Dissertations / Theses on the topic 'Emulsifying properties'

Previous studies on the use of nonfat dry milk, whey protein concentrate 34 and lactose powders in processed cheeses or cheese analogs found that increasing the percentage of lactose was associated with an increase in browning and crystallization. There has been little work done of the effects of lactose in processed cheese functionality. Therefore, the objective of this research is to build on and understand the effects of lactose from by three commercially produced dairy powders (nonfat dry milk (NFDM), whey protein concentrate 34 (WPC), lactose) and two different emulsifying salts on properties of processed cheese. Processed cheeses were made using either trisodium citrate or disodium phosphate dihydrate emulsifiers and standardized to lactose levels of 4 or 8 percent by weight. Processed cheeses were made with natural cheese aged at 4oC for 30, 60, 90, and 120 days of age. For each age of natural cheese, processed cheeses were made in triplicates for each treatment. A small batch (5 lb) Stephan single blade cooker in a pilot plant setting was used to conduct the experiments. The cheeses were tested within a week of manufacture for moisture by microwave method, pH, melt by Arnott melt test, hardness and cohesiveness by texture profile analysis, and browning by ImageJ software. The pH of the cheeses showed that there was a significant difference (

Im Rahmen der vorliegenden Arbeit wurde der Einfluss der nichtenzymatischen Glykosylierung auf das Denaturierungsverhalten und die funktionellen Eigenschaften von Molkenproteinen, hier im speziellen die emulgierenden Eigenschaften, untersucht. Nach einer Bestimmung technologisch relevante Glykosylierungsgrade sollten in unterschiedlich glykosylierten Molkenproteinpräparaten das Denaturierungsverhalten sowie die Emulgiereigenschaften in Abhängigkeit vom Glykosylierungsgrad mit unterschiedlichen Methoden bestimmt werden. Der aus praktischer Sicht relevante Einfluss der Glykosylierung auf die sensorischen Eigenschaften wurde einerseits in Molkenproteinlösungen und andererseits in einem komplexen System (Modell-Schmelzkäsezubereitung) erfasst. Schließlich galt es, den Einfluss der Glykosylierung auf die Mikrostruktur und die Festigkeit am Beispiel der Modell- Schmelzkäsezubereitung zu untersuchen und daraus unmittelbare Konsequenzen für die technologische Praxis abzuleiten.

Le concept de Raffinerie de microalgues consiste à mettre au point des méthodes extrapolables à l’échelle industrielle permettant d’extraire, de séparer et de valoriser l’ensemble du contenu intracellulaire des microalgues. La mise en oeuvre d’un tel concept nécessite d’avoir des données sur la composition, sur la possibilité de séparation, et sur les fonctionnalités des différentes fractions de la biomasse. Dans le cadre de ce travail, Haematococcus pluvialis, qui produit un pigment à forte valeur ajoutée (l’astaxanthine) mais pour laquelle peu d’information n’est disponible sur les autres composés de sa biomasse, a été choisie comme modèle de microalgue. L’objectif est de quantifier et d’étudier la possibilité de valorisation des différentes fractions de la biomasse à différents stades de culture. Après une étape de lyse cellulaire par broyage haute pression, plusieurs fractions sont obtenues. Les protéines présentes dans le surnageant de broyage ont fait l’objet d’une caractérisation en terme de répartition des masses molaires et plusieurs méthodes de purification / concentration ont été mises en oeuvre. Les propriétés émulsifiantes (capacité émulsifiante, stabilité d’émulsion et index d’activité émulsifiante) ont été déterminées et comparées à celles d’un ingrédient commercial (caséinate de sodium). Cette étude a permis de montrer que les protéinesd’H. pluvialis possèdent un fort potentiel en tant qu’agent émulsifiant. Le surnageant de broyage, en plus des protéines, contient également des sucres, et une quantité importante de lipides et de pigments. Afin de séparer les composés hydrosolubles de ceux liposolubles dans le surnageant, une méthode basée sur l’utilisation du polyethyleneimine (PEI) a été mise en oeuvre. Ainsi il a été possible de définir des conditions permettant la floculation de 96 % des lipides et pigments en conservant 100 % des sucres et 89 % des protéines dans la phase aqueuse. Dans la suite du travail, la chromatographie de partage centrifuge (CPC) a été testée afin de séparer les lipides et les pigments. L’utilisation d’un système heptane : méthanol (+ 2 % eau) a ainsi montré que cette méthode permet le fractionnement des composés liposolubles, principal verrou technologique de la bioraffinerie d’H. pluvialis. Un schéma intégré de bioraffinage d’Haematococcus pluvialis a ainsi pu être proposé
