To see the other types of publications on this topic, follow the link: Food preservatives.
Dissertations / Theses on the topic 'Food preservatives'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Food preservatives.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Hall, Rosemary Linden. "Germination and outgrowth of spores Bacillus megaterium KM containing the Lux genes." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314754.
Full text
2
Thompson, Suzanne Claire. "Analysis of the weak acid stress response of Saccharomyces cerevisiae." Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271565.
Full text
3
Giffard, Catriona Julie. "The structure-function relations of the antimicrobial peptide nisin." Thesis, University of York, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319449.
Full text
4
Lee, Wai-kin Robin Dominic. "Determination of the optimal conditions and additives for the preservation of epigallocatechin gallate in bottled tea drinks." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41712419.
Full text
5
Thomas, Diane Allison. "Weak acid food preservatives and their mode of action on bacterial cells." Thesis, University of Aberdeen, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357481.
Full textAbstract:
The ability of microorganisms to withstand large environmental perturbations enables survival in a wide range of habitats including foodstuffs. The importance of elucidation of such survival strategies has been stressed. In order that microorganisms survive in such harsh environments control mechanisms must exist which enable the cell to grow under these conditions. Survival under such extremes would indicate adaptation. The mechanisms involved in such adaptation ultimately come from within the bacterial genome and are thought to be due to alterations in gene expression. The effect of altered external and internal pH was observed upon the recovery and habituation of wild type cells over a period of time and indicated that cells possess the ability to habituate. Using lacZ fusion strains and DNA supercoiling measurements enabled the effect of stress on ompF, ompC and proU gene expression to be assessed. It was demonstrated that ompC is expressed in response to both acidification of the external medium and the cytoplasm. The response of the cell to external and internal acidification is both quantitatively and qualitatively different. Only the acidification of the cytoplasm results in transient differential gene expression typical of gene induction. This process is carbon source dependent. In parallel studies it has been demonstrated that the expression of the supercoiling-dependent proU locus is repressed by acid (both cytoplasmic and environmental). Consistent with this observation is that reporter plasmids are more supercoiled when isolated from cells incubated under acid conditions and would lead to a reduction in gene expression. From these studies it can be concluded that regulation of ompC does not lie at the level of DNA supercoiling but is dependent on the effects exerted on the EnvZ/OmpR regulatory system and also suggests the role of a secondary internal sensing mechanism.
6
Snowball, Janet. "Development of the Ames test for studying mutagenicity of food preservatives." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394862.
Full text
7
Nasri, Hassen. "Mechanisms of inhibition of escherichia coli O157:H7 by food preservatives /." free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9988686.
Full text
8
李惟鍵 and Wai-kin Robin Dominic Lee. "Determination of the optimal conditions and additives for the preservation of epigallocatechin gallate in bottled tea drinks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41712419.
Full text
9
Engels, Christina [Verfasser]. "Structural and functional characterization of plant polyphenols as natural food preservatives / Christina Engels." Aachen : Shaker, 2012. http://d-nb.info/1066196842/34.
Full text
10
Holyoak, Caroline Dawn. "Mechanisms of weak acid adaptation in Saccharomyces cerevisiae." Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324945.
Full text
11
Altunakar, Bilge. "Food preservation by pulsed electric fields and selected antimicrobials." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Fall2007/b_altunakar_120507.pdf.
Full text
12
Roth, Steven M. "Sodium phosphate inhibition of the growth of selected foodborne spoilage yeasts." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/45177.
Full textAbstract:
Sodium phosphite was evaluated for inhibition of growth of spoilage yeasts in laboratory media and in two commercial carbonated beverages. In addition, the effects of pH and atmosphere in combination with sodium phosphite were also examined in laboratory media. Inhibition studies in laboratory media were performed with optimal or near optimal growth conditions for each yeast. Growth was monitored by measuring optical density at 600 nm. A time to significant growth was determined for experiments in laboratory media and was used to evaluate the effect that sodium phosphite and other test variables had on growth. A time to detectable growth was determined for experiments in commercial carbonated beverages and post incubation counts on observations with undetectable growth were used to evaluate the effects of sodium phosphite on yeast growth. Sodium phosphite was most effective in inhibiting growth of Zygosaccharomyces bailii, and less effective against Saccharomyces cerevisiae, and Saccharomyces uvarum respectively. Results from this investigation show the potential use of sodium phosphite as an antimicrobial food preservative has potential.Master of Science
13
Trickett, Michelle D. "Investigation of environmental microorganisms associated with the intrinsic microbial contamination of an alcohol-free mouthwash." Huntington, WV : [Marshall University Libraries], 2007. http://www.marshall.edu/etd/descript.asp?ref=810.
Full text
14
Van, der Merwe Iansha (Iansha Rosalia) 1975. "Characterization of thoeniicin 447 produced by Propionibacterium thoenii." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52729.
Full textAbstract:
Thesis (MSc)--University of Stellenbosch, 2002.ENGLISH ABSTRACT: Antimicrobial peptides continue to be one of the most important classes of food additives. The food industry is especially interested in the application of naturally occuring and biologically derived preservatives. Among the metabolites of industrial importance produced by propionibacteria are peptides called bacteriocins. Bacteriocins are ribosomally synthesized peptides with antagonistic activity against closely related microorganisms. Many microorganisms associated with food produce bacteriocins, which have stimulated interest in the use of these peptides as natural food preservatives. Numerous bacteriocins are produced by lactic acid bacteria, but only a few have been reported for propionibacteria. Since propionic acid bacteria have GRAS (generally regarded as safe) status, their metabolic compounds should be safe for human consumption. Propionibacterium thoenii 447, isolated from Emmentaler cheese, produces a bacteriocin-like peptide, named thoeniicin 447, with a narrow spectrum of activity. The peptide displays a bactericidal mode of action against Lactobacillus delbrueckii subsp. bulgaricus and a bacteriostatic action against Propionibacterium acnes. Optimal bacteriocin production was detected during the early stationary growth phase. The peptide is resistant to heat treatments of 60°C and 80°C for 15 and 30 min and to 100°C for 15 min, but loses 80% of its activity after autoclaving (10 min at 121°C). Thoeniicin 447 remains active after incubation in buffers with pH values ranging from 1-10. The peptide is inactivated by pepsin, pronase, a-chymotrypsin, trypsin and Proteinase K. Thoeniicin 447 was partially purified by ammonium sulfate precipitation, followed by SP-Sepharose cation exchange chromatography. The estimated size of thoeniicin 447, according to tricine-SDSPAGE, is approximately 6 kDa. Based on DNA sequencing, the mature peptide is 7130 Da in size and homologous to propionicin Tl produced by P. thoenii strain 419. Thoeniicin 447 is a relatively small, cationic and heat-stable peptide and can therefor be classified as a member of class II bacteriocins. These features are very similar to those of bacteriocins produced by lactic acid bacteria. However, no unique classification system has been proposed for bacteriocins of propionibacteria. As a member of the genus Propionibacterium, P. thoenii 447 is generally regarded as safe. This, together with the narrow spectrum of activity, particularly the action against P. acnes, heat tolerance of thoeniicin 447 and its activity over a wide pH range renders the peptide suitable for possible pharmaceutical applications.
AFRIKAANSE OPSOMMING: Antimikrobiese middels sal deurgaans beskou word as een van die belangrikste klasse van voedsel bymiddels. Die voedselindustrie is veral geïnteresseerd in die toepassing van preserveermiddels van 'n meer natuurlike en biologiese oorsprong. Onder die metaboliese produkte van industriële belang wat deur propionibakterieë geproduseer word is antimikrobiese peptiede (bakteriosiene). Bakteriosiene is ribosomaal-gesintetiseerde peptiede met 'n antagonistiese aktiwiteit teenoor naverwante bakterieë. Verskeie bakteriosiene word deur melksuurbakterieë geproduseer, terwyl slegs enkele vir propionibakterieë beskryf is. Baie van hierdie propionibakterieë word in die algemeen as veilig beskou en het GRAS status. Die metaboliete wat hulle produseer behoort dus veilig vir menslike gebruik te wees. Propionibacterium thoenii 447 is uit Emmentaler kaas geisoleer en produseer 'n bakteriosien-agtige peptied, naamlik thoeniicin 447 met 'n beperkte spektrum van aktiwiteit. Die peptied het 'n bakteriosidiese werking teenoor Lactobacillus delbrueckii subsp. bulgaricus en 'n bakteriostatiese werking teenoor Propionibacterium acnes. Optimum bakteriosien produksie is verkry tydens die vroeë stationêre groeifase. Die peptied is bestand teen hittebehandelings van 60°C en 80°C vir 15 en 30 min, asook 100°C vir 15 min, maar verloor 80% van sy aktiwiteit na outoklavering (lOmin by 121°C). Die peptied blyaktief na inkubasie in buffers van pH 1-10. Die peptied word deur pepsien, pronase, uchymotripsien, tripsien en Proteinase K geïnaktiveer. Thoeniicin 447 is met behulp van ammoniumsulfaat-presipitasie, gevolg deur SPSepharose katioon-uitruilchromatografie gedeeltelik gesuiwer. Skeiding op "n trisien-SDS poliakrielarnied-jel het 'n aktiewe band van ongeveer 6 kDa getoon. Volgens die DNA volgorde bepaling is thoeniicin 447, 7130 Da in grootte en homoloog aan Propionicin Tl, geisoleer vanaf P. thoenii stam 419. Thoeniicin 447 is 'n relatiewe klein, kationiese en hitte-bestande peptied en kan op grond hiervan as 'n lid van die klas II bakteriosiene geklassifiseer word. Hierdie eienskappe is soortgelyk aan die eienskappe van bakteriosiene geproduseer deur melksuurbakterieë. Tot op hede is geen klassifikasiesisteem vir die bakteriosiene van propionibakterieë voorgestel nie. As 'n lid van die genus Propionibacterium, word P. thoenii 447 in die algemeen as veilig beskou. Dit, tesame met die nou spektrum van aktiwiteit, veral teenoor P. acnes, die hittetoleransie van thoeniicin 447, asook die aktiwiteit oor 'n wye pH-grens, maak die peptied geskik vir moontlike farmaseutiese toepassings.
