <1 UFC/ml. A temperatura de estocagem nao influenciou a estabilidade microbiologica dos produtos, que mantiveram as contagens iniciais durante as 21 semanas de analise. Nao houve crescimento de bolores e leveduras. A estabilidade fisica do produto nao foi afetada pela intensidade do tratamento termico e condicoes de estocagem. O unico parametro afetado foi a viscosidade, que foi menor a temperatura ambiente (35cp x 25cp). Nao houve mudancas no pH (~4,0), acidez titulavel (~1,1% de acido lactico), sedimentacao (2-3%), sinerese (inexistente) e tamanho de particulas (£3,5mm) devido a intensidade do tratamento termico, temperatura de estocagem e tempo de armazenamento. As 3 variaveis influenciaram na avaliacao do sabor e, consequentemente, na impressao global e intencao de compra. Os iogurtes tratados menos intensamente (72°C/15seg) receberam notas superiores durante toda a avaliacao. Nos produtos refrigerados, as medias de avaliacao de sabor aumentaram apos a terceira semana (de 6,2 a 7,1), devido ao desaparecimento de um sabor residual formado no tratamento termico. A temperatura de estocagem influenciou na determinacao da vida-de-prateleira. Em temperatura ambiente, a vida-util do iogurte de tratamento mais brando (72°C/15seg) foi de 15 semanas, e o de tratamento mais intenso (110°C/4seg), 9 semanas. Apos 5 meses, os iogurtes mantidos sob refrigeracao apresentavam medias superiores a 6,5, bastante distantes do final da vida-util
Abstract: Traditional yoghurt has a limited shelf-life and its storage and distribution requires refrigeration. Heat treatment after fermentation may be an alternative method to extend its shelf-life. The purpose of this study was to investigate the impact of post-fermentation heat treatment intensity (75°C/15s x 110°C/4s) and storage temperature (25-30°C x 5- 7°C) and time (21 weeks) on the quality and shelf-life of ¿heat treated fermented milk¿, stabilized by pectin. Skim milk with 12% sugar was heated at 80°C/30min and 2% EPS producing starter culture (mix of Streptococcus thermophillus and Lactobacillus bulgaricus: Yo-Mixê 601 Lyo from Danisco Brasil) was added at 42-45°C, until reaching pH 4.6. Pectin (0,45% of Grindstedê Pectin AMD 382, from Danisco Brasil) was added with sugar (2%), Carmim colorant and strawberry flavouring. The yoghurt was treated in a tubular heatexchanger followed by asseptic homogenization (15MPa e 5MPa), and bottled in a laminar flow, in 500mL PEAD bottles with aluminium seal, previously treated with 5kGy of gamma irradiation. The quality and stability of the fermented milks were evaluated every 3 weeks, by microbiological analyses (standard plate count, lactic acid bacteria and yeasts and moulds); physico-chemical analyses (pH and titratable acidity, sedimentation and syneresis, apparent viscosity, particle size, and color); and acceptability and buying intention tests. The end of shelf-life was determined by reaching mean value 5,0 for any sensory attribute. A split-split-plot design was applied and the results were evaluated by ANOVA. Heat treatment intensity influenced standard plate counts and lactic acid bacteria, whereas the less intensely treated products counts resulted in 100-200 UFC/mL, against <1 UFC/ml for the more intensely treated products. Storage temperature did not affect microbiological stability of the fermented milks, which maintained the same counts during the 21 weeks. No growth of moulds and yeasts was detected during the whole period, in all samples, independently of the storage temperature. Heat treatment intensity and storage condition didn¿t affect the physical stability of the samples, since no physical changes occurred during all the storage time. The only parameter affected was the viscosity, which was lower in ambient condition (25cp x 35cp). There were no changes in pH (4.0), acidity (1.1% lactic acid), sedimentation (2-3%), syneresis (none) and particle size (£3.5mm) due to the heat treatment intensity and storage temperature and time. The 3 variables influenced the flavor evaluation and, consequently, global impression and buying intention. Fermented milks treated less intensely (72°C/15s) had higher mean values during the whole period of evaluation. Mean values for flavor increased after the 3rd week of refrigerated storage (6.2 to 7.1), due to disappearance of an off-flavor originated from heat treatment. Storage temperature influenced the shelf-life determination. At ambient temperature, shelf-life was 3 months and a half for fermented milk treated at 72°C/15s; fermented milks treated at 110oC/4s had a shelf-life of 2 months. After 5 months, fermented milks kept under refrigeration showed sensory mean values higher than 6.5, far away from the end of shelf-life
Mestrado
Mestre em Tecnologia de Alimentos