The concept of Refinery of microalgae consists in finding experimental procedure allowing the separation / valorization of the intracellular components of microalgae with the aim of the scale-up at industrial level. However the implementation of such a concept requires the acquisition of data on the composition, component separation efficiencies, and their valorization ability. For this study, Haematococcus pluvialis, a known producer of a high value-added pigment (astaxanthin) was chosen as a model of microalgae. If the characteristic of the pigment of this microalga is indeed well defined, there is still a lack of knowledge on the other compounds of its biomass. The aim of this work is to quantify and to study the valorization potential of various fractions of the biomass at different stages of the culture. After quantification and characterization of the various fractions of the biomass, cell lysis was achieved to obtain supernatant that contains beside pigment, proteins, sugars and important quantity of lipids. Proteins in the supernatant were characterized in term of molecular masses distribution. Several methods based on combined effect of high pressure disruption / pH shifting and ultrafiltration were implemented for concentration/fractionation of protein matrix. The emulsifying properties (emulsifying capacity and stability) were determined and compared to those of a commercial ingredient (sodium caseinate). It has been shown that the proteins from H. pluvialis possess a high potential as emulsifying agent. Using polyethyleneimine (PEI) an experimental procedure was tested to separate the hydrosoluble and liposoluble compounds from the supernatant. Thanks to this procedure, it was then possible to define experimental conditions permitting the flocculation of 96 % of lipids and pigments while 100 % of sugars and 89 % of proteins remained in the aqueous phase. Afterward, the centrifugal partition chromatography (CPC) was tested to separate lipids and pigments. The use of a heptane : méthanol (+ 2 % water) system highlighted that this method induced the separation of the liposoluble compounds, the main technological deadlock in the biorefinery of H. pluvialis. Finally, an integrated flow-sheet for Haematococcus pluvialis biorefinery has been advised

Les protéines végétales sont une option cohérente pour nourrir la planète tout en limitant le réchauffement climatique. Les protéines courantes (blé, soja et maïs) ne seront bientôt plus suffisantes pour répondre à l’augmentation de la demande en protéines. Cette thèse porte sur la valorisation d’une nouvelle source de protéine végétale pour l’alimentation humaine, à partir d’un coproduit de l’huilerie : les protéines de chanvre issues de tourteau de presse. Pour répondre à cet objectif les trois axes suivis sont : la définition des conditions d’extraction, l’étude des propriétés physicochimiques des isolats extraits selon les conditions définies et l’étude de leurs propriétés émulsifiantes. Les données de la littérature relatives à l’extraction des protéines de chanvre sont peu nombreuses et peu détaillées. Les protéines y sont généralement extraites à partir de tourteau délipidé au solvant, par solubilisation alcaline (pH 10), précipitation isoélectrique (pH 5), neutralisation (pH 7) et lyophilisation. Ces isolats protéiques semblent posséder de faibles solubilités sur une large gamme de pH, probablement à cause de fortes interactions entre les protéines au point isoélectrique qui en insolubilise une partie. L’extraction souhaitée dans notre étude est une extraction à partir de tourteau brut (sans solvant), sans précipitation isoélectrique et permettant d’extraire simultanément les globulines et les albumines. L’impact de conditions d’extraction sur la qualité et la quantité de protéines extraites est déterminé. Les conditions d’hydratation étudiées sont différents pH (2 à 12), forces ioniques (0 à 500 mM de NaCl) et ratios massiques tourteau/eau (2 à 22%). Les impacts d’une étape de purification par ultrafiltration et du mode de séchage (atomisation ou lyophilisation) sont également étudiés. Seuls des pH alcalins ≥10 permettent l’extraction simultanée des globulines et des albumines avec des rendements ≥40%. En revanche de tels pH solubilisent également des composés phénoliques qui peuvent se complexer aux protéines. Une étape de diafiltration par ultrafiltration est nécessaire pour augmenter la pureté protéique à plus de 80% et l’atomisation ne semble pas dénaturante. L’extraction à pH 10 permet d’obtenir des protéines natives. A l’état brut elles montrent de bonnes aptitudes émulsifiantes. Une dénaturation thermique réduit fortement leurs propriétés émulsifiantes. L’extraction à pH 12 dénature les protéines certainement suite à une charge de surface élevée qui induit leur dépliement. Des agrégats impliquant probablement des phénols via des liaisons covalentes sont formés. Cependant la solubilité de ces protéines de même que leurs propriétés émulsifiantes sont meilleures que celles des protéines extraites à pH 10. A travers ce manuscrit nous discutions et tentons de comprendre les différences observées entre les protéines extraites à pH 10 et à pH 12