15
Shan, Bin. "Antioxidant and antibacterial capacities of spice and medicinal herb extracts and their potential application as natural food preservatives." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B4098784X.
Full text
16
Shan, Bin, and 單斌. "Antioxidant and antibacterial capacities of spice and medicinal herb extracts and their potential application as natural foodpreservatives." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B4098784X.
Full text
17
McGuire, Lynne. "Determination of the molecular and physiological basis of citric acid tolerance in spoilage yeast /." St Andrews, 2009. http://hdl.handle.net/10023/738.
Full text
18
Mosneaguta, Ruslan. "The effect of chemical preservatives on inhibition of potato browning, volatile organic compounds profile, and microbial inhibition." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1339015151.
Full text
19
Ḥasan, Ṣalāḥ 1964. "Methods to extend the mold free shelf life of pizza crusts." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27337.
Full textAbstract:
In this research, initial studies were done to determine the effect of various methods of presentation involving chemical preservatives, water activity ($ rm a sb{w}$), and modified atmosphere packaging (MAP) on mold growth in an agar model system. Results showed that preservatives could completely inhibit mold growth for 2-40d depending on concentration and pH used. Gas packaging (60% or 80% CO$ sb2$), oxygen absorbents, alone or in combination with potassium sorbate, could also inhibit mold growth for $>$40d at ambient storage temperature using a Response Surface Methodology (RSM) approach.The effects of various methods of applying potassium sorbate into pizza crusts via direct incorporation into the batter, surface spraying, and impregnation of packaging material with potassium sorbate to control mold spoilage of pizza crusts were also investigated. Results showed that the antimicrobial effect of potassium sorbate was negligible when the packaging material was impregnated with the inhibitor but more pronounced when it was incorporated directly into the dough or sprayed onto the product's surface. The inhibitory effect of potassium sorbate increased as both the pH and the inoculum level decreased.
Shelf life studies using low concentrations of potassium sorbate (1000 and 2000 p.p.m.) and MAP, alone and in combination with each other, showed that potassium sorbate, gas packaging or oxygen absorbents (Ageless FX) could extend the shelf life of pizza crusts and decrease the growth rate of molds, bacteria and yeast. Furthermore, when pizza crusts were packaged in 60% CO$ sb2$ or with an oxygen absorbent, in combination with potassium sorbate (1000-2000 p.p.m.), a shelf life of 42d was possible without compromising the sensory shelf life of the product. (Abstract shortened by UMI.)
20
Valencia, Chamorro Silvia Azucena. "Desarrollo de recubrimientos comestibles con actividad antifúngica en frutos cítricos." Doctoral thesis, Universitat Politècnica de València, 2009. http://hdl.handle.net/10251/6286.
Full textAbstract:
En la industria citrícola, las pérdidas económicas más importantes en poscosecha se deben las podredumbres verde y azul, causadas por los hongos Penicillium digitatum (Pers.:Fr.) Sacc. y Penicillium italicum Wehmer. Durante muchos años, se utilizaron ampliamente los fungicidas químicos para el control de estas enfermedades. Sin embargo, la preocupación de los consumidores por el uso excesivo y prolongado de estos productos para el control de las podredumbres ha orientado a los investigadores a buscar métodos alternativos no contaminantes que no depositen residuos peligrosos ni contaminen el ambiente.
El uso de películas y recubrimientos comestibles es un método respetuoso con el ambiente que incrementa la vida útil de muchos alimentos incluidas las frutas y verduras. Sin embargo, muy poca investigación se ha enfocado al desarrollo de recubrimientos comestibles compuestos con la adición de compuestos antifúngicos como un nuevo método para controlar las enfermedades poscosecha en frutos cítricos frescos.
El objetivo general de esta tesis doctoral fue desarrollar nuevos recubrimientos comestibles compuestos con la adición de aditivos alimentarios antifúngicos para el control de las podredumbres verde y azul en cultivares de cítricos comercialmente importantes. Primero, se desarrollaron las nuevas películas comestibles compuestas en base a hidroxipropil metilcelulosa (HPMC)-lípido con la adición de aditivos alimentarios o compuestos generalmente reconocidos como seguros (GRAS, por sus siglas en inglés), y se seleccionaron de acuerdo a su capacidad de formar emulsiones estables. Las películas se evaluaron por su actividad in vitro contra P. digitatum y P. italicum y sus propiedades mecánicas y de barrera (Capítulo 1). Luego, las emulsiones seleccionadas se usaron para pruebas in vivo en especies y cultivares de cítricos comercialmente importantes y se determinó su actividad antifúngica curativa (fruta recubierta después de la inoculación) y preventiva (fruta recubierta antes de la inoculación fungíca) contra las podredumbres verde y azul (Capítulo 2).Valencia Chamorro, SA. (2009). Desarrollo de recubrimientos comestibles con actividad antifúngica en frutos cítricos [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/6286
Palancia
21
Almeida, Maria Madalena Carneiro de. "Expressão heteróloga em Saccharomyces cerevisiae de genes de Zygosaccharomyces bailii envolvidos na resistência a conservantes alimentares." Master's thesis, ISA/UL, 2014. http://hdl.handle.net/10400.5/8203.
Full textAbstract:
Mestrado em Engenharia Alimentar - Qualidade e Segurança Alimentar - Instituto Superior de AgronomiaZygosaccharomyces bailii is one of the main spoilage yeasts and one of the biggest problems for Food Industry due to its high resistance to food preservatives, namely weak acids. In this work, we performed an evaluation of one mechanisms proposed for the increased resistance to benzoic and sorbic acid of Z. bailii: the decreased permeability to cations. More specifically, we evaluated the role of eight Z. bailii genes (OPI3, FEN1, SUR4, ISC1, ERG2, ERG4, ERG6, GAS1) on weak acid resistance. We cloned and characterized each Z.bailii genes by heterologous expression in S. cerevisiae strains without the respective gene. In order to characterize each transformant strain, we evaluated weak acid resistance (1-6 mM), intracellular pH, proton influx and extrusion through the plasma membrane and growth parameters (final biomass and yield) in YNB and in a commercial apple juice in non-adapted and in adapted cells to the acids. The most relevant results were obtained for ZbGAS1 gene, whose expression in S. cerevisiae improved growth (final biomass and cell yield) and increased proton pump activity in the presence of weak acid. These results point to possible cell wall composition changes as one of the mechanism possible involved in weak acid resistance
22
Zhang, Xueying. "Identification, properties, and application of enterocins produced by enterococcal isolates from foods." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1206069582.
Full text
23
Fossati, Ana Amélia Nunes. "Influência de aditivos alimentares sobre as Características físico-químicas, sensoriais e Microbiológicas do camarão Xyphopenaeus kroyeri." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/97879.
Full textAbstract:
Dada a importância do camarão para a economia do Brasil e as exigências cada vez mais acentuadas dos países importadores quanto à qualidade do produto final, bem como sua conservação para garantir a oferta de um produto de qualidade aos consumidores, a indústria pesqueira vem utilizando diversas classes de aditivos alimentares: anti-melanóticos, antioxidantes e anti-microbianos. Desta forma, o presente trabalho objetivou avaliar o efeito dos aditivos alimentares: cloreto de sódio, metabissulfito de sódio, nitrito de sódio e ácido cítrico sobre a vida-de-prateleira do camarão Xyphopenaeus kroyeri resfriado, além de avaliar a ação anti-melanótica destes aditivos por 12 dias pós-captura através de escala de graus de melanose. Os camarões dos tratamentos controle (sem aditivo), com metabissulfito de sódio e com nitrito de sódio mantiveram seus valores de pH constantes até o 12º dia de armazenamento e os valores de pH demonstraram correlações positivas com a contagem de mesófilos (r=0,6633;p=0,0070), e com valores de BNVT (r=0,7173; p=0,0026). Durante o período avaliado, os camarões que apresentaram menor produção de bases nitrogenadas voláteis totais foram os imersos em nitrito de sódio (1%), com valores crescentes de 48,20±25,03 no dia 1; 128,00±25,45 no dia 7; 161,50±19,09 no dia 10 e 230,50±33,23 no dia 12. Os valores de força de cisalhamento não exibiram diferença (p>0,05) entre os tratamentos e entre os dias de armazenamento. As bactérias mesófilas e psicotróficas apresentaram as menores contagens nos camarões imersos em cloreto de sódio a 2% e nitrito de sódio a 1%. Não houve crescimento de coliformes termotolerantes, estando todos os tratamentos de acordo com a legislação vigente. O tratamento com metabissulfito de sódio foi o que apresentou menores graus de melanose. Na análise sensorial, não foram encontradas diferenças significativas entre os tratamentos, demonstrando que o uso de aditivos pode auxiliar na preservação da qualidade do camarão sem alterar as características sensoriais do mesmo.Given the importance of shrimp to the economy of Brazil and progressively greater demands of importing countries as to the quality of the final product as well as its conservation to ensure the provision of a quality product to consumers, the fishing industry has been using various classes’ food additives: non-melanotics, antioxidants and antimicrobials. Thus, this study aimed to evaluate the effect of food additives: sodium chloride, sodium metabisulfite, sodium nitrite and citric acid on the shelf- life of shrimp Xyphopenaeus kroyeri cold, and to evaluate the anti-melanosis action of these additives by 12 days post-capture through melanosis scale degrees. The shrimps of the control treatment (no additive), with sodium metabisulfite and sodium nitrite maintained their pH constant until the 12th day of storage, add the pH values showed positive correlations with counts of mesophilic (r2= 0.6633, p = 0.0070) and with BNVT values (r2= 0.7173, p = 0.0026). During the study period, the shrimp that showed low production of volatile nitrogenous bases were immersed in sodium nitrite (1 %) , with increasing values of 48.20 ± 25.03 on day 1; 128.00 ± 25.45 on day 7; 161.50 ± 19.09 on day 10 and 230.50 ± 33.23 on day 12. Values of shear force showed no difference (p > 0.05) between treatments and between days of storage. The mesophilic and psicotrophic showed the lowest counts shrimps immersed in sodium chloride 2% and sodium nitrite 1%. There was no presence of coliforms growth, with all treatments in accordance with current legislation. Treatment with sodium metabisulfite showed the lowest degree of melanosis. In sensory analysis, no significant differences between treatments were found, demonstrating that the use of additives can assist in preserving the quality of the shrimp without altering the sensory characteristics.
24
Souza, Alex Sandra Nascimento De. "Influence of chemicals preservative on the determination of the total antioxidant activity in tropical juice acerola." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10918.
Full textAbstract:
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoThe food industry uses chemical additives to extend the shelf life of its products and maintain their sensory and microbiological characteristics acceptable. However, the presence of preservatives in foods may interfere in the quantification of total antioxidant activity. Therefore, this study aimed to evaluate the influence of food preservatives on total antioxidant activity and on the sensory and microbiological quality of acerola tropical juice. The fruits were washed, sanitized (200 ppm sodium hypochlorite), pulped and then were formulated with water and its specific preservatives. The juices were heat treated (90ÂC/60 seconds) and hot filled in glass bottles, which were closed, cooled until 35ÂC and stored at 25ÂC for 180 days. The formulations tested were: control juice without additive (C); juice with addition of 0.004 g/100 mL of sodium metabisulphite (SMS); juice with addition of 0.08 g/100 mL of potassium sorbate (SSP); juice added of 0.05 g/100 mL of sodium benzoate (SBS); juice added of 0.002 g/100 mL of sodium metabisulfite and 0.04 g/100 mL of potassium sorbate S(MS+ SP); juice with addition of 0.002 g/100 mL of sodium metabisulfite and 0.025 g/100 mL of sodium benzoate S(MS + BS). It was carried out chemical determinations for ascorbic acid, total carotenoids, total anthocyanins, total extractable polyphenolics and total antioxidant activity by ABTS and DPPH methods. Commercial sterility testing was performed on samples to determine the hygienic and sanitary processing and to check for any microbiological changes. In sensory acceptance tests were used acerola nectars, prepared by dilution from the acerola tropical juice and added sucrose to obtain 11 ÂBrix, using a 9-point hedonic scale for flavor, color, aroma, sweetness, appearance, body and overall impression. The experiments were performed at three time points (0, 90 and 180 days) and the determinations were made in triplicate. The results were analyzed by the interaction between the juice type and storage time. Regarding anthocyanins content, all samples showed an average of 1.0 mg/100mL (P> 0.05). The acid ascorbic contents remained stable during the storage and ranged from 256.22 mg/100mL (C juice) to 301mg/100mL (SMS and SSP juices). The total carotenoid in treatments with or without preservatives did not vary significantly among themselves, with mean values of 0.04 mg/100mL. The yellow flavonoids showed no significant difference between the juice type (P> 0.05), averaging 5.30 mg/100 mL. For soluble dark pigments, SMS obtained the lowest range in absorbance at 90 days time (0.170 to 0.240), and greater variation for the control juice (from 0.230 to 0.320). All samples showed high losses of phenolics during storage, observing greater losses at times of 0 and 90 days, which ranged from 36.59% for S(BS + MS) and 42.97% for SMS. There was a significant variation of total antioxidant activity with time by the DPPH test (P≤0.05). The values ranged from 877.41 to 978.44 g/g DPPH for C and SMS juices, respectively. A similar behavior was observed for contents analyzed by the ABTS testing: 58.46 mM Trolox/g for SMS and 49.80 mM Trolox/g for control juice. A significant and positive correlation was verified between polyphenols and ABTS (r = 0.78) and DPPH (r = 0.44); anthocyanins and ABTS (r = 0.39) and DPPH (r = 0.44). Yellow flavonoids and ABTS and DPPH assays were negatively and significantly correlated (r = -0.83 and r = -0.52), respectively. There was no significant correlation between ascorbic acid and ABTS and DPPH assays. There was no significant interaction between any treatment and storage time (P> .05). Sodium metabisulphite and its combinations did not influence sensorial acceptance of acerola nectars, with assessments within the acceptable range for all analyzed attributes along storage time. The potassium sorbate and sodium benzoate singly were the additives that contributed most to a higher rejection sensory of products. The employed chemical preservatives, associated with the heat treatment, were effective for maintaining the commercial sterility of acerola tropical juices.
A indÃstria de alimentos utiliza-se de conservantes quÃmicos para prolongar a vida Ãtil de seus produtos e manter suas caracterÃsticas sensoriais e microbiolÃgicas aceitÃveis. Contudo a presenÃa desses conservantes nos alimentos pode interferir na quantificaÃÃo da atividade antioxidante total. Portanto, este trabalho objetivou avaliar a influÃncia dos conservantes alimentares na atividade antioxidante total, na qualidade sensorial e microbiolÃgica de sucos tropicais de acerola. As frutas foram lavadas, sanitizadas (200mg/L de cloro ativo) e despolpadas, em seguida, formuladas com Ãgua e seus conservantes especÃficos. Os sucos foram tratados termicamente (90ÂC/60 segundos) e acondicionados a quente em garrafas de vidro, que foram fechadas, resfriadas atà 35ÂC e armazenadas à temperatura de 25ÂC por 180 dias. As formulaÃÃes testadas foram: suco controle, sem aditivo (C); suco com adiÃÃo de 0,004 g de metabissulfito de sÃdio/100 mL (SMS); suco com adiÃÃo de 0,08g sorbato de potÃssio /100 mL de (SSP); suco adicionado de 0,05g de benzoato de sÃdio /100 mL (SBS); suco com 0,002g de metabissulfito de sÃdio e 0,04 g/100 mL de sorbato de potÃssio/100 mL S(MS+SP)); suco com adiÃÃo de 0,002g/100 mL de metabissulfito de sÃdio e 0,025 g/100 mL de benzoato de sÃdio S(MS+BS). Foram realizadas determinaÃÃes quÃmicas de Ãcido ascÃrbico, carotenÃides totais, antocianinas totais, polifenÃis extraÃveis totais e quantificaÃÃo da atividade antioxidante total pelos mÃtodos ABTS e DPPH. Foi realizado o teste de esterilidade comercial nas amostras para determinar as condiÃÃes higiÃnico-sanitÃrias do processamento e verificar as possÃveis alteraÃÃes microbiolÃgicas. Os testes sensoriais de aceitaÃÃo foram utilizados nÃctares de acerola, preparados por diluiÃÃo a partir do suco tropical de acerola e adicionado de sacarose atà obtenÃÃo de 11 ÂBrix, os quais foram avaliados quanto aos atributos impressÃo global, cor, aparÃncia, aroma, doÃura, sabor e corpo utilizando uma escala hedÃnica estruturada de nove pontos. Os experimentos foram realizados em trÃs tempos (0, 90 e 180 dias) e realizados em triplicata. Os resultados foram tratados por anÃlise de interaÃÃo entre os diferentes tratamentos e tempo de armazenamento. Para o teor de antocianinas, todas as amostras apresentaram mÃdia de 1,0mg/100g (P>0,05). O teor de Ãcido ascÃrbico se manteve estÃvel durante o armazenamento, variando de 256,22 mg/100mL para o suco C, a 301mg/100mL, para os sucos SMS e SSP. Os teores de carotenÃides totais nos tratamentos com ou sem conservantes nÃo diferiram entre si (P>0,05), apresentando valor mÃdio de 0,04mg/100mL. Os flavonoides amarelos nÃo apresentaram diferenÃa significativa (P>0,05), apresentando mÃdia de 5,30mg/100mL. Para pigmentos escuros solÃveis o SMS obteve a menor variaÃÃo na absorbÃncia no tempo de 90 dias (0,170 a 0,240), e a maior variaÃÃo para o suco controle (0,230 a 0,320). Todas as amostras apresentaram perdas elevadas de fenÃlicos durante o armazenamento, observando-se perdas maiores entre 0 e 90 dias, que variaram de 36,59% para S(MS+BS) e 42,97% para SMS. Houve variaÃÃo significativa com o tempo para a atividade antioxidante total pelo ensaio DPPH (P≤0,05). Os valores variaram entre 877,41 e 978,44 g/g DPPH para os sucos C e SMS, respectivamente. Comportamento semelhante foi observado para os teores analisados pelo mÃtodo ABTS, observando-se para o SMS, 58,46 ÂM Trolox/g; e para o suco controle, 49,80 ÂM Trolox/g. A correlaÃÃo positiva e significativa foi verificada entre polifenÃis e o ensaio ABTS (r = 0,78) e para DPPH (r = 0,44). Antocianinas totais e ABTS (r = 0,39) e DPPH (r = 0,44). Os flavonÃides amarelos e os ensaios ABTS e DPPH se correlacionaram negativamente e significativamente (r = -0,83 e r= -0,52; respectivamente). NÃo foi observada interaÃÃo significativa entre os tratamentos e os tempos de armazenamento (P > 0,05). O metabissulfito de sÃdio e suas combinaÃÃes nÃo influenciaram na aceitaÃÃo sensorial dos nÃctares de acerola, com avaliaÃÃes dentro da faixa de aceitaÃÃo para todos os atributos analisados ao longo do tempo de armazenamento. Os aditivos sorbato de potÃssio e benzoato de sÃdio isoladamente contribuÃram para uma maior rejeiÃÃo sensorial dos produtos. Os conservantes quÃmicos utilizados, associados ao tratamento tÃrmico empregado, foram eficientes para a manutenÃÃo da esterilidade comercial dos sucos tropicais de acerola.
25
Caetano, Priscilla Kárim 1979. "Desenvolvimento e aceitabilidade de compota de figo convencional e diet /." Botucatu, 2016. http://hdl.handle.net/11449/137891.
Full textAbstract:
Orientador: Rogério Lopes VieitesBanca: Aline de Oliveira Garcia
Banca: Eliane Maria Ravasi Stéfano Simionato
Banca: Roseli Aparecida Claus Bastos Pereira
Banca: Regina Daiuto Bastos
Resumo: Os figos são comercializados in natura ou processados na forma de doces. A preocupação com a saúde, especialmente à obesidade ou diabetes, tem feito o consumidor buscar opções menos calóricas para manter o prazer de ingerir alimentos doces. A elaboração de produtos com sabor idêntico ao convencional é de grande importância para aceitação destes produtos. O objetivo deste projeto foi desenvolver protocolos de fabricação de compota de figo diet visando o aproveitamento tecnológico e agregação de valor ao fruto respondendo aos interesses da Associação Agrícola de Valinhos e Região. Foram elaboradas compotas de figo verde avaliando diferentes edulcorantes. As formulações da calda foram: calda de açúcar (TA); Sorbitol (TS); Eritritol (TE); Sorbitol e Erititol (TSE); Steviosídeo (TST); Ciclamato de Sódio, Sucralose e Sacarina Sódica (TCSuSa); Ciclamato sódico e Sacarina sódica (TSC); Acessulfame-K e Sucralose (TAcSu); Steviosídeo, Sacarina Sódica e Ciclamato de Sódio (TSSC). Os figos in natura e as compotas foram avaliados quanto teores de sólidos solúveis oBrix, pH, acidez titulável, açúcar redutor-AR e açúcar redutor total-ART, umidade, proteínas, lipídeos e cinzas. Também foram avaliados quanto a cor instrumental, textura, análises microbiológicas e avaliação sensorial através dos testes de ordenação e teste afetivo. Para a qualidade das compotas foram determinados o peso bruto, peso líquido e peso drenado, vácuo e contagem de número de figos no pote. Os valores de todos os atributos físico-químicos avaliados estão de acordo com a literatura e legislação para este tipo de produto. A coloração do figo in natura e da compota mostraram que houve alteração na cor quando os mesmos sofreram tratamento térmico, causando modificação da cor natural dos frutos. Não ocorreu contaminação microbiológica nas compotas e se apresentaram em ...
Abstract: Figs are marketed fresh or processed into sweets. Concern for health, especially with obesity or diabetes, have made consumers look for low-calorie options to keep the pleasure of eating sweet foods. The preparation of products identical to conventional taste is of great importance for acceptance of these products. The objective of this project was to develop diet fig compote manufacturing protocols to technological use and add value to fruit responding to the interests of the Agricultural Association of Valinhos and Region. green fig jam evaluating different sweeteners were prepared. The slurry formulations were: syrup (TA); Sorbitol (TS); Erythritol (TE); Sorbitol and Erititol (TSE); Steviosídeo (TST); Sodium cyclamate, sucralose and saccharin Sodium (TCSuSa); sodium cyclamate and Saccharin (TSC); Acesulfame-K and sucralose (TAcSu); Steviosídeo, Saccharin Sodium and Sodium cyclamate (TSSC). Figs fresh and the jams were evaluated for soluble solids ° Brix, pH, titratable acidity, reducing sugar and sugar-AR full-ART reducer, moisture, protein, lipids and ash. They were also evaluated for instrumental color, texture, microbiological analysis and sensory evaluation through the ordering and affective test tests. For the quality of jams were determined the gross weight, net weight and drained weight, vacuum and number of figs count the pot. The values of all evaluated physico-chemical attributes are consistent with literature and rules for this type of product. Staining fig fresh and compote showed that there was a change in color when they have undergone heat treatment, causing modification of the natural color of the fruit. There was no microbiological contamination in jams and presented in satisfactory sanitary conditions. In sensory analysis, the jams of TA treatments TCSuSa and TSSC were selected in order to test for sweetness and affective test only TA and TCSuSa jams obtained higher scores for...
Doutor
26
Snyman, Marina J. "Isolation and antimicrobial susceptibility characterisation of listeria SPP. in selected food premises in Central South Africa." Thesis, Bloemfontein : Central University of Technology, Free State, 2011. http://hdl.handle.net/11462/138.
Full textAbstract:
Thesis (M. Tech. Environmental health) -- Central University of technology, Free State, 2011Microbial pathogens play an important role in the food industry where they could cause disease and subsequently significant economic losses. Limited information is available on the situation with regard to Listeria in food products in South Africa. However, much research is being done in the rest of the world on Listeria indicating serious problems as a result of resistance development against various antimicrobial agents, including the organic acids. It is hypothesised that the situation with regard to resistance development may be more serious than generally admitted. Isolation of 200 different food samples was done by using a slightly modified EN ISO 11290-1/A1:2004 standard method. Identification of presumptive positive colonies was confirmed as Listeria by API (Analytical profile index) Listeria. API positive cultures were subjected to 16S rDNA sequencing to compare and confirm identification. Isolates and standard strains were screened for resistance to food preservatives such as organic acids and antibiotics used in the current treatment regime for Listeria infections. The organisms evaluated included isolated strains namely Listeria monocytogenes, Listeria welshimeri, Listeria innocua and their corresponding ATCC (American type culture colletion) strains. An agar dilution method as described by the Clinical and Laboratory Standard Institute (CLSI) was used to determine the minimum inhibitory concentrations (MICs) of 11 antibiotics and 13 organic acids and salts for all the isolates. Overall antibiotic susceptibility patterns of all the isolates indicated high level susceptibility to all the antibiotics tested. Susceptibility to all the organic acids was notably reduced at pH 7 in all the isolates and control strains. Eight highly susceptible strains were selected for induction and represented each of the species isolated. These isolates were exposed to increasing concentrations of three antibiotics and three organic acids. MICs were again determined for all the induced strains for five antibiotics and three organic acids. Proteins extracted from the induced strains were separated on discontinuous SDS-PAGE slab gels to generate total protein profiles. Notable variations were observed in MICs, although induction with antibiotics as well as organic acids did not result in general resistance development. However, evidence was provided that continuous exposure to antimicrobial agents may cause Listeria spp. to develop resistance to different antimicrobial agents. Further research and in depth studies on mechanisms involved in the development of resistance to food preservatives would, therefore, be required. Finally, it is concluded that Listeria monocytogenes may be a possible threat in the Central South African food industry, which deserves more attention. The situation may actually pose a problem that is overseen, because only a small percentage of people that get sick from food, would seek medical advice.
27
Crona, Elna, and Nathalie Johnsson. "Jämförelse av olika konserveringsmedel genom belastningstest i ett flytande livsmedel." Thesis, Högskolan Kristianstad, Fakulteten för naturvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hkr:diva-20949.
Full textAbstract:
Inledning En tredjedel av den mat som produceras i världen slängs (United Nations Development Programme [UNDP], 2020) och de livsmedelsförstörande mikroorganismerna är ett vanligt förekommande problem och en bidragande orsak till det globala matsvinnet (Snyder & Worobo, 2018). Livsmedelsindustrin använder därför olika hurdletekniker för att minimera risken för tillväxt av förskämningsorganismer (Snyder & Worobo, 2018). En strategi för att kontrollera om olika hurdletekniker uppfyller sitt syfte är att utsätta ett livsmedel för ett belastningstest. Syfte Syftet med studien var att genom ett belastningstest i ett flytande livsmedel jämföra konserveringsmedlen lingonjuice och kaliumsorbat + natriumbensoat samt att undersöka produktens fysikaliska och kemiska förändringar över tid. Material och metod Ett flytande livsmedel (n = 73 á 180 ml) inokulerades i ett belastningstest med log 2–3 mikroorganismer per ml livsmedel. Därefter tillsattes konserveringsmedlen lingonjuice (n = 24) eller kaliumsorbat + natriumbensoat (n = 25). En tredjedel av proverna (n = 24) lämnades utan konserveringsmedel. Provtagning för analys av tillväxt, färg, pH och viskositet (mPas) utfördes vid 0, 14 och 30 dagar efter livsmedlet inokulerats med mikroorganismer. Resultat Resultatet visade mikrobiell tillväxt i samtliga livsmedel vid dag 0. Dag 14 identifierades tillväxt i livsmedlet med kaliumsorbat + natriumbensoat samt lingonjuice. Vid analysen på dag 30 identifierades tillväxt i livsmedlet med kaliumsorbat + natriumbensoat och i livsmedlet utan konserveringsmedel. Över tiden skedde även fysikaliska förändringar i viskositet och kemiska förändringar av pH-värdet. Gällande färg skedde enbart marginella förändringar. Slutsats Resultatet av belastningstestet visade att lingonjuice är det konserveringsmedel som har bäst effekt med avseende på produktstabilitet genom att hämma tillväxt av tillsatta mikroorganismer. Resultaten av de fysikaliska mätningarna visade på förändringar över tid med avseende på viskositet. Färg visade enbart minimala förändringar. Resultatet av den kemiska mätningen visade på förändringar av pH-värdet över tid.Introduction One third of food produced in the world is discarded (United Nations Development Program [UNDP], 2020) and food-destroying microorganisms are a common problem and a contributing cause of global food waste (Snyder & Worobo, 2018). The food industry therefore uses various hurdle techniques to minimize the risk of growth of spoilage organisms (Snyder & Worobo, 2018). One strategy to check whether different hurdle techniques meet their purpose is to expose foods in a challenge test. Aim The aim of the study was to compare the preservatives lingonberry juice and potassium sorbate + sodium benzoate and examine any physical and chemical changes over time through a challenge test on a liquid food product. Material and method A liquid food (n = 73 á 180 ml) was inoculated in a challenge test with log 2-3 microorganisms per ml food. Thereafter preservatives lingonberry juice (n = 24) or potassium sorbate + sodium benzoate (n = 25) were added. One third of the samples (n = 24) were left without preservatives. Sampling for analysis of growth, color, pH and viscosity (mPas) was performed at 0, 14 and 30 days after the food was inoculated with microorganisms. Results The results showed microbiological growth in all food products at day 0. Day 14 growth were found in the food with potassium sorbate + sodium benzoate and lingonberry juice. By the analysis on day 30 growth in the food with potassium sorbate + sodium benzoate and in the food without preservatives were showed. Over time physical changes of viscosity and chemical changes of pH occurred. Regard to color only marginal changes occurred. Conclusion The result of the challenge test showed that lingonberry juice is the preservative that has the best effect regard to product stability through inhibiting the added microorganisms. The results of the physical measurements showed changes regard to viscosity over time. Color only showed marginal changes. The result of the chemical measurement showed changes of pH over time.
28
Pereira, Ana Bárbara Ferreira Neves Quatorze. "Flavonoid-cyclodextrin complexes and their incorporation in milk products." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15325.
Full textAbstract:
Mestrado em Bioquímica - Bioquímica AlimentarThe presented work describes the inclusion of the flavonoid quercetin into β and γ cyclodextrins and the subsequent incorporation of such complexes into a dairy product — fresh cheese. The characterization of the complexes was made using various techniques, and antioxidant assays were also performed to assess their antioxidant and anti-lipid peroxidation capacity in comparison to quercetin. The incorporation of the complexes in fresh cheese resulted in the modification of some of the characteristics of the food product, having these also presented promising antioxidant capacity.
O trabalho apresentado descreve a inclusão do flavonóide quercetina nas ciclodextrinas β e γ, com posterior incorporação dos complexos em laticínios, nomeadamente queijo fresco. A caracterização dos complexos de inclusão foi feita utilizando várias técnicas, tendo sido também realizados ensaios antioxidantes para avaliar a sua capacidade antioxidante e de anti-peroxidação lipídica, em comparação com a quercetina. A incorporação dos complexos no queijo fresco resultou na modificação de algumas características do produto alimentar, tendo estes complexos também apresentado uma promissora capacidade antioxidante.
29
Gusmão, Viviane Vieira [UNESP]. "Qualidade microbiológica e ocorrência de leveduras em leite pasteurizado tipos A, B e C." Universidade Estadual Paulista (UNESP), 2005. http://hdl.handle.net/11449/88397.
Full textAbstract:
Made available in DSpace on 2014-06-11T19:23:27Z (GMT). No. of bitstreams: 0
Previous issue date: 2005-03-04Bitstream added on 2014-06-13T19:09:13Z : No. of bitstreams: 1
gusmao_vv_me_sjrp.pdf: 467989 bytes, checksum: f6fb70f81cc15aa3029140a597f0de22 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
No Brasil, o leite possui uma posição de destaque, tanto do ponto de vista social como do econômico. Devido a sua composição peculiar rica em proteínas, gorduras, carboidratos, sais minerais e vitaminas, é considerado como um excelente meio de cultura, pois constitui um ambiente adequado para o desenvolvimento de vários microrganismos. A contaminação microbiana altera a qualidade do alimento e pode agir como veículo de microrganismos patogênicos, que podem provocar o desenvolvimento de doenças infecciosas ou intoxicações alimentares, que colocam em risco a saúde do consumidor e levam à condenação do leite, além da perda da qualidade nutricional do produto. O leite é freqüentemente relacionado com surtos de toxinfecções alimentares, o que justifica a necessidade de avaliações constantes de sua qualidade garantindo a sua condição de consumo. Neste trabalho foram coletadas 23 amostras de leite pasteurizado tipos A, B e C, obtidas no comércio varejista da região de São José do Rio Preto - SP, que foram submetidas as seguintes análises microbiológicas: contagem de bactérias aeróbias mesófilas, enumeração de bolores e leveduras, determinação do Número Mais Provável (NMP) de coliformes totais e fecais, pesquisa de Escherichia coli e de Salmonella spp. Das amostras de leite analisadas foram isoladas 31 culturas de leveduras, submetidas às provas taxonômicas, morfológicas, fisiológicas e de assimilação de diversas fontes de carbono. De acordo com os resultados obtidos, observou-se que apenas 2 (8,70%) amostras apresentaram coliformes fecais acima do limite da legislação, resultado este, inferior aos diversos trabalhos encontrados em leite pasteurizado desenvolvidos em diferentes regiões do Brasil. A presença de Escherichia coli foi constatada em apenas 3 amostras, sendo todas do tipo C. A de Salmonella spp não foi verificada em nenhuma...
In Brazil, milk has a prominent position, as much of social point of view as of economic, due to its particular composition rich in proteins, fats, carbohydrates, mineral salts and vitamins, and consequently it is considered like an excellent medium, because it s an adequate atmosphere for the development of several microorganism. The microbial contamination changes the food quality, so that it may act like vehicle of pathogenic microorganism, promoting disease or food poisoning, risking consumer s health and milk may be condemned; besides the loss of product s nutritional quality. Milk is frequently related to outbreaks of food toxinfection, what justify the need for constant evaluations of its quality as well as the guarantee of its condition of consumption. In this study 23 samples of kinds A, B and C pasteurized milk were obtained from the retail trade of São José do Rio Preto (SP) region and were done the following microbiological analyses: counting of mesophilic aerobic bacteria, listing of molds and yeasts, determination of most probable number (MPN) of total coliforms and fecal coliforms, research of E. coli and Salmonella spp.. Thirty one yeast cultures were isolated from the samples. They were submitted to taxonomic, morphological, and physiological tests and to carbon source assimilation test. According to the results obtained, only 2 (8.70%) had fecal coliforms above the regulation limit. The percentage out of the microbiological standard (8.70%) was lower than several studies found in pasteurized milk, developed in different regions of Brazil. E. coli was detected in 3 samples of kind C. Salmonella spp. was not detected in any sample analyzed, what is in accordance with the current regulation. In conclusion, most of the samples (91.30%) had coliforms a 45°C 4 MPN/mL, xii consequently were labeled as products in satisfactory sanitary conditions, therefore products...(Complete abstract click electronic access below)
30
Gusmão, Viviane Vieira. "Qualidade microbiológica e ocorrência de leveduras em leite pasteurizado tipos A, B e C /." São José do Rio Preto : [s.n.], 2005. http://hdl.handle.net/11449/88397.
Full textAbstract:
Orientador: Fernando Leite HoffmannBanca: Vanerli Beloti
Banca: Crispin Humberto Garcia Cruz
Resumo: No Brasil, o leite possui uma posição de destaque, tanto do ponto de vista social como do econômico. Devido a sua composição peculiar rica em proteínas, gorduras, carboidratos, sais minerais e vitaminas, é considerado como um excelente meio de cultura, pois constitui um ambiente adequado para o desenvolvimento de vários microrganismos. A contaminação microbiana altera a qualidade do alimento e pode agir como veículo de microrganismos patogênicos, que podem provocar o desenvolvimento de doenças infecciosas ou intoxicações alimentares, que colocam em risco a saúde do consumidor e levam à condenação do leite, além da perda da qualidade nutricional do produto. O leite é freqüentemente relacionado com surtos de toxinfecções alimentares, o que justifica a necessidade de avaliações constantes de sua qualidade garantindo a sua condição de consumo. Neste trabalho foram coletadas 23 amostras de leite pasteurizado tipos A, B e C, obtidas no comércio varejista da região de São José do Rio Preto - SP, que foram submetidas as seguintes análises microbiológicas: contagem de bactérias aeróbias mesófilas, enumeração de bolores e leveduras, determinação do Número Mais Provável (NMP) de coliformes totais e fecais, pesquisa de Escherichia coli e de Salmonella spp. Das amostras de leite analisadas foram isoladas 31 culturas de leveduras, submetidas às provas taxonômicas, morfológicas, fisiológicas e de assimilação de diversas fontes de carbono. De acordo com os resultados obtidos, observou-se que apenas 2 (8,70%) amostras apresentaram coliformes fecais acima do limite da legislação, resultado este, inferior aos diversos trabalhos encontrados em leite pasteurizado desenvolvidos em diferentes regiões do Brasil. A presença de Escherichia coli foi constatada em apenas 3 amostras, sendo todas do tipo C. A de Salmonella spp não foi verificada em nenhuma...(Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In Brazil, milk has a prominent position, as much of social point of view as of economic, due to its particular composition rich in proteins, fats, carbohydrates, mineral salts and vitamins, and consequently it is considered like an excellent medium, because its an adequate atmosphere for the development of several microorganism. The microbial contamination changes the food quality, so that it may act like vehicle of pathogenic microorganism, promoting disease or food poisoning, risking consumers health and milk may be condemned; besides the loss of products nutritional quality. Milk is frequently related to outbreaks of food toxinfection, what justify the need for constant evaluations of its quality as well as the guarantee of its condition of consumption. In this study 23 samples of kinds A, B and C pasteurized milk were obtained from the retail trade of São José do Rio Preto (SP) region and were done the following microbiological analyses: counting of mesophilic aerobic bacteria, listing of molds and yeasts, determination of most probable number (MPN) of total coliforms and fecal coliforms, research of E. coli and Salmonella spp.. Thirty one yeast cultures were isolated from the samples. They were submitted to taxonomic, morphological, and physiological tests and to carbon source assimilation test. According to the results obtained, only 2 (8.70%) had fecal coliforms above the regulation limit. The percentage out of the microbiological standard (8.70%) was lower than several studies found in pasteurized milk, developed in different regions of Brazil. E. coli was detected in 3 samples of kind C. Salmonella spp. was not detected in any sample analyzed, what is in accordance with the current regulation. In conclusion, most of the samples (91.30%) had coliforms a 45°C 4 MPN/mL, xii consequently were labeled as "products in satisfactory sanitary conditions, therefore "products...(Complete abstract click electronic access below)
Mestre
31
Namor, Omar G. "Sorbic acid interaction with sulphur dioxide in model food systems." Thesis, University of Surrey, 1987. http://epubs.surrey.ac.uk/847780/.
Full textAbstract:
Sorbic acid and sulphur dioxide are often used together, as preservatives,in many foods. Sorbic acid is known to undergo degradation in aqueous solutions, and this degradation appears to be accelerated in the presence of sulphur dioxide. The interaction between sorbic acid and sulphur dioxide is the subject of this thesis. The work is subdivided into five chapters, as follows: The first chapter deals with the chemistry of sorbic acid acid and sulphur dioxide. The second chapter describes a study of the degradation products of sorbic acid, in aqueous systems, in the presence of sulphur dioxide and a possible mechanism for the occurrence of these products is proposed. Chapter three deals with the preparation and degradation of 6-[[13]C] sorbic acid in order to find evidence for, or against, the mechanism proposed in chapter two. It also gives details of syntheses attempted in order to obtain 6-[[13]C] sorbic acid. The interaction of sorbic acid and sulphur dioxide in real food systems is the subject of the fourth chapter. The food systems studied were mayonnaise, tomato puree, orange juice and cottage cheese. The effect of packaging on the rate of degradation of sorbic acid was also investigated. The final chapter deals with a microbiological study of two homologues of sorbic acid, 2,4-heptadienoic acid, 2,4-octadienoic acid. The fungicidal activity of these two compounds, towards selected fungi, was analysed. 4-0xobut-2-enoic acid, a degradation product of sorbic acid in aqueous systems, was also analysed as a possible fungistat.
32
Herculano, Emanuele Duarte. "Nanoencapsulated Eucalyptus staigeriana essential oil for use as a food preservative." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=12132.
Full textAbstract:
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgicoIn this study, the Eucalyptus staigeriana essential oil (ESO) was nanoencapsulated and determined the bactericidal effect of its active principle against two strains of pathogenic mircrorganisms, as a preliminary study for use in food preservation. The process occurred by forming a nanoemulsion and spray-drying, using the cashew gum (CG) as encapsulating material. The nanoparticles were characterized by analysis of particle size distribution, zeta potential, absorption spectroscopy in the infrared Fourier transform spectroscopy (FTIR), thermal analysis (TGA/DSC), in vitro release kinetics, gas chromatography coupled to mass spectrometry (GC-MS) and stability of the encapsulated. Was also determined the Minimum Bactericidal Concentration (MBC) of nanoparticles, essential oil, and cashew gum to evaluate its antimicrobial activity against Listeria monocytogenes ATCC 19115 (Gram-positive) and Salmonella Enteritidis IAL 1132 (Gram-negative). The nanoparticles had size ranging from 27.70 Â 3.42 nm to 432.67 Â 41.47 nm in accordance with the formulation, and negatively charged surface. The presence of ESO in the nanoparticles is observed through changes in peak resolutions of the spectra obtained by FT-IR. Thermal analysis showed the main events of mass loss of the samples associated with the degradation of CG. The content of ESO nanoencapsulated varied between 4.76% and 7.12%. The increase in the proportion of CG favored the rapid release of oil in water due to the increased hydrophilic character, and enhance the ability of the nanoparticles to retain the ESO in the polymeric shell during the 365 days. The results for MBC indicated a bactericidal action of the nanoencapsulated oil, and pure oil more efficient in Gram-positive. However, the nanoparticles showed better results against Gram-negative bacteria, due to a possible synergistic effect between the CG and ESO.
Neste trabalho, o Ãleo essencial de Eucalyptus staigeriana (OES) foi nanoencapsulado e determinado o efeito bactericida de seu princÃpio ativo contra duas cepas de mircrorganismos patogÃnicos, como um estudo preliminar para utilizaÃÃo na conservaÃÃo de alimentos. O processo ocorreu atravÃs da formaÃÃo de uma nanoemulsÃo e secagem em spray-drying utilizando a goma de cajueiro (GC) como material encapsulante. As nanopartÃculas foram caracterizadas atravÃs das anÃlises de tamanho e distribuiÃÃo de partÃcula, potencial zeta, espectroscopia de absorÃÃo na regiÃo do infravermelho com transformada de Fourier (FTIR), anÃlise tÃrmica (TGA/DSC), cinÃtica de liberaÃÃo in vitro, cromatografia gasosa acoplada à espectrometria de massa (CG-EM) e estabilidade do encapsulado. Foi tambÃm determinada a ConcentraÃÃo Bactericida MÃnima (CBM) das nanopartÃculas, do Ãleo essencial e da goma de cajueiro para avaliar sua aÃÃo antimicrobiana contra Listeria monocytogenes ATCC 19115 (Gram-positiva) e Salmonella Enteritidis IAL 1132 (Gram-negativa). As nanopartÃculas apresentaram tamanho que variaram de 27,70  3,42 nm a 432,67  41,47 nm, de acordo com a formulaÃÃo, e a superfÃcie carregada negativamente. A presenÃa do OES nas nanopartÃculas à observada atravÃs de modificaÃÃes nas resoluÃÃes de pico dos espectros obtidos por FTIR. A anÃlise tÃrmica evidenciou os principais eventos de perda de massa das amostras associados à degradaÃÃo de GC. O teor de OES nanoencapsulado variou entre 4,76 % e 7,12 %. O aumento na proporÃÃo de GC favoreceu a uma rÃpida liberaÃÃo do Ãleo em Ãgua devido ao aumento do carÃter hidrofÃlico, alÃm de aumentar a capacidade das nanopartÃculas em reter o OES no invÃlucro polimÃrico no decorrer dos 365 dias. Os resultados para CBM indicaram uma aÃÃo bactericida do Ãleo nanoencapsulado e do Ãleo puro mais eficiente na bactÃria Gram-positiva. No entanto, as nanopartÃculas mostraram um resultado melhor contra a bactÃria Gram-negativa, devido a um possÃvel efeito sinÃrgico entre a GC e o OES.
33
Rhoades, Jonathan. "The antimicrobial activity of chitosan and its application as a food preservative." Thesis, London South Bank University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288171.
Full text
34
Mollapour, Mehdi. "Molecular genetic analysis of preservative resistance in Zygosaccharomyces bailii." Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369230.
Full text
35
Ferreira, Maria Adelia Silva Santos. "The effect of preservative factors on survival/growth of the food-borne pathogen Listeria monocytogenes." Thesis, University of East Anglia, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316199.
Full text
36
Peterson, Hilary. "The effect of cocoa powder on the development of oxidative rancidity in peanut products." Thesis, Kansas State University, 2013. http://hdl.handle.net/2097/16229.
Full textAbstract:
Master of ScienceFood Science
J. Scott Smith
The objective of this study was to observe the effect of natural cocoa powder versus 200 ppm of tocopherols on delaying the onset of oxidative rancidity in peanuts, peanut butter, and peanut oil. The samples were obtained from a single lot of blended Runner peanuts after roasting, grinding, and pressing. The samples were treated within a week of initial roasting with either 200 ppm of mixed tocopherols or 2.5% cocoa powder. The development of oxidation was monitored by peroxide value (PV) and gas chromatography monitoring of hexanal development. The peanut butter samples were assessed by a professional sensory panel using descriptive analysis for the development of rancidity. The data was analyzed using JMP SAS software. In peanuts, the cocoa powder sample developed significantly lower levels of oxidation identifiers than the tocopherol or control samples. In peanut oil, there was no significant difference in levels of oxidation identifiers between the treatments. In peanut butter, the PV was significantly higher in the tocopherol sample than the cocoa powder or control samples, but no significant difference was observed in hexanal. The results of the sensory analysis indicated that the cocoa powder depressed the perception of both positive and negative attributes compared to the tocopherol and control samples. This study showed that cocoa powder may be a more effective preservative than an untreated sample or a sample treated with 200 ppm of tocopherols in peanuts and peanut butter; however, cocoa powder at 2.5% w/w basis did not perform as a significant antioxidant in peanut oil.
37
Biplab, Rajbanshi. "Investigation of host- guest inclusion complexation of some biologically potent molecules and solvent consequences of some food preservations with the manifestation of synthesis, characterization and innovative applications." Thesis, University of North Bengal, 2020. http://ir.nbu.ac.in/handle/123456789/3963.
Full text
38
Hsu, James Chun Hou Chemical Sciences & Engineering Faculty of Engineering UNSW. "Nitrate, nitrite and nitrosamine: contents and analyses in selected foods; effect of vitamin C supplementation on N-nitrosodimethylamine formation in humans; and an investigation of natural alternatives to nitrites as preservatives in cured meat products." Awarded By:University of New South Wales. Chemical Sciences & Engineering, 2009. http://handle.unsw.edu.au/1959.4/43740.
Full textAbstract:
Dietary nitrite intake has been implicated in numerous gastrointestinal cancers in humans due to the formation of a group of carcinogens called N-nitroso compounds. The need to estimate their intake is vital in establishing at risk population and to monitor and perhaps one day manage their dietary intake. This is the first study to estimate nitrate and nitrite in selected vegetables, cured and fresh meat in Australian food supply using ion-paired reversed-phased HPLC. Nitrite content in meat products analysed ranged from 0 to 83.9 mg/kg in medallion beef and Frankfurt, respectively; nitrate content ranged from 18.7 mg/kg in minced beef to 142.5 mg/kg in salami. The nitrite content was below the maximum limit set by the Food Standards Australia and New Zealand. Nitrate content in selected vegetables ranged from 123 to 4850 mg/kg in Iceberg lettuce and English spinach, respectively; only minimal nitrite at 20 mg/kg was present in Gai choy, which was most likely due to bacterial contamination during storage. Based on the food consumption pattern of Australians, the dietary nitrite and nitrate intake from bacon were 1.51 and 3.42 mg per capita per day, which was below the Adequate Daily Intake set by the European Union Scientific Committee for food in 1995. Taking into considerations of oral nitrate reduction to nitrite and the endogenous nitrate formation, the upper extreme of dietary nitrite and nitrate intake in Australians were 44 and 2.4 times over the ADI, respectively. However, this does not take into effect of other dietary promoters and inhibitors. Eighteen healthy human volunteers were put on a low nitrate, nitrite and antioxidant diet for three days during which they were fed one serving of cured meat with and without 500 mg of vitamin C. Using GC-MS, N-nitrosodimethylamine was not detected in the urine before or after vitamin C supplementation, suggested that a diet low on nitrate and nitrite cannot produce NDMA and thus may reduce the risk of developing gastrointestinal cancers. Different extraction methods and combination of herbs and spices were demonstrated in vitro to show inhibition against B. cereus, Escherichia coli, Listeria monocytogenes, Salmonella Enteritidis and Staphylococcus aureus. In addition, autoclaved turmeric powder at 0.3 % (w/v), hot water extracted turmeric with ginger at 0.5 % and rosemary at 1.0 % showed growth inhibition against Clostridium sporogenes, which was used as a surrogate for Clostridium botulinum. The use of these combinations of herbs and spices may replace or at least reduce the use of nitrite as a preservative in cured meat products to prevent botulism and reduce dietary nitrite intake.
39
Benito, Clemente Doris Liliana, and Quispe Edith Roxana Cabezas. "Nivel de autoestima y uso de preservativo en madres jóvenes, Instituto Nacional Materno Perinatal, enero 2012." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2012. https://hdl.handle.net/20.500.12672/15888.
Full textAbstract:
Publicación a texto completo no autorizada por el autorDa a conocer si existe relación entre el nivel de autoestima y el uso de preservativo evaluado por madres jóvenes atendidas en el Instituto Nacional Materno Perinatal durante un mes del año 2012. El estudio es descriptivo, correlacionar, transversal; compuesto por 183 madres jóvenes cuyas edades comprenden de 20 -28 años, atendidas en el Instituto Nacional Materno Perinatal (INMP) en enero del 2012; que use o no preservativo en sus relaciones sexuales evaluado en su pareja. El método empleado fue encuesta, técnica entrevista mediante el instrumento cuestionario. Siguiendo los criterios de inclusión y exclusión se procedió a la recolección de datos, posteriormente fueron tabuladas en tablas y gráficos del programa SPPS 17. Se utilizó la estadística descriptiva, así mismo análisis bivariado como Chi cuadrado. De la población en estudio, el 66.1% se encuentra en unión libre, el grado de instrucción predominante fue la de secundaria completa con un 57.9%, la religión católica predominó con un 69.4% de las encuestadas, siendo el 40.4% poco religiosas. Referente a los hábitos nocivos no se halló ningún caso de consumos de algún tipo de drogas más si de 77% que refirió consumir alcohol en poca frecuencia. En sentido general se halló que un 50% de encuestadas, tiene el nivel de autoestima media, 24.5% presenta un nivel bajo de autoestima. Se encontró que existe relación directa entre autoestima y el uso de preservativo masculino; y en el caso de madres jóvenes que presentan baja autoestima el 50% no lo usa en sus relaciones sexuales. (x2= 22.575, p0.5). Otro de los resultados fue la relación entre uso de preservativo y conocimientos, siendo esta significativa (x2=18.763, (p= 0,005) a pesar de ello presentan un menor uso del preservativo masculino en sus relaciones sexuales. Con respecto a la actitud sobre el uso del preservativo masculino solo un 26,8% tiene una actitud favorable. Se obtiene también, que el 51,9% está de acuerdo en no solicitar a su pareja el uso del preservativo al tener una pareja estable. Se concluye que en la población se estimó el nivel de autoestima, indicando que el 50% de las mujeres presenta una autoestima media, un 24,5% una autoestima baja. Por otro lado, se concluye que; el conocimiento referente al uso del preservativo en la mitad de nuestra muestra lo ocupa el término medio, teniendo la cuarta parte de la muestra un conocimiento alto, y un conocimiento bajo una cuarta parte de la muestra. Al relacionar el conocimiento y el uso del preservativo masculino, se concluye que existe una relación positiva de acuerdo a los resultados de las pruebas estadísticas. Con respecto a la actitud sobre el uso del preservativo masculino solo un 26,8% tiene una actitud favorable. En el caso de las prácticas del uso del preservativo masculino, un 51,4% presenta un nivel bajo, seguido de un 25,1% con un nivel medio. Otro hallazgo fue que un 50% de las que tienen baja autoestima, el 35% de las que presentan una autoestima media y el 11% de las que presentan una alta autoestima no usan preservativo masculino.
40
Nunes, Tatiana Pacheco. "Efeito da pré-cura na estabilidade microbiológica de carne mecanicamente separada e elaboração de um produto reestruturado com filés de peito de galinhas de descarte." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/11/11141/tde-20102003-161041/.
Full textAbstract:
Os peitos de galinhas matrizes pesadas de corte, poedeiras comerciais brancas e frangos foram desossados manualmente, com o objetivo de avaliar e comparar as propriedades tecnológicas capacidade de retenção de água e de emulsificação bem como pH e composição centesimal, além de elaborar e avaliar sensorialmente um produto reestruturado empanado, tipo nugget. Os resultados das análises indicaram que não houve diferença significativa entre as carnes analisadas, nem entre produtos processados, implicando utilização regular desse tipo de matéria-prima na indústria de alimentos. O restante das carcaças das galinhas foi utilizado para extração de carne mecanicamente separada (CMS) para avaliação da estabilidade microbiológica. As CMSs foram submetidas a dois tratamentos: I) com 150ppm de nitrito, embaladas em saco de polietileno; e II) com 150ppm de nitrito e 500ppm de eritorbato, embaladas em saco de polietileno. Como controle, as amostras de CMS foram apenas acondicionadas em sacos de polietileno. Todas as embalagens foram estocadas e congeladas a 18ºC por 99 dias. Os resultados da análise de caracterização microbiológica indicaram que tanto as amostras de CMS de galinha matriz quanto de galinha poedeira atenderam os padrões de contagem requeridos pela legislação Brasileira. A avaliação da estabilidade microbiológica das CMSs no primeiro e no último dia para mesófilos, Escherichia coli, Staphylococcus aureus, Clostridium perfringens e Pseudomonas, bem como as análises quinzenais de microrganismos psicrotróficos, indicaram que não houve uma redução significativa nas contagens, independentemente do tratamento aplicado. Não foi detectada Salmonella em nenhuma das amostras analisadas. Tais resultados apontaram o tempo de estocagem como o principal fator na redução da carga bacteriana.The breasts of heavy fowls, white commercial egg-layers and chickens were manually deboned in order to evaluate and compare technological propertieswater hold and emulsifying capacityand pH and centesimal composition, as well as to prepare and assess a restructured coated product. The results of the analyses indicated that there was not a significant difference between the meats analyzed, nor among the processed products, implying the regular use of such meat in the food industry. The remaining parts of the hens carcasses were mechanically deboned for the evaluation of microbiological stability. The mechanically deboned meat (MDM) was submitted to two treatments: I) 150ppm of nitrite, packed in polyethylene bags; II) 150ppm of nitrite and 500ppm of erythorbate, packed in polyethylene bags. The control meats were just packed in polyethylene bags. All samples were frozen-stored at 18ºC for 99 days. The results of microbiological characterization indicated that both samples from heavy fowls and egg-layers were in accordance with the Brazilian legislation. MDM microbiological stability evaluation on the first and last days for fecal coliforms, mesophiles, Staphylococcus aureus, Clostridium perfringens and Pseudomonas, as well as the analyses carried out every fifteen days for psychrotrophics bacteria indicated that there was not a significant reduction in the presence of the above, irrespective of the treatment applied. Salmonella was not detected in any of the samples. Such results indicated that freezing storage period was the main factor responsible for the reduction of the bacterial count in MDM.
41
Arauz, Luciana Juncioni de. "Produção de nisina em leite desnatado diluído por Lactococcus lactis subsp. lactis ATCC 11454 em biorreator." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/9/9134/tde-05082011-171618/.
Full textAbstract:
Nisina é um peptídeo antimicrobiano natural produzido por Lactococcus lactis subsp. lactis ATCC 11454 durante a fase exponencial de crescimento. A bacteriocina é usada como conservante natural de alimentos, uma vez que mostra atividade antimicrobiana contra bactérias Gram-positivas e esporos. Tem potencial aplicação em inúmeros campos (farmacêutico, veterinário e cosméticos). O objetivo deste trabalho foi estudar a cinética de crescimento bacteriano e a produção de nisina em biorreator, utilizando leite desnatado diluído, como um meio de cultura a baixo custo. Também foram avaliados os consumos de açúcar e proteína, formação de ácido lático e adsorção de nisina nas células produtoras durante os processos de produção de nisina. Pré-cultivos com 107 UFC.mL-1 de Lactococcus lactis foram cultivados em biorreator de 2 L contendo 25% de leite desnatado diluído em água (1,5 L, pH 6,7). Os ensaios foram esenvolvidos a 30°C por 52 horas, variando a agitação e aeração: (i) 200 rpm (0,0, 0,5, 1,0 e 2,0 L.min-1) e (ii) 100 rpm (0,0 e 0,5 L.min-1). A atividade de nisina foi avaliada pelo método de difusão em ágar, utilizando Lactobacillus sakei ATCC 15521 como microrganismo sensível à ação de nisina. A melhor concentração de nisina (62,68 mg.L-1 ou 2511,89 AU.mL-1), foi obtida em 16 horas, 200 rpm e sem aeração (kLa = 5,29 x 10-3 h-1). A adsorção de nisina nas células produtoras foram baixas (6,8 - 15,1%), quando comparadas com a atividade do sobrenadante. Estes resultados mostraram que o meio de cultivo composto por leite desnatado diluído favoreceu o crescimento celular e produção associada ao crescimento da nisina. Foram realizados estudos preliminares de liofilização (bioconservação) e purificação por cromatografia da nisina produzida em biorreator. A liofilização apresentou perda da atividade de nisina (24,8%), enquanto a purificação por cromatografia de interação hidrofóbica com resina Butyl-Sepharose, recuperou 40% da atividade da biomolécula, mostrando que ambos os processos poderão ser aplicados à bacteriocina.Nisin is a natural antimicrobial peptide produced by Lactococcus lactis subsp. lactis ATCC 11454 during its exponential growth phase. The bacteriocin is used as natural food preservative due to its antimicrobial activity against Gram-positive bacteria and outgrowth of spores. This property allows its application in numerous fields (pharmaceutical, veterinary and cosmetic). The aim of this work was to study the bacterial growth kinetics of L. lactis and respective nisin production in bioreactor, using diluted skimmed milk as an inexpensive medium. During the production, the consumption of sugar and protein, lactic acid formation and nisin adsorption on the producer strain cells were evaluated. Pre-cultivation with 107 UFC.mL-1 of L. lactis were expanded in a 2 L bioreactor containing 25% diluted skimmed milk in water (1.5 L, pH 6.7). The assays were performed at 30°C for 52 hours, varying agitation and airflow rate: (i) 200 rpm (0.0, 0.5, 1.0 and 2.0 L.min-1) and (ii) 100 rpm (0.0, 0.5 L.min-1). Nisin activity was evaluated through diffusion assays using Lactobacillus sakei ATCC 15521 as sensitive strain. The best nisin concentration (62.68 mg.L-1 or 2511.89 AU.mL-1), was achieved at 16 hours, 200 rpm and with no airflow rate (kLa = 5.29 x 10-3 h-1). The quantity of nisin adsorbed by the producer cells were low (6.8 -15.1%) when compared to the quantity released in the supernatant. These results showed that diluted skimmed milk supported cell growth and growth-associated nisin. Preliminary assays of lyophilization (biopreservation) and purification by chromatography of nisin produced in bioreactor were performed. Lyophilization presented a loss of nisin activity (24.8%) while purification by hydrophobic interaction chromatography with Butyl-Sepharose column recovered 40% of the activity, showing that both processes can be applied to the bacteriocin.
42
Yeh, Miao-Tseng, and 葉妙禎. "Deternimation of Food Preservatives by Capillary Electrophoresis." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/75840466969303001964.
Full textAbstract:
碩士國立宜蘭大學
食品科學系碩士班
97
Chemical preservatives are commonly used in food products to prevent alteration and degradation by microorganisms during storage. However, excessive addition of these preservatives may be harmful to consumers. Therefore, the development of simple and rapid analysis methods of these preservatives is of great importance for food safety. The common analytical methods for preservatives in the food products are thin-layer chromatography, spectrophotometric method, gas chromatography, high performance liquid chromatography and capillary electrophoresis. Because of the advantages like the high separation efficiency, the short analysis time, the few sample volume needed, the simplicity of method development, the variety of application mode, and the complete instrumental automation etc... Therefore, capillary electrophoresis has become the important analysis method outside high performance liquid chromatography for preservatives. This research establishes a capillary zone electrophoresis method with direct and indirect detection to simultaneously determine eight common used preservatives: acetic acid, benzoic acid, boric acid, dehydration acetic acid, methyl 4-hydroxybenzoate, propionic acid, sorbic acid and sulfite in food samples is performed by capillary zone electrophoresis with 0.5mM cetyltrimethyl-ammonium bromide (CTAB)－10mM 2,6-pyridinedicarboxylic acid (PDC) as background electrolyte at pH 10.8 and 25oC. The choices of the background electrolytes and the applied voltage were optimized. The effects of CTAB and pH on the separation were investigated in detail. Under the optimum condition, the linearity, reproducibility and detection limit of eight preservatives are shown, respectively. As an application of the method proposed, various samples of soft drink, vinegar, pearl sago, bread and dried Day Lily are analyzed to determine preservatives. The procedure described provides the advantages of good selectivity, recovery, rapid speed and simplicity for the separation and determination of preservatives.
43
Yang, Shih-Cheng, and 楊仕丞. "Assessing the Health Risk for Food Preservatives in Taiwanese Population." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/qqbm63.
Full text
44
Huang, Li-Feng, and 黃莉芬. "Investigation of preservatives for food sold in central Taiwan (2015-2017)." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/93sg95.
Full textAbstract:
碩士國立中興大學
食品暨應用生物科技學系所
106
This study is based on the central regional joint division of labor to test the market for food preservatives. The statistical survey collected 6,518 samples from Taichung City, Nantou County and Changhua County from January 2015 to December 2017, according to the Ministry of Health and Welfare. The method of testing preservatives in foods is tested against 12 of the food additives approved by the regulations. Among the 6,518 specimens, 6,384 were qualified and the pass rate was 98%. The lower qualified rate was followed by the qualified rate of wet rice products in 2015 of 91.3%; the pass rate of pickles and pickled vegetables in 2016 was 91.2%; the pass rate of wet products in 2017 was 94.4%. The unprepared preservatives detected by the specimens were most common with benzoic acid (72%) and hexadienoic acid (23%). In 2015, 100 pieces of preservatives in the lunch inspection of the school were all qualified; in 2016, the pass rate of 167 pieces was 99.4%; in 2017, the pass rate of 291 pieces was 99%, and the general condition of the school foods that were safe and safe was still unsatisfactory. . The traditional annual food project sampling test showed that the unqualified rate ranged from 9.7% to full qualification. It is recommended that the education counselors should be continued and the sampling audit should be maintained to monitor the safety of food ingredients in the market. The results of this study indicate that food items that are not qualified for common preservatives should continue to be strengthened. For eligible products for several consecutive years, resources may be recommended. Commonly used preservatives should be used to guide the correct use of preservatives from the source of the additives, in order to reduce the misuse of misuse.
45
Cheung, Kuen. "Evaluation of commercial practices to enhance the shelf-life of cottage cheese." Thesis, 1993. http://hdl.handle.net/1957/35626.
Full text
46
Chang, Tsung-Sheng, and 張琮昇. "Food safety risk assessment about preservatives in vegan and non-vegan population." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/8sy2gw.
Full text
47
LIAO-RIH-CI and 廖日祺. "The development of an analytical method for preservatives contained in cosmetic and food samples." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/35209499744810173860.
Full textAbstract:
碩士正修科技大學
化工與材料工程研究所
102
High Performance Liquid Chromatography with ultraviolet detector (HPLC-UV) was used as analytical tool to analyze 10 preservatives commonly used in cosmetics and food samples. Ten preservatives are salicylic acid, benzoic acid, sorbic acid, phenoxyethanol, methyl paraben, ethyl paraben, isopropyl paraben, propyl paraben, isobutyl paraben, and butyl paraben, which were listed by retention time respectively. Muddy and diluted liquid samples in this research were extracted by 70％ methanol and then filtered. Finally, all analytes were quantitatively analyzed with HPLC-UV on a Luna C18(2) 250 × 4.6 mm 5 μm column. The whole chromatographic processes could he completed in 30 minutes by using gradient elution with methanol form 10 to 65％ and 5 mM ammonium acetate at pH =4.5. The mobile phase flow rate was 1mL/min and detection wavelengths were at 240 and 265 nm, which all 10 preservatives can be analyzed simultaneously. All results showed calibration curve has regression coefficient from 0.9999 to 1.0000, the recoveries of all samples for cosmetics were from 71.5 to 108%, and recoveries of all samples for food were from 76.9 to 108%. Among all testing samples, one cosmetic and three food samples were over the legal regulation.
48
Jamuna, M. "Studies on the efficacy of bacteriocins from Lactic acid bacteria as food preservatives and their applicability in non-fermented foods." Thesis, 2004. http://hdl.handle.net/2009/3009.
Full text
49
Yun, Yu Chih, and 游芷筠. "Effects of Different Preservatives and Food Gums on the Quality and Preservation of Tapioca Starch Pearl." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/54147432330164640131.
Full textAbstract:
碩士大葉大學
生物產業科技學系
94
The first part of this study is to discuss the effect of combination of different preservatives and pH values on the quality and preservation of tapioca pearls. Their color and luster were found to be sparkling and crystal-clear when the pH value of pearls was adjusted to 4, and the quality is better, too. Even not preservatives added, when pH is 4, tapioca pearls can be stored for two more days than those not pH adjusting. Among three kinds of preservatives, tapioca pearls with potassium sorbate added was found to have better quality, sensory evaluation analysis, and store life. The second part of this study is to investigate the effects of different nature antimicrobial agents on the preservation and quality influence of tapioca pearls. Adding nature antimicrobial agents can promote the quality of tapioca pearls. Tapioca pearls with Trehalose added was found to have better antimicrobial ability during storage. It had lower total aerobic count and better quality after forty-fifth day’s storage. The third part of this study was to investigate the influence on the quality of tapioca pearls of different pH value adjusted. The result shows that the most suitable pH is 4, and when adjusts pH was adjusted to 3.5, the quality of tapioca pearls become bad. The fourth and fifth parts of this study was to investigate different kinds and proportion of gums added on the quality of tapioca pearls when their pH is adjusted to 3.5. When single gum was added, tapioca pearls with 2 g Xanthan gum added have better sensory evaluation analysis and quality. With complex gums was added in tapioca pearls, 2 g Xanthan gum and 2 g Guar gum mixture was found to have better sensory evaluation analysis and quality. The sixth part of this study found that 4 g CMC and 2 g Xanthan gum added in 1 Kg tapioca starch was the best formulation to make good quality pearls.
50
Jay, Chang-Chy, and 張志杰. "A Study on the Simultaneous Determination of Twelve Food Preservatives by Gas Chromatograph - Flame Ionization Detector." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/74690826112824161663.
Full textAbstract:
碩士國立屏東科技大學
食品科學系所
95
At present, most methods for determining food preservatives are based on the testing methods of Chinese National Standards （CNS 10949-N6190）. The methods require collecting the distillate by dissolving with pure water or solvent or by steam distillation, to extract the distillate repeatedly with ether at different PH values through multiple complicated processes and then the concentrate must be analyzed by Gas Chromatograph-Flame Ionization Detector （GC-FID）. The above-mentioned methods could be applied when the sample number is small. However, the quantity of vitrics, consumptive materials, manpower, equipment, and operation time would be multiplied when performing analyses on a great variety of food samples. The greater the number of operation processes, the greater the likelihood that system and human errors will increase. Limited by extracting processes and instrument detection conditions, the following five acids and six esters could only be determined one by one: Sorbic Acid, Dehydroacetic Acid, Benzoic Acid, Salicylic acid, p-Hydroxybenzoic acid, Methyl -p-hydroxybenzoate, Ethyl p-Hydroxybenzoate, Propyl -p-Hydroxybenzoate, Butyl p-Hydroxybenzoate, Isopropyl -p-Hydroxybenzoate and Isobutyl p-Hydroxybenzoate. To enhance the recovery rate and sensitivity of the test, the Steam Distillation Method was chosen from among the traditional methods to avoid the various potential interferences, such as food’s ingredients, structure, composition, additives, etc. Ether was also chosen for proceeding with the extraction and concentration, due to its higher solubility in relation to the target substances. The new operation processes of test and analytic condition of instrument were established by combining GC-FID and DB-5（J&W）. The system and human errors could be avoided by simplifying and streamlining the pretreatment process of the test. This method could be applied for determining twelve statutory food additive preservatives under the same conditions （Sorbic Acid, Dehydroacetic Acid, Benzoic Acid, Salicylic acid, p-Hydroxybenzoic acid, Methyl p-hydroxybenzoate, Ethyl p-Hydroxybenzoate, Propyl p-Hydroxybenzoate, Butyl p-Hydroxybenzoate, Isopropyl p-Hydroxybenzoate, Isobutyl p-Hydroxybenzoate and Biphenyl.）