1-4% of pulse fractions including pea protein and fiber, chickpea and lentil flour as well as soy flour and protein concentrate were selected and characterized. As preliminary results the functional properties of pulse ingredients are varied upon their protein content and pH of the food carrier. Orange juice, apple juice, yogurt and two probiotic fermented milk were selected for supplementation. 1% and 2% pulse fractions gave comparable results in terms of turbidity, cloud and visual stability, color and sensory attributes for both orange and apple juices beverages. All supplements improved the acidification rate of yogurt and probiotic cultures, but the highest effects were obtained with probiotic supplementation with lentil and soy flour. As for the main study, skim milk (9.5 % w/v solid content) was supplemented with 1-3% (w/v) lentil flour, pea flour or skim milk powder and they were inoculated with yogurt starter cultures or probiotic (L. rhamnosus). Acid production during the fermentation, the pH, syneresis, color, rheological properties (dynamic oscillation temperature sweep test at 4-50 ˚C), and sensory properties (only for yogurt) were studied after production and 28 days of refrigerated storage.1-3% lentil and pea flour enhanced acid production during yogurt fermentation, but the microbial population (CFU) of both S. thermophilus and L. bulgaricus were in the same range in all lentil and pea flour and skim milk supplemented yogurts, after production. Pea flour supplementation enhanced survival of L. bulgaricus after storage. The pH decreased from 4.5 to 4.1 in lentil flour and from 4.5 to 3.75 in pea flour supplemented yogurts, after 28 days. Syneresis in 1-2% lentil and pea flour supplemented yogurts was higher than other samples. In lentil supplemented yogurts, "a" and "L" values did not significantly differ in all samples and remained constant after 28 days whereas, "b" value increased as a result of supplementation. Pea flour supplementation did not alter redness or greenness of yogurts, but the yellowness was significantly higher than other yogurts. Yogurt with 3% lentil and pea flour had higher storage (G΄) and loss (G˝) moduli in comparison with samples supplemented with 1-3% skim milk and the control yogurt. 1-2% lentil and pea flour supplemented yogurt showed comparable sensory properties in comparison with 1-2% skim milk supplemented and control samples.1-3% lentil and pea flour enhanced acid production during probiotic fermentation, and the CFU's of L. rhamnosus were comparable with non-supplemented control sample after production. After 28 days, the CFU`s of 2% and 3% lentil supplemented probiotic were as high as 1% skim milk supplemented sample and the CFU`s of 3% pea flour supplemented probiotic was the highest followed by 3-2% skim milk and 1-2% pea flour supplemented samples. The pH decreased from 4.50 to 3.90 for lentil flour supplemented probiotics and from 4.50 to 4.04 for pea flour supplemented probiotics, over 28 days. Syneresis in 1-3% lentil and pea flour supplemented probiotic was significantly lower than other samples. All lentil flour supplemented samples had significantly lower "L" values and higher "b" and "a" values in comparison with skim milk supplemented samples. Pea flour supplementation slightly changed the color which was not as light as skim milk supplemented samples and they showed more yellowness in final product after production and storage. Probiotic fermented milk with 1-3% lentil and pea flour showed higher G΄ and G˝ in comparison with other samples.
Des légumineuses tels que des protéines et fibres de pois, farine de pois chiche, de lentille et de soja ont été sélectionnées et caractérisés. Des résultats préliminaires ont montré que des propriétés fonctionnelles ont variés en fonction de la teneur en protéines et du pH des légumineuses employées. Du jus d'orange et de pomme, du yogourt et deux laits fermentés à l'aide de probiotiques ont été supplémentés avec les différentes légumineuses à des taux de 1 à 4%. Les supplémentations à 1 et 2% ont donné des résultats comparables en termes de turbidité, de stabilité, de couleur et d'attributs sensoriels pour les jus d'orange et de pomme. L'addition de légumineuse a permis d'avoir une acidification plus rapide dans les yaourts et les cultures probiotiques, mais le effet le plus important a été obtenu avec farine de lentilles et le soja dans les cultures probiotiques. Comme précédemment, des laits écrémés (9,5% p/v) ont été supplémentés avec 1-3% (p/v) de farine de lentilles, de pois ou de poudre de lait écrémé. Ils ont été inoculés avec des cultures de yogourt, des probiotiques (L.rhamnosus). La production d'acide lors de la fermentation, le pH, la synérèse, la couleur, les propriétés rhéologiques (essai dynamique balayer oscillation de température à 40-50˚C), et les propriétés sensorielles (uniquement pour les yogourts) ont été étudiés après la production et durant 28 jours d'entreposage frigorifique. 1-3% de farine de lentilles ou de pois ont amélioré la production d'acide pendant la fermentation du yogourt, mais les UFC ont les même compte pour les laits suppléments que pour les témoins (lait écrémé). Il est a noter que L. bulgaricus avaient un meilleur taux de survie au jour 28 avec une supplémentation en farine de pois. La diminution du pH dans les yogourts est de 4,5 à 4,1 avec la farine de lentille et de 4,5 à 3,75 avec farine de pois, après 28 jours. La synérèse pour les yogourts supplémentés à 1 et 2% avec de la farine de lentille ou de pois était supérieure d'autres échantillons. Lorsque le taux de supplémentation augmente en farine de lentille ou de pois, il n'y a pas de différence significative pour les valeurs de a alors que la valeur b a augmenté en fonction de la supplémentation.Les yogourts faits de 1 a 3 % farine de lentilles et de pois 1 3% avaient un module élastique (G') et un module visqueux (G˝) plus élevés que les échantillons supplémentés en lait écrémé et que les témoins. Les Yogourts avec 1 à 2% de farine de lentilles et de pois possèdent des propriétés sensorielles comparable a celles des yogourts faits avec 1 a 2% de lait écrémé et celles des témoins. 1-3% de farine de lentilles ou de pois dans des laits avec probiotiques ont amélioré la production d'acide pendant la fermentation, et les UFC de L rhamnosus étaient comparable a ceux des témoins (lait écrémé) après production. Après 28 jours, les UFC pour les échantillons supplémentés avec 2 et 3% de farine de lentille étaient aussi élevées que ceux supplémentés avec 1% de lait écrème et les UFC pour les échantillons supplémentés avec 3% de farine de pois étaient plus élevées que ceux de tous les autres échantillons. Durant les 28 jours de production le pH diminue dans les laits probiotiques contenant de la farine de lentille de 4,50 à 3,90 et pour ceux contenant de la farine de pois de 4,50 à 4,04. La synérèse dans laits probiotiques avec 1 à 3% de farine de lentilles ou de pois a été significativement plus faible que les autres échantillons. Tous les échantillons contenant de farine de lentilles avaient significativement une valeur de L plus bas et des valeurs de b et a plus élevés en comparaison aux échantillons supplémentés en lait écrémé. L'addition de farine de pois a entraîné une modification de couleur b.Les laits probiotiques supplémentés avec 1 a 3 % de farine de lentilles et de pois ont des valeurs de G' et G˝ supérieures aux autres échantillons.

An increased interest in functional beverages is occurring, and omega-3 fatty acids (FA) are one of the most commonly sought ingredients to fortify such beverages. Omega-3 FA produce beneficial health effects, likely due to their anti-inflammatory properties. The majority of current omega-3 FA-fortified products include marine-derived omega-3 FA sources, often producing undesired flavors due to lipid oxidation. Little research regarding incorporation of alpha-linolenic acid in functional beverage formulation has been conducted. Alpha-linolenic acid is less susceptible to oxidation and may be a candidate to deliver omega-3 FA into the diet via functional products. Flaxseed is the richest plant source for alpha-linolenic acid; consumption may increase omega-3 FA intake and lower the omega-6:omega3 FA ratio, thereby, attenuating inflammation. Finely ground flaxseed was, therefore, incorporated into a chocolate milk foundation ("flaxmilk") to increase dietary omega-3 FA. An untrained consumer panel tasted and rated flaxmilk's palatability using a 9-point hedonic scale. A score of "6.0" ("like slightly") was targeted. A mean hedonic score of 6.35 was achieved, surpassing the targeted score and indicating an acceptable product. Sensory and analytical analyses of flaxmilk were conducted and compared to standard chocolate milk. Flaxmilk was significantly different in most physical, chemical and sensory characteristics compared to chocolate milk. A reduction in the omega-6:omega-3 FA ratio may attenuate inflammation; inflammation has been linked to osteoporosis. Thus, a secondary analysis of data collected from 202 women was conducted to estimate the dietary omega-6:omega-3 FA ratio and examine relationships between the omega-6:omega-3 FA ratio and total body and site-specific bone mineral density (BMD). The omega-6:omega-3 FA ratio had no appreciable association with any measure of BMD in the overall sample of women or in younger or older subsamples of women. In summary, consumers found flaxmilk to be an acceptable product, despite sensory and compositional differences compared to chocolate milk. The relationship between the omega-6:omega-3 FA ratio and BMD remains unclear.
Ph. D.

Orientadores: Maria Aparecida Azevedo Pereira da Silva, Maria Regina Bueno Franco
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Os salames são produtos cárneos fermentados e desidratados/maturados apreciados mundialmente e possuem características sensoriais peculiares, principalmente envolvendo o aroma e sabor. No Brasil este produto tem conquistado sucessivos recordes em faturamento no mercado interno, registrando R$ 265,3 milhões em vendas no ano 2005. Apesar de sua importância econômica, poucos estudos envolveram o perfil de voláteis do produto brasileiro e, nenhum deles avaliou a importância odorífera dos compostos voláteis. Assim, os objetivos do presente estudo foram: otimizar as condições de isolamento dos voláteis de salame para duas técnicas diferentes, headspace dinâmico (HD) e microextração em fase sólida (SPME); a partir destes métodos, caracterizar quantitativamente (CG-DIC) e identificar (CG-EM) os voláteis das amostras de salame brasileiro; determinar o impacto odorífero dos compostos voláteis (CV) presentes na amostra mais aceita pelos consumidores, por duas técnicas de CGO, OSME e Freqüência de detecção dos odores; determinar através da ADQ, o Perfil Sensorial dos salames e verificar a aceitação destes por consumidores potenciais; e por fim, correlacionar as medidas instrumentais com as sensoriais por métodos estatísticos multivariados. Foram analisadas seis amostras de salames brasileiros de dois tipos -Italiano (SI-1, 2 e 3) e Milano (SM-1, 2 e 3)- produzidos por três grandes fabricantes. As condições ótimas de isolamento obtidas com o auxílio da metodologia de superfície de resposta para o método de HD corresponderam à 3h e 26¿ de captura a 40°C, enquanto que para o de SPME, foram 45 minutos de extração a 50°C. A representatividade do aroma original da amostra de salame obtido nas condições otimizadas por SPME (7,2) foi superior à alcançada pelo método de HD (6,4). No entanto, ambos os métodos foram eficientes para discriminar as amostras de salame através da composição de voláteis, apesar dos diferentes perfis cromatográficos. Nos dois casos, os resultados da Análise de Componentes Principais (ACP) revelaram que as amostras dos fabricantes 1 e 2 foram caracterizadas por compostos provindos principalmente da oxidação de lipídeos, da atividade proteolítica e da fermentação de carboidratos (aldeídos, ésteres, álcoois e cetonas alifáticas), enquanto que as amostras do fabricante 3 apresentaram áreas maiores dos compostos com o grupo funcional fenol e de algumas cetonas cíclicas. Adicionalmente, os salames SI-2, SM-2 e SI-3 distinguiram-se das amostras SI-1, SM-1 e SM-3, pela maior quantidade de terpenos, o que sugere um maior grau de condimentação para aquelas amostras. As análises realizadas por CG-O (OSME e Freqüência de detecção dos odores) revelaram elevada correspondência quando aplicada a um mesmo método de isolamento. Além disso, apesar das diferenças entre os métodos de isolamento empregados, foram comumente importantes para o aroma de salame tipo Italiano os compostos metilalilsulfeto, os ésteres acetato de metilpropila, butanoato de etila, 2- e 3-metilbutanoato de etila, 1-octen-3-ona, 2-ciclohexen-1-ona, 1-octen-3-ol, 2-nonanona, (E)2-octenal, linalool, ácido 3-metilbutanóico, p-guaiacol, p-creosol e 1,4-dimetoxi-2-metilbenzeno. No teste de aceitação, realizado com 96 consumidores, a amostra SM-1 apresentou maior escore de aceitação global, e juntamente com as amostras SI-1 e SI-2 formaram um segmento com a maior parte dos consumidores ajustados no Mapa Interno de Preferência. Os resultados da ADQ foram analisados em dois grupos de atributos: aparência/textura e aroma/sabor das amostras. No primeiro grupo, os atributos distribuição da gordura e tamanho dos glóbulos de gordura discriminaram as amostras em função dos tipos dos salames e a cor vermelha diferenciou os fabricantes. Já os atributos de aroma e sabor foram correlacionados com 51 compostos voláteis (SPME), selecionados pelo seu elevado poder de discriminação das amostras e importância odorífera, juntamente com as propriedades físico-químicas, por PLSR-2. Assim, as amostras do fabricante 3 foram caracterizadas por aroma e sabor de defumado, as quais mostraram elevada correlação com os compostos fenólicos e cetonas cíclicas. O salame SM-2 apresentou maior proporção de compostos provenientes da oxidação lipídica e foi fortemente correlacionado com os atributos aroma e sabor de ranço. Já as amostras SI-2 e SM-1 foram descritas com aromas ácido e de gordura e sabor de gordura, e foram correlacionadas com teores elevados de gordura e por CVs originados da oxidação de lipídeos e da degradação de proteínas e carboidratos. A amostra SI-1 apresentou elevada quantidade de ácido acético, metionol e dos compostos recentemente relatados e, ainda foi caracterizada pelo maior teor protéico. Com as mesmas variáveis, os modelos desenvolvidos para prever os escores dos atributos sensoriais mostraram ajustes adequados (r>0,9) e habilidade de previsão (erro padrão médio de 15,3%). Desta forma, este estudo proporcionou informações sobre a qualidade dos salames brasileiros, incluindo os perfis dos constituintes voláteis e sensoriais das amostras, além de determinar a importância odorífera dos voláteis da amostra mais aceita com relação ao aroma
Abstract: Dry-fermented sausages are meaty products resulting from fermentation and dehydration/ripening processes. They are produced and consumed worldwide because of their typical sensory characteristics mainly in relation to the aroma and flavor. In Brazil this product has reached successive record sales in the internal market, with a total sale of R$ 265 million during the year 2005. In spite of its increased commercialization in the country, few studies about the volatile compounds of Brazilian dried sausages were found and their odoriferous importance had not been evaluated. The aims of the present study were: to optimize the conditions for the isolation of the salami volatile compounds by two different techniques, dynamic headspace (HD) and solid phase microextraction (SPME); to characterize the volatile compounds of some Brazilian salami samples by a gas-chromatograph equipped with a flame ionization detector (GC-FID) and by massspectrometry (MS), using the optimized techniques of isolation; to determine the odoriferous impact of the volatile compounds of the most accepted sample by two olfactometric techniques, OSME and Frequency of odor detection; to determine the sensory profile of the samples by Quantitative Descriptive Analysis (QDA), verifying also their acceptability by potential consumers; and finally to correlate the instrumental and sensory data using multivariate statistic techniques. Six different Brazilian dried sausage samples of the Italian (SI-1,2,3) and Milan types (SM-1,2,3) from three important national producers were analyzed. The optimized conditions for the isolation of the volatile compounds determined with the aid of Response Surface Methodology were 3h 26¿ (trapping time) and 40°C (temperature trapping) for the HD technique and 45¿ (extraction time) and 50°C (extraction temperature) for the SPME. Evaluation of the original aroma of the sample extracted by SPME obtained a higher score (7.2) than that of the HD technique (6.4). However, both methods were efficient in discriminating the salami samples by comparison of the volatile compounds in spite of their different chromatographic profiles. The data obtained from the two methods interpreted by Principal Component Analysis revealed that the samples from producers 1 and 2 were characterized mainly by compounds arising from lipid oxidation, proteolytic activity and carbohydrates fermentation (aldehydes, esters, alcohols and aliphatic ketones). The samples from producer 3 were characterized by greater areas of phenolic compounds and by cyclic ketones. Additionally, the samples SI-2, SM-2 and SI-3 could be distinguished from the SI-1, SM-1 and SM-3 by a higher amount of terpenes, suggesting that more condiments were added to these samples. On the other hand, the analyses carried out by GC-O (OSME and Frequency) showed good agreement when applied to volatile compounds isolated by the same procedure. In spite of the different chromatographic profile obtained by the two methods, the compounds methylallylsulfide, methylpropyl acetate, ethyl butanoate, ethyl 2- and 3-methylbutanoate, 1-octen-3-one, 2-cyclohexen-1-one, 1-octen-3-ol, 2-nonanone, (E)2-octenal, linalool, 3-methylbutanoic acid, p-guaiacol, p-creosol and 1-4 dimethoxybenzene were considered important for the Italian type salami aroma by both olfactometry techniques. An acceptability test applied to 96 potential consumers showed that the SM-1 sample obtained the highest score of overall acceptability and together with the SI-1 and SI-2 samples, they formed a segment with the major part of the consumers adjusted in the Internal Preference Mapping. The QDA data were interpreted after division of the samples¿ attributes in two groups: appearance /texture and aroma/flavor. In the first group, the distribution of fat and size of fat globules discriminated the samples in terms of the salami types while the red color differentiated the producers. The attributes of aroma/flavor were correlated to 51 volatile compounds (SPME) which were selected because of their high discriminatory power in relation to the samples and the odoriferous importance, and to the physicchemical properties by PLSR-2. Thus, the samples of producer 3 were characterized by a smoke aroma/flavor and they showed a high correlation to phenolic compounds and cyclic ketones. The SM-2 sample, characterized by a high proportion of compounds arising from lipid oxidation, was strongly correlated to the aroma and flavor attributes of rancidity. The samples SI-2 and SM-1 were described by acidic and fatty aroma attributes and fatty flavor and they were correlated to high amounts of fat and also to the volatile compounds originating from lipid oxidation and from protein / carbohydrate degradation. The SI-1 sample showed high amounts of acetic acid, metionol, the recently reported compounds and total protein. Considering the same variables, the models developed in order to predict the scores of the sensory attributes of the samples showed adequate adjustment (r>0.9) and prediction ability (mean standard error of 15.3%). Thus, this study provided some information concerning the quality of Brazilian salami samples, including the volatile and sensory profiles, in addition to the determination of the odoriferous importance of the volatile compounds present in the most accepted salami aroma
Doutorado
Consumo e Qualidade de Alimentos
Doutor em Ciência de Alimentos

Tiger nuts (Cyperus esculentus L) are recognized as a high potential, alternative source of food nutrients. However, there is limited scientific literature on the technological possibilities for developing value-added foods, such as fermented products from tiger nut milk. Therefore, strategies for producing and improving the properties of fermented tiger nut milk were investigated for generating lactose-free, nutritious yogurt-like products with acceptable sensory properties and a prolonged shelf life quality. A wet-milling procedure was standardized for extracting tiger nut milk from tiger nuts, and the effects of the extraction process on nutrient distribution, colour properties and colloidal stability of the milk were analyzed. Next, tiger nut milk was enriched with proteins and/or hydrocolloids and the impact of the additives on the physical properties of the milk were determined. Enriched tiger nut milk was fermented by using classical yogurt cultures and the obtained products were analyzed for the microbiological, physico-chemical and sensory characteristics. Additionally, effects of enriching tiger nut milk with microbial transglutaminase cross-linked proteins on the microbiological and physico-chemical properties were evaluated. Higher wet-milling intensity improved the nutrient composition, colloidal stability and colour of the milk. Enrichment of tiger nut milk with milk proteins and xanthan gum enhanced the viscosity and stability, and after fermentation, led to homogenous gel-like products with superior microbiological, physico-chemical and different sensory properties compared to the fermented plain tiger nut milk. Microbial transglutaminase cross-linked proteins improved the physical characteristics of the fermented product, especially during storage. This product would be relevant in many developing countries with high prevalence of lactose intolerance, limited access to nutritious food but show a high distribution of tiger nut vegetation
Erdmandeln (Cyperus esculentus L) haben ein hohes Potential als alternative Quelle Lebensmittelinhaltsstoffen. Allerdings gibt es nur in begrenztem Ausmaß Literatur über technologische Möglichkeiten zur Entwicklung von Mehrwert-Lebensmitteln wie fermentierter Erdmandelmilch. Daher wurden Strategien zur Herstellung und Verbesserung der Eigenschaften von fermentierter Erdmandelmilch zur Erzeugung laktosefreier joghurtähnlicher Produkte mit akzeptablen sensorischen Eigenschaften untersucht. Für die Extraktion der Erdmandelmilch wurde ein Nassmahlverfahren standardisiert und der Einfluss des Verfahrens auf die Nährstoffverteilung, die Farbeigenschaften und die kolloidale Stabilität der Milch analysiert. Als nächstes wurde Erdmandelmilch mit Proteinen und/oder Hydrokolloiden angereichert, und der Einfluss der Additive auf die physikalischen Eigenschaften des Extrakts bestimmt. Angereicherte Erdmandelmilch wurde mit klassischen Joghurtkulturen fermentiert, und die mikrobiologischen, physikalisch-chemischen und sensorischen Eigenschaften der Produkte wurden untersucht. Zusätzlich wurden Effekte der Anreicherung von Erdmandelmilch mit enzymatisch vernetzten Proteinen auf die mikrobiologischen und physikalisch-chemischen Eigenschaften bewertet. Eine höhere Nassmahlintensität verbesserte die Nährstoffzusammensetzung, die kolloidale Stabilität und die Farbe der Milch. Die Anreicherung erhöhte die Viskosität und Stabilität und führte nach der Fermentation zu homogenen gelartigen Produkten mit verbesserten mikrobiologischen, physikalisch-chemischen und sensorischen Eigenschaften im Vergleich zur fermentierten Erdmandelmilch. Mikrobielle Transglutaminase-vernetzte Proteine verbesserten die physikalischen Eigenschaften des fermentierten Produkts, insbesondere während der Lagerung. Dieses Produkt wäre in vielen Entwicklungsländern mit hoher Prävalenz von Laktoseintoleranz und begrenztem Zugang zu nahrhaften Lebensmitteln als Alternative von Interesse

L’objectif de la thèse est de caractériser la poudre du kishk libanais, un lait fermenté traditionnel, et d’optimiser sa technologie de transformation dans une démarche d’industrialisation. Des échantillons de poudre de kishk traditionnel ont été collectés, et leurs propriétés physico-chimiques, rhéologiques, microbiologiques et sensorielles ont été étudiées, en fonction du type de lait utilisé. Il en résulte que le kishk préparé à base de lait de chèvre est plus riche en matières grasses que les autres types. La distribution granulométrique est très large, quel que soit le type de lait, avec présence simultanée de fines particules à forme irrégulière et d’agrégats de grande taille. Les particules de poudre sont revêtues d’une épaisse couche de lipides leur conférant un caractère cohésif et une grande résistance au cisaillement. Il s’avère aussi que la soupe de kishk présente un comportement rhéofluidifiant, et ses propriétés sensorielles sont fortement liées à la région de production et au type de lait. L’effet des conditions de production optimisée sur les propriétés de la poudre et de la soupe de kishk a été également étudié. Les résultats sont prometteurs et montrent que la structure de la poudre de kishk et son comportement rhéologique n’ont pas été altérés. En effet, les deux poudres de kishk présentent des propriétés rhéologiques quasi similaires, avec une faible aptitude à l’écoulement, malgré des différences au niveau de la composition chimique et la taille des particules. Au niveau rhéologique et sensoriel, la soupe de kishk issue de la production optimisée semble plus épaisse et consistante que la soupe traditionnelle, sans dépréciation notable des qualités organoleptiques du kishk
The aim of this thesis is to characterize Lebanese kishk powder, a traditional fermented milk, and to optimize its processing technology. Samples of traditional kishk powder were collected, and their physicochemical, rheological, sensory and microbiological properties were studied based on the type of milk. As a result, kishk prepared with goat milk is richer in fat than other types. The particle size distribution is very wide, regardless of the type of milk, with simultaneous presence of fine irregularly shaped particles and large aggregates. Powder particles are coated with a thick layer of fat conferring a cohesive character and a high shear strength. Kishk soup has a shear-thinning behavior, and its sensory properties are strongly related to the production region and the type of milk. The effect of optimized production conditions on the properties of kishk powder and soup was also studied. The results are promising and show that the structure and rheological behavior of kishk powder were not altered. Indeed, the two kishk powders exhibit almost similar rheological properties, with low flowability, despite slight differences in chemical composition and particle size. Finally, kishk soup resulting from the optimized production seems thicker and consistent than traditional soup, without significant loss of the organoleptic properties of kishk

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Innovation in products elaboration is a constant purpose in the food industry in order to get differential quality attributes. For this, the development of new flavors fruit yogurt may be well received by consumers of the product, especially if these present some antioxidant properties. Thus, this study aimed to evaluate some physical and chemical properties, antioxidants and sensory of yogurt manufactured from noni pulp (Morinda citrifolia L.) and acerola (Malpighia emarginata DC.) pulp. For this, the following formulations were developed: F1- natural yogurt (control); F2 - yogurt with acerola pulp (2.5%); F3 - yogurt with noni pulp (2.5%); F4 - mixed yogurt with acerola pulp (1.25%) and noni pulp (1.25%); F5 - yogurt with acerola pulp (5%); F6 - yogurt with noni pulp (5%); F7 - mixed yogurt with acerola pulp (2.5%) and noni pulp (2.5%). The physical and chemical analysis (pH, titratable acidity, milk fat and protein), phenolic content, antioxidant activity and sensory analysis (consistency, acceptance and purchase intent) were carried out in yogurt. The data were evaluated by the Scott-Knott test and Friedman with probability of 5%. All yogurts showed physical and chemical quality according to the quality standard established by brazilian legislation. There was treatment effect on physical and chemical parameters, except to pH. The yogurts manufactured with only acerola (2.5% and 5%) obtained higher antioxidant activity (51.56% and 79.83%, respectively). There was treatment effect for the sensory attributes evaluated. The formulations F1, F2 and F4 obtained higher consistency. The yogurt with 5% noni obtained lower acceptance and purchase intention. The yogurts with noni 2.5% and 2.5% acerola obtained lower rejections. The yogurt manufactured showed acceptance similar to the natural yogurt. Thus, the new yogurt formulations show great commercial potential
A inovação na elaboração de produtos é uma finalidade constante na indústria de alimentos, visando agregar atributos de qualidade diferencial. Por isso, o desenvolvimento de novos sabores de iogurtes de frutas tende a ser bem recebido pelos consumidores do produto, ainda mais se possuírem alguma propriedade antioxidante. Assim, o objetivo deste trabalho foi avaliar algumas propriedades físico-químicas, antioxidantes e sensoriais de iogurte elaborado com polpa de noni (Morinda citrifolia L.) e acerola (Malpighia emarginata DC.). Para isto, foram desenvolvidas as seguintes formulações: F1- iogurte natural (controle); F2 - iogurte com polpa de acerola (2,5%); F3 - iogurte com polpa de noni (2,5%); F4 - iogurte misto com polpa de acerola (1,25%) e noni (1,25%); F5 iogurte com polpa de acerola (5%); F6 - iogurte com polpa de noni (5%); F7 - iogurte com polpa de acerola (2,5%) e noni (2,5%). Foram realizadas análises físico-químicas (pH, acidez titulável, gordura láctea e proteínas lácteas), teor de compostos fenólicos, atividade antioxidante e análises sensoriais (consistência, aceitação e intenção de compra). Os dados foram avaliados pelo Teste de Scott-Knott e de Friedman com probabilidade de 5%. Todos os iogurtes apresentaram qualidade físico-química conforme o padrão de qualidade estabelecido pela legislação brasileira. Houve efeito de tratamento para os parâmetros físico-químicos, exceto pH. Os iogurtes formulados somente com acerola (2,5% e 5%) apresentaram maiores atividades antioxidantes (51,56% e 79,83%, respectivamente). Houve efeito de tratamento para os atributos sensoriais avaliados. As formulações F1, F2 e F4 obtiveram as maiores consistências. A formulação com 5% de noni apresentou a menor aceitação e a menor intenção de compra. As formulações com noni a 2,5% e acerola a 2,5% apresentaram menores rejeições. A aceitação dos iogurtes formulados foi semelhante ao do iogurte natural. Assim, as novas formulações apresentam grande potencialidade comercial

The thesis is focused on the effect of dry hopping on beer senzomy and sensory profile of the top-fermented beer. The goal of this work was to modify samples of the top-fermented beer by dry hopping, to analyze them by senzomy and sensory way, to optimize the method for hop essential oils analysis and to compare the results to the available literature. The problematics of the used raw materials, analyzed substances, technological and analytical methods are discussed in the theoretical part. The practical part is composed of technological preparation of the samples and their analysis. There was used a commercial product of the type of American Indian Pale Ale in this work. There was added a Cascade hop by dry hopping into the commercial product. The basic analysis of gravity and attenuation of the beer were done on the fresh beer and the two months old beer. The selected essential oils, carbonyl compounds, bitter acids, selected metal contaminant and nitrates were established in the beer and in the hop. The samples of the beer were sensory evaluated in the same two-month interval. It was determined that the dry hopping influenced the increased pH of the beer. There was established the quantity of essentials oils in the samples and it was compared to the sensorial results. These results can be used as a base for the next exploration, some part of the results are applicable in the beer industry.

The aim of this thesis was carried out using one of the methods of analysis of sensory evaluation of selected dairy products. Based on the proposed questionnaire survey carried out simultaneously on consumption and preference for selected commodities. The thesis was part of the project ECOP CZ.1.07/2.3.00/09.0081: "Comprehensive training of human resources in the dairy."

碩士
國立中正大學
化學工程研究所
90
Food manufacturing has turned into a traditional one nowadays. It’s filled with hi-technology and contests of manufacturing. Food manufacturing doesn’t try to change its manufacturing style. It’s possibly to be gotten out. Therefore, many food factories apply biotechnology on the equipments they have. The topic of this research is on dairy manufacturing. At first, we assess the manufacturing flow chart of Lactobacillus Ferment, and then use the soft ware of SuperPro Designer to count the most reasonable manufacturing flow chart. Finally, we decide the equipment investment and make the most economical effect. The design of using biotechnological to control Lactobacillus Fermented tank is not only to count the most effective operation time, it can choose suitable content and amount Fermented Tank to connect the original manufacturing equipments. It can lifted the using rate of machines, that’s to say the investors can gain the most benefit.

The processing parameters of and processing procedures for sweetened blueberry flavored carbonated milk beverages were developed in this study. Foam formation of the milk after carbonation was controlled by a precharging of the vessel headspace. A combination of heat treatment (85°C, 30 minutes) and CMC addition was conducted to minimize the acid coagulation of casein with added fruit concentrate. Both carbonated and noncarbonated, sweetened blueberry flavored milk were evaluated by a trained panel. The effect of carbonation and sweetener source on taste properties in a blueberry flavored milk beverage system were discussed. Carbonation enhanced the sensory rating of overall intensity, sweetness and blueberry flavor. There was no significant carbonation effect on perceived viscosity. The sweetener source (sucrose, HFCS, pear concentrate and aspartame) caused a significant effect on the sensory rating of viscosity, but a nonsignificant effect on that of overall intensity, sweetness and blueberry flavor. Two consumer panels evaluated the carbonated, sweetened blueberry flavored milk beverages. The percentage of panelists who liked the products was approximately 50%. The results from the distributions of responses on a "just right" scale indicated that the carbonation and sweetness level probably were optimum formulations, and the level of blueberry flavor was too low. The results also implied that sucrose and HFCS were more appropriate sweeteners in flavored carbonated milk beverages than aspartame and pear concentrate. Two obstacles for consumer potential were the rapid separation phenomenon and the unattractive color of the products.
Graduation date: 1988

Thesis (M.Tech.: Food Technology)-Dept. of Biotechnology, Durban University of Technology, 2007 xiii, 100 leaves
There are many ways for milk and dairy products to develop flavour defects. Sensory evaluation, has been the traditional approach to characterize off flavours. The need for odour sensing devices becomes greater when volatile and semi-volatile organic compounds are present in the product in parts per billion or even in the parts per trillion concentration range that cause off flavours. Today, sophisticated, sensitive instrumental tests such as electronic nose technology coupled with gas chromatography are capable of detecting, identifying and quantifying the specific chemical agents responsible for off flavours. This study focused on the use of the electronic nose as a novel technology for the detection and monitoring of milk quality by testing the effects of heat treatment at 63˚C and shelf life. Microbiological testing, sensory evaluation and gas chromatographic analysis were carried out together with aroma profiling using the electronic nose to determine milk quality.

Fermentation of the grape must into wine is one of the most important steps in winemaking. Selected yeast strains of Saccharomyces cerevisiae have been used for many years to ensure complete and even fermentations. The formation of volatile compounds also occurs during fermentation and will influence the sensory perception of the wine. The main objective of the research was to study the sensory and chemical composition of 1992 Oregon Riesling, Chardonnay and Pinot Noir wines fermented with different commercial S.cerevisiae strains. In the first study, Free-Choice Profiling was used to study the sensory profiles of all three varieties after 7 and 20 months of aging. This method was used in order to utilize a panel of expert winemakers for the tastings. The sensory data analyzed through Generalized Procrustes Analysis showed that some strains were similar while others were different in terms of aroma and flavor at 7 months of age. After 20 months of aging, differences and similarities were still present although the sensory profiles were different from the young wines. This last finding showed that differences are still present after a period of aging. In the second study, the chemical composition of all three varieties and the volatile composition of selected wines of Riesling and Chardonnay were studied. In both white varieties, statistical differences in titratable acidity, residual sugar, volatile acidity and malate content resulted from fermentation with different yeast strains. The volatile composition was qualitatively similar, but some quantitative differences, as relative concentration, were found. Whether or not those differences had a sensory impact was not investigated. Results of the present study showed the need for further studies in order to understand the role of yeast in flavor development. Relationships between sensory profiles and volatile composition could help winemakers to understand the influence of a selected strain on a particular variety and to select yeast strains to optimize wine quality.
Graduation date: 1995

碩士
東海大學
餐旅管理學系
105
The evolution of the fresh milk market has shifted gear from few monopolies to the diverse market players consisting of imported milk, domestic name brand, farmers’ private label etc., which make the fresh milk market very competitive. It gave rise to the consumer awareness on the quality of the fresh milk focusing on the desired characteristics. This study applied sensory evaluation technique on the comparison and analysis of the fresh milk from different brands in order to investigate the product positioning of fresh milk from Flying Cow Ranch. Results indicated that brand name had a significant effect on consumer preference. In addition, the results from regression analysis suggested that freshness and smoothness were the two major factors influencing consumers’ affection on fresh milk. Practical suggestion is provided to better serve the consumer proposition by recognizing the key resource, connecting the key process and constructing the profit formula. Dairy farms such as Flying Cow Ranch can seize the white space by developing the value added fresh milk products with their advantage on the competence on the knowledge on the feed, feeding environment and processing conditions to promote their products in the growing and competitive market.

碩士
國立中興大學
食品暨應用生物科技學系所
102
Recently, health conscious of national people raising up results in output value of functional food increasing. The output value is about 85,000 million NT dollars in 2014. The cereals are the largest source of functional foods materials. Soybean is a regular consumption in Taiwan and it is rich in nutrients and functional compounds. The soybean amount of input in Taiwan is 173,469 tons in a whole year. Besides, soybean is a popular food because of unique flavor. Okara is a main by-product during the processing of soybean products. The annual output of okara was over 366,019 tons in Taiwan. It is abundant in moisture, protein and dietary fiber content. Recently, probiotics and related products are popular topic. Therefore, this research study on fermentation liquid, okara and micro hydrogel beads. The results show that the best ratio of soybean milk and okara, components of fermentation liquid, is 60:1 named SM60O1. After 24 hours fermentation, the microbial counts, pH value, total phenolic compounds content, total flavonoid content, carbohydrate content and titratable acidity are 8.76 log CFU/ml, 4.15, 0.59 mg/g dw, 0.24 mg/g dw, 1.64 mg/ml and 0.41%. Particle size results of okara fiber treated by different extents of micronized processing are 416.48, 304.92, 185.51, 48.48 and 20.30 μm. Moreover, the 20-mesh group, mean particle size is 416.48μm, has the best water-holding capacity, swelling capacity and oil-holding capacity, 9.12, 16.46 and 3.51 ml/g respectively. The complex hydrogel bead is made by 7.5% pectin and 1 % arabic gum and the ratio of them is 3:2. It is the best prepared condition and named P3A2. The moisture content, swelling capacity, hardness and enthalpy analysis of this complex hydrogel bead are 96.85%, 230.13%, 4865.6 g and 98.4 J/g. The functional hydrogel bead named SM1G2, means the ratio of soybean milk and gel is 1:2, has the best strength of bonding structure. The moisture content, swelling capacity, hardness and enthalpy analysis are 99.72%, 180.36%, 3500.67 g and 33.23 J/g. Moreover, the probiotic survival rate of SM1G2 in the stimulate gastric juice, pH value are 1.2 and 2.0, are 57.29 and 95.37%. And the microbial counts of releasing test in the intestinal liquid, after stimulate gastric juice, is 7.31 log CFU/ml. In this study, the best condition is SM1G2 functional hydrogel bead. The best concentration and ratio of mixed gel are 1 % and 3:2 of arabic gum and pectin.

碩士
國立中興大學
食品暨應用生物科技學系所
106
The classification of red grape wine is often evaluated by sommelier systems in wine industries. However, there are still many uncertainties and limitations for the classification so it can be seen as a business tool. It has been a severe challenge how to quickly and correctly evaluate the quality of the wine, how to manufacture and how to judge the wine is fermented or unfermented in the food science. At present, the inspection is built on the combination of the expert evaluation, the scientific sensory evaluation and instruments and all procedures always a lot of manpower, material resources and money. Taiwan''s unique grape wine, black queen Musca, has not been imported the scientific sensory evaluation methods to establish the complete flavor profile, sensory quality and flavor map database so that the industry cannot come into contact with the world. The purpose of this study was to analyze the sensory quality of Taiwan’s commercial red grape wine with fermented or unfermented blend using scientific consumer sensory technique and electronic tongue to judge the quality of wines and to understand how Taiwanese consumers like those sensory qualities in order to provide the domestic wine industry as reference. In this study, 26 wine (17 Taiwanese and 9 foreign products) consisted of five sections. 56-62 college students aged 20 and above were enrolled to conduct the sensory evaluation in the professional food and sensory evaluation room. About15CC and 14-17OC stored in the red grape wine was provided to assessors and they were asked to rate their liking degree and sensory perception of 31 sensory attributes and 13 feeling items after drinking the sample. The experimental design of Latin Square was used to identify the order of the samples and the data was collected by the computerized evaluation using Compusense five software. The Alpha MOS, ASTREE electronic tongue was used to evaluate samples and the color of the wine was measured using a colorimeter. The result of the 9-point test showed that the consumer acceptance of only one Taiwanese wine ranges from "slightly like" to "moderately like"; this sample has strong characteristics in fresh red berries and sweetness; 3 wines (2 French and 1 Taiwanese) had a lower degree of preference, ranging from "slightly disliked" and " moderately dislike" and they have a strong taste of bitterness, astringency, burning, and Shaoxing sake. Taiwan consumers like wines have sweetness, such as: sweet, fructose soda, cold syrup, health sugar taste, and fruit-related features such as: berry fruity, strawberry jam, grape flavor, artificial fruit flavor and etc. ; consumers do not like samples have bitterness, astringency, sourness, cypress barrel flavor and plums and so on. In terms of feelings, the degree of consumer preference is negatively correlated with the feeling of mild body, fragrance, good quality, local production and comfort, etc. It is negatively correlated with foreign imports, economy, and medium or heavy body mass. The alcohol concentration of samples showed a positive correlation with discomfort and Medium or heavy boots and a negative correlation with mild bouts of liking. The results of colors in the 31 samples showed that these samples could be divided into three categories by color classification, the color of the 14 samples belonged to the red color of “deep red stone” which has with lower values of L and b; the color of the 12 samples was rose red with a higher L and b, most wines of the black queen Musca were in this category and two of the samples belonged to mauve, with higher values of a and lower values of L and b, both of which were flavored wines of Cabernet Sauvignon. The results of the electronic tongue demonstrated that seven probes have the ability to distinguish these samples and JE, JB, BB, GA, the four probes have a superior ability for discriminating power. The results found there are obvious differences in the classification between foreign wine and Taiwan wine, either fermented or unfermented wine. In addition, the electronic tongue can distinguish between fermented and unfermented wine. The RV coefficient showed that there is a low positive correlation between the sensory evaluation and the classification of the color using the color meter and the classification of the electronic tongue has nothing to do with the result of the sensory evaluation. In this study, consumers are used to conduct wine reviews to understand Taiwanese consumers'' feelings and preferences about wine characteristics and to provide a scientific and systematic basis for the marketing of wine. In addition, there are totally a distinct flavor between the wine of black queen Musca and the Merlot and Cabernet Sauvignon Blanc wine. Electronic tongue can clearly distinguish the samples between different varieties of grapes and origin caused by the differences but human sensory evaluation cannot handle them.

碩士
國立臺灣海洋大學
食品科學系
102
gamma-Aminobutyric acid (GABA) is a well-known non-protein amino acid, which is widely distributed in animals and plants. GABA has been reported to be a major inhibitory neurotransmitter in the mammalian central nervous system and show antihypertensive activity. This aims of this research are to manufacture a GABA-enriched fermented milk by lactic acid bacteria (LAB) isolated from fish intestines and to evaluate the probiotic potential property of the GABA-producing LAB. Preliminarily, lactic acid bacteria strains were isolated from healthy fish intestine from previous study. Ten lactic acid bacteria strains of 126 LAB strains were screened based on the capacity of synthesizing GABA. And ten GABA-producing strains show that none of them exhibited hemolytic activity. Moreover, five strains exhibited partial bile salt hydrolase activity, including the strain FPS 2520. FPS 2520 also showed a high percentage of adhesion to monolayer of Caco-2 cells. Strain FPS 2520 demonstrated high survival viability to gastrointestinal conditions simulating stomach and duodenum passage. Optimal conditions of strain FPS 2520 for producing GABA in whole milk were: 10% reconstituted whole milk, initial inoculum size of 5 log CFU/mL, addition of 20 mM MSG, 1% brown sugar, and 0.5% yeast extract during fermentation at 37oC for 48 hours. The results indicated FPS 2520 show a probiotic potential property and have a great application in milk fermentation for the production of G (10.67 mg/mL), and the IC50 of ACEI-inhibitory activity is 0.28 ± 0.02 mg/mL. Besides lactic acid bacteria number slightly decreased, pH value, titratable acidity and GABA concentration didn’t have significant difference compare to control at 4oC for 14 days. Using mixed strains, GABA-producing strain FPS 2520 and proteinase-positive FKR 3737 could significantly enhance the GABA production about 14.74 mg/mL.

碩士
國立宜蘭大學
生物技術與動物科學系
103
At present, a number of lactic acid bacteria fermentation or enzyme hydrolysis of goat milk, prepared ACEI activity-derived peptide. The aim of this study is application of yeast fermented goat milk by-product (GMF) containing ACEI extracts and its sensory evaluation for ice cream. First of all, we use Bacillus subtilis alkaline protease (Alcalase) to hydrolyze GMF and to evaluate its hydrolyzing efficiency and hydrolysate containing ACEI activity. Results show GMF through enzyme hydrolysis, the product hydrolyzing efficiency produced was significantly higher than that of the unhydrolyzed group (p<0.05). However, there is no significant difference for ACEI activity between the two groups. This results show GMF by enzyme hydrolysis does not reduce the ACE activity. Thereafter, GMF by ultrasonic homogenization, 10KDa ultrafiltration membrane separation of low molecular weight extract, then purify and detect the ACEI activity. Collection ACEI activity of HPLC fractions, FA, SK-4L, SQ-4L and FB. The ACE residual activity for these 4 fractions is 88%, 69%, 61% and 76%, respectively. GMF is the product of Yeast fermentation with small size molecular structure, which containing much more loosens casein proteins and better emulsification characteristics. However, it is slightly bitter. In order to know the possibility of application GMF in ice cream production, we also evaluate its sensory function. Experiments are divided into 4 groups. Cow milk addition as the control group, the other three are goat milk addition, cow or goat milk with GMF treated as the experimental groups. Measurement of total solids (TS), pH value, total acidity, specific gravity and melting rate of ice cream is collected. Results show TS, total acidity and specific gravity are no significant difference between the groups. pH value as 6.18 for GMF treated group, significantly lower than the control group of pH 6.56. Melting rate as 1.88 (g/min), and1.67 (g/min) respectively for two goat milk treated groups, is significantly higher than the control group of 1.21 (g/min). Sensory evaluation scores taken 9-point scale, control group and the other 3 experimental groups in the ice-cream appearance, flavor, texture and overall acceptance compared, all categories in all their scoring fall in 6~7 range, shows adding GMF Ice cream with no significant differences between control group. Based on the above discussion, GMF and its separated extract are confirmed with ACE inhibitory activity. In the future, there is scope for further application for more functional foods development, and will bring real benefits to human health.

Tiger nuts (Cyperus esculentus L) are recognized as a high potential, alternative source of food nutrients. However, there is limited scientific literature on the technological possibilities for developing value-added foods, such as fermented products from tiger nut milk. Therefore, strategies for producing and improving the properties of fermented tiger nut milk were investigated for generating lactose-free, nutritious yogurt-like products with acceptable sensory properties and a prolonged shelf life quality. A wet-milling procedure was standardized for extracting tiger nut milk from tiger nuts, and the effects of the extraction process on nutrient distribution, colour properties and colloidal stability of the milk were analyzed. Next, tiger nut milk was enriched with proteins and/or hydrocolloids and the impact of the additives on the physical properties of the milk were determined. Enriched tiger nut milk was fermented by using classical yogurt cultures and the obtained products were analyzed for the microbiological, physico-chemical and sensory characteristics. Additionally, effects of enriching tiger nut milk with microbial transglutaminase cross-linked proteins on the microbiological and physico-chemical properties were evaluated. Higher wet-milling intensity improved the nutrient composition, colloidal stability and colour of the milk. Enrichment of tiger nut milk with milk proteins and xanthan gum enhanced the viscosity and stability, and after fermentation, led to homogenous gel-like products with superior microbiological, physico-chemical and different sensory properties compared to the fermented plain tiger nut milk. Microbial transglutaminase cross-linked proteins improved the physical characteristics of the fermented product, especially during storage. This product would be relevant in many developing countries with high prevalence of lactose intolerance, limited access to nutritious food but show a high distribution of tiger nut vegetation.:1. Introduction and aim 1 2. Literature review 4 2.1 Tiger nut, origin, nutritional value and food use 4 2.2 Tiger nut milk, preparation and nutrient composition 7 2.3 Colloidal characteristics of tiger nut milk 9 2.4 Factors accounting for the dispersion stability of tiger nut milk 10 2.5 Enhancing tiger nut milk stability 12 2.6 Properties of fermented tiger nut milk 17 2.7 Microbial transglutaminase and properties of fermented tiger nut milk 18 3. Methodology 21 3.1 Extraction and characterisation of tiger nut milk 21 3.1.1 Sample collection and preparation 21 3.1.2 Tiger nut milk extraction 21 3.1.3 Nutrient analysis of tiger nuts 22 3.1.4 Analysis of tiger nut products 23 3.1.5 Particle size distribution 24 3.1.6 Colloidal stability 25 3.1.7 Colour measurement 25 3.2 Stabilisation of tiger nut milk dispersion 26 3.2.1 Tiger nut milk preparation 26 3.2.2 Preparation of tiger nut milk enrichments 26 3.2.3 Gravitational stability of enriched tiger nut milk 27 3.2.4 Accelerated gravitational stability of enriched tiger nut milk 28 3.2.5 Viscosity of TNM mixtures 29 3.3 Extraction and characterisation of globular tiger nut proteins 29 3.3.1 Protein extraction and fractionation 29 3.3.2 Molecular mass of globular tiger nut proteins 31 3.3.3 Denaturation temperature of globular tiger nut proteins 32 3.3.4 Isoelectric point of globular tiger nut protein 33 3.4 Properties of fermented tiger nut milk enriched with proteins 34 3.4.1 Materials and Reagents 34 3.4.2 Preparation of plain and enriched tiger nut milk 34 3.4.3 Fermentation of plain and enriched tiger nut milk 35 3.4.4 Viable counts of starter cultures in fermented tiger nut milk systems 36 3.4.5 Chemical analysis of unfermented and fermented tiger nut milk 36 3.4.6 Physical analysis of fermented tiger nut milk products 37 3.4.7 Sensory analysis of fermented tiger nut milk products 38 3.5 Microbial transglutaminase and fermented tiger nut milk property 38 3.5.1 Preparation of plain and enriched tiger nut milk 38 3.5.2 Fermentation of plain and enriched tiger nut milk 39 3.5.3 Analysis of the enzymatically cross-linked proteins 39 3.5.4 Viable counts 40 3.5.5 pH and titratable acidity 40 3.5.6 Syneresis and viscosity 41 3.5.7 Colour of fermented tiger nut products 41 3.6 Statistical analysis 41 4. Results and discussion 43 4.1 Extraction and characteristics of tiger nut milk 43 4.1.1 Material recovery, mass transfer and yield of tiger nut solids 43 4.1.2 Nutrient composition of tiger nut products 45 4.1.3 Physical properties of tiger nut milk 48 4.1.3.1 Particle size distribution of extracted tiger nut milk 48 4.1.3.2 Colloidal stability of tiger nut milk 49 4.1.3.3 Colour stability of tiger nut milk 51 4.2 Stabilisation of tiger nut milk 53 4.2.1 Effects of enrichments on the stability of tiger nut milk 53 4.2.2 Effects of pH and temperature on the stability of enriched TNM 56 4.2.3 Effects of enrichments on the rheology of tiger nut milk 58 4.3 Tiger nut protein extraction and characterisation 60 4.3.1 Protein extraction and fractionation 60 4.3.2 Molecular mass of tiger nut protein 62 4.3.3 Thermal denaturation of tiger nut protein 63 4.3.4 Isoelectric point of tiger nut proteins 66 4.4 Properties of fermented tiger nut milk enriched with proteins 67 4.4.1 Acidification and gel formation during fermentation 67 4.4.2 Microbiological properties of fermented enriched tiger nut milk 70 4.4.3 Physico-chemical properties of fermented enriched tiger nut milk 71 4.4.4 Sensory properties of fermented tiger nut milk products 76 4.5 Microbial transglutaminase and fermented tiger nut milk property 77 4.5.1 Effects on tiger nut milk fermentation 77 4.5.2 Microbiological properties during storage of fermented product 81 4.5.3 Physico-chemical properties during storage of fermented product 83 4.5.4 Effects on colour of fermented tiger nut product 86 5. Conclusions and outlook 88 Bibliography 90 List of figures 111 List of tables 115 List of Publications 116 Poster and presentations 116
Erdmandeln (Cyperus esculentus L) haben ein hohes Potential als alternative Quelle Lebensmittelinhaltsstoffen. Allerdings gibt es nur in begrenztem Ausmaß Literatur über technologische Möglichkeiten zur Entwicklung von Mehrwert-Lebensmitteln wie fermentierter Erdmandelmilch. Daher wurden Strategien zur Herstellung und Verbesserung der Eigenschaften von fermentierter Erdmandelmilch zur Erzeugung laktosefreier joghurtähnlicher Produkte mit akzeptablen sensorischen Eigenschaften untersucht. Für die Extraktion der Erdmandelmilch wurde ein Nassmahlverfahren standardisiert und der Einfluss des Verfahrens auf die Nährstoffverteilung, die Farbeigenschaften und die kolloidale Stabilität der Milch analysiert. Als nächstes wurde Erdmandelmilch mit Proteinen und/oder Hydrokolloiden angereichert, und der Einfluss der Additive auf die physikalischen Eigenschaften des Extrakts bestimmt. Angereicherte Erdmandelmilch wurde mit klassischen Joghurtkulturen fermentiert, und die mikrobiologischen, physikalisch-chemischen und sensorischen Eigenschaften der Produkte wurden untersucht. Zusätzlich wurden Effekte der Anreicherung von Erdmandelmilch mit enzymatisch vernetzten Proteinen auf die mikrobiologischen und physikalisch-chemischen Eigenschaften bewertet. Eine höhere Nassmahlintensität verbesserte die Nährstoffzusammensetzung, die kolloidale Stabilität und die Farbe der Milch. Die Anreicherung erhöhte die Viskosität und Stabilität und führte nach der Fermentation zu homogenen gelartigen Produkten mit verbesserten mikrobiologischen, physikalisch-chemischen und sensorischen Eigenschaften im Vergleich zur fermentierten Erdmandelmilch. Mikrobielle Transglutaminase-vernetzte Proteine verbesserten die physikalischen Eigenschaften des fermentierten Produkts, insbesondere während der Lagerung. Dieses Produkt wäre in vielen Entwicklungsländern mit hoher Prävalenz von Laktoseintoleranz und begrenztem Zugang zu nahrhaften Lebensmitteln als Alternative von Interesse.:1. Introduction and aim 1 2. Literature review 4 2.1 Tiger nut, origin, nutritional value and food use 4 2.2 Tiger nut milk, preparation and nutrient composition 7 2.3 Colloidal characteristics of tiger nut milk 9 2.4 Factors accounting for the dispersion stability of tiger nut milk 10 2.5 Enhancing tiger nut milk stability 12 2.6 Properties of fermented tiger nut milk 17 2.7 Microbial transglutaminase and properties of fermented tiger nut milk 18 3. Methodology 21 3.1 Extraction and characterisation of tiger nut milk 21 3.1.1 Sample collection and preparation 21 3.1.2 Tiger nut milk extraction 21 3.1.3 Nutrient analysis of tiger nuts 22 3.1.4 Analysis of tiger nut products 23 3.1.5 Particle size distribution 24 3.1.6 Colloidal stability 25 3.1.7 Colour measurement 25 3.2 Stabilisation of tiger nut milk dispersion 26 3.2.1 Tiger nut milk preparation 26 3.2.2 Preparation of tiger nut milk enrichments 26 3.2.3 Gravitational stability of enriched tiger nut milk 27 3.2.4 Accelerated gravitational stability of enriched tiger nut milk 28 3.2.5 Viscosity of TNM mixtures 29 3.3 Extraction and characterisation of globular tiger nut proteins 29 3.3.1 Protein extraction and fractionation 29 3.3.2 Molecular mass of globular tiger nut proteins 31 3.3.3 Denaturation temperature of globular tiger nut proteins 32 3.3.4 Isoelectric point of globular tiger nut protein 33 3.4 Properties of fermented tiger nut milk enriched with proteins 34 3.4.1 Materials and Reagents 34 3.4.2 Preparation of plain and enriched tiger nut milk 34 3.4.3 Fermentation of plain and enriched tiger nut milk 35 3.4.4 Viable counts of starter cultures in fermented tiger nut milk systems 36 3.4.5 Chemical analysis of unfermented and fermented tiger nut milk 36 3.4.6 Physical analysis of fermented tiger nut milk products 37 3.4.7 Sensory analysis of fermented tiger nut milk products 38 3.5 Microbial transglutaminase and fermented tiger nut milk property 38 3.5.1 Preparation of plain and enriched tiger nut milk 38 3.5.2 Fermentation of plain and enriched tiger nut milk 39 3.5.3 Analysis of the enzymatically cross-linked proteins 39 3.5.4 Viable counts 40 3.5.5 pH and titratable acidity 40 3.5.6 Syneresis and viscosity 41 3.5.7 Colour of fermented tiger nut products 41 3.6 Statistical analysis 41 4. Results and discussion 43 4.1 Extraction and characteristics of tiger nut milk 43 4.1.1 Material recovery, mass transfer and yield of tiger nut solids 43 4.1.2 Nutrient composition of tiger nut products 45 4.1.3 Physical properties of tiger nut milk 48 4.1.3.1 Particle size distribution of extracted tiger nut milk 48 4.1.3.2 Colloidal stability of tiger nut milk 49 4.1.3.3 Colour stability of tiger nut milk 51 4.2 Stabilisation of tiger nut milk 53 4.2.1 Effects of enrichments on the stability of tiger nut milk 53 4.2.2 Effects of pH and temperature on the stability of enriched TNM 56 4.2.3 Effects of enrichments on the rheology of tiger nut milk 58 4.3 Tiger nut protein extraction and characterisation 60 4.3.1 Protein extraction and fractionation 60 4.3.2 Molecular mass of tiger nut protein 62 4.3.3 Thermal denaturation of tiger nut protein 63 4.3.4 Isoelectric point of tiger nut proteins 66 4.4 Properties of fermented tiger nut milk enriched with proteins 67 4.4.1 Acidification and gel formation during fermentation 67 4.4.2 Microbiological properties of fermented enriched tiger nut milk 70 4.4.3 Physico-chemical properties of fermented enriched tiger nut milk 71 4.4.4 Sensory properties of fermented tiger nut milk products 76 4.5 Microbial transglutaminase and fermented tiger nut milk property 77 4.5.1 Effects on tiger nut milk fermentation 77 4.5.2 Microbiological properties during storage of fermented product 81 4.5.3 Physico-chemical properties during storage of fermented product 83 4.5.4 Effects on colour of fermented tiger nut product 86 5. Conclusions and outlook 88 Bibliography 90 List of figures 111 List of tables 115 List of Publications 116 Poster and presentations 116