Plant proteins are a coherent option to feed the planet while limiting global warming. Common proteins (wheat, soya and maize) will soon no longer be sufficient to meet the increased demand for proteins. This thesis focuses on the development of a new source of plant protein for human consumption, based on a co-product of the oil mill: hemp proteins from press-cake. To meet this objective, the three main lines of action are: the definition of extraction conditions, the study of the physico-chemical properties of the isolates extracted under the defined conditions and the study of their emulsifying properties. The data in the literature on the extraction of hemp proteins are limited and not very detailed. Proteins are generally extracted from solvent-delipidated press-cake by alkaline solubilization (pH 10), isoelectric precipitation (pH 5), neutralization (pH 7) and freeze-drying. These protein isolates appear to have low solubilities over a wide pH range, probably due to strong interactions between proteins at the isoelectric point that insolubilize some of them. The extraction desired in our study is an extraction from raw press-cake (without solvent), without isoelectric precipitation and allowing globulins and albumins to be extracted simultaneously. The impact of extraction conditions on the quality and quantity of extracted proteins is determined. The hydration conditions studied are different pH (2 to 12), ionic strengths (0 to 500 mM NaCl) and weight ratios of press-cake/water (2 to 22%). The effects of an ultrafiltration purification step and the drying method (spray or freeze-drying) are also studied. Only alkaline pH ≥10 allows the simultaneous extraction of globulins and albumins with yields ≥40%. On the other hand, such pH values also solubilize phenolic compounds that can form complexes with proteins. A diafiltration step by ultrafiltration is necessary to increase protein purity to more than 80% and spray-drying does not seem to be denaturing. Extraction at pH 10 produces native proteins. In their raw state, they show good emulsifying properties. Thermal denaturation greatly reduces their emulsifying properties. Extraction at pH 12 denatures proteins, certainly due to a high surface charge that induces their unfolding. Aggregates probably involving phenols via covalent bonds are formed. However, the solubility of these proteins as well as their emulsifying properties are better than those of proteins extracted at pH 10. Through this manuscript we discussed and tried to understand the differences observed between the proteins extracted at pH 10 and pH 12

Prema najnovijim istraživanjima modifikovanim skrobovima može se pripisati još jedna uloga – aditivi u pekarstvu, s obzirom da utiču na poboljšanje kvaliteta hleba iusporavaju proces starenja. Međutim, prema saznanjima autora ove disertacije, nepostoje istraživanja na temu uticaja emulgujućih skrobova (skrob-natrijumoktenilsukcinata, OSA skrobova) na kvalitet testa i hleba od pšeničnog brašna.Uzimajući u obzir činjenicu da druge vrste modifikovanih skrobova ispoljavaju dobreosobine u smislu poboljšanja kvaliteta hleba i da je OSA skrob nutritivno vrednasirovina, s obzirom da se u organiznu ponaša kao prehrambeno vlakno, od velike jevažnosti ispitati ulogu OSA skroba kao aditiva u pekarstvu.Međutim, usled kompleksne prirode testa kao sistema, bilo je teško odrediti relativniuticaj pojedinačnih komponenti (proteina, pšeničnog skroba, OSA skroba) i njihovihmeđusobnih interakcija na osobine testa. Stoga je, u cilju rasvetljavanja uticaja različitih OSA skrobova na viskoelastične osobine testa i retrogradaciju skrobne komponente (fenomen povezan sa starenjem hleba), pšenično brašno frakcionisano na gluten i skrob, i vršena su ispitivanja strukturnih, reoloških i termičkih osobina hidratisanog glutena i skrobnih gelova sa dodatkom OSA skroba. Takođe su pripremani i model sistemi testa.Ispitivanja na realnim sistemima (testo i hleb) izvođena su zamenom 2,5; 5 i 10%pšeničnog brašna, jednim od tri vrste OSA skroba: skrob-natrijum oktenilsukcinatom(OSA-ST), preželatiniziranim skrob-natrijum oktenilsukcinatom (Pregel OSA-ST) ihidrolizovanim sušenim u spreju skrob-natrijum oktenilsukcinatom (Hydrol OSA-ST).Cilj je bio da se ispita uticaj dodatka OSA skrobova na strukturu testa (SEM), empirijske (miksolab, alveograf i reofermentometar) i fundamentalne (oscilatorna merenja i testovi puzanja i deformacije) reološke osobine, kao i parametre kvaliteta hleba (specifična zapremina, boja kore i sredine hleba, vlaga sredine hleba, parametri raspodele veličine pora i tekstura sredine). Pored pomenutog, praćena je i promena kvaliteta hleba tokom skladištenja, kako bi se dobio uvid u kinetiku starenja hleba.Rezultati dobijeni u ovoj disertaciji ukazali su da reološko ponašanje testa sa dodatkom OSA skrobova zavisi od strukture skrobnih granula, tj. od stepena dezintegracije i depolimerizacije granule tokom procesa modifikacije. Stoga je dodatak OSA-ST doveo do ojačavanja glutenske mreže što se odrazilo na porast modula elastičnosti i testa i glutena. Nasuprot tome, Pregel and Hydrol OSA-ST uticali su na kontinualnost glutenske mreže koja je u njihovom prisustvu bila poroznija, a time su i dobijena testa bila mekša i rastegljivija. Istraživanja na realnim i model sistemima (pšenični skrob sa dodatkom OSA skroba) ukazala su da sva tri OSA skroba usporavaju retrogradaciju pšeničnog skroba. Takođe je dokazano da svi ispitivani emulgujući skrobovi povećavaju specifičnu zapreminu hleba u poređenju sa kontrolnim, pri čemu je Pregel OSA ispoljio najjači efekat. To se odrazilo i na strukturne osobine sredine hleba, a posledično i na mehaničke osobine sredine, čija promena je praćena u cilju određivanja kinetike starenja hleba. Prema dobijenim rezultatima, vrednosti čvrstoće sredine hleba koji je sadržao OSA-ST i Pregel OSA-ST su i nakon 24 h bile slične ili značajno niže od vrednosti čvrstoće kontrolnog uzorka određene 2 h nakon pečenja.
Recent studies have demonstrated that modified starches can be used as novel additives in breadmaking since they improve bread quality and retard stalling. However, up to the author's knowledge, there are no investigations concerning the influence of emulsifying starches (starch sodium octenyl succinates - OSA starches) on wheat flour dough and bread quality. Taking into account the fact that other modified starches have exhibited significant bread improving properties and that OSA starch has special nutritional value since it can act as functional fibre, it is of a great importance to investigate the feasibility of OSA starch as bread improver.However, due to the complex nature of dough, it was difficult to determine the relative contributions of protein, native and modified starch components and their interactions on dough properties. Therefore, in order to resolve the influence of different OSA starches on dough viscoelastic properties and starch retrogradation (the phenomenon related to bread stalling), wheat flour was fractionated into gluten and starch; and the structural, rheological and thermal behaviour of the hydrated gluten samples and starch gels supplemented with emulsifying starches was also studied. Dough model systems were also prepared.Experiments on real systems (dough and bread) were performed by incorporatingstarch sodium octenyl succinate (OSA-ST), pregelatinized OSA starch (Pregel OSA-ST) and hydrolysed spray-dried OSA starch (Hydrol OSA-ST) at 2.5, 5 and 10 % into wheat flour. The aim was to investigate the effect of incorporating OSA starches on dough structural (SEM imaging), empirical (Mixolab, Alveograph, Rheofermentometre) and fundamental (oscillatory and creep measurements) rheological properties as well as bread quality parameters (specific loaf volume, crust and crumb colour, crumb moisture, crumb grain features, crumb texture). In addition, the bread quality attributes during storage were also monitored in order to get insight into bread stalling kinetics.The results obtained in this thesis revealed that the rheological behaviour of OSA starch supplemented dough depended on the OSA starch granule rigidity, i.e. extent of OSA starch granule disintegration and polysaccharide degradation during modification. OSA-ST starch caused a reinforcement of the gluten network, as shown by the increase in storage modulus of doughs and gluten. On contrary, Pregel and Hydrol OSA-ST affected the continuity of gluten network which became porous and thus produced softer and stickier doughs in comparison to control. Investigations on real dough and model systems containing wheat and OSA starches revealed that all three types of OSA starches reduced starch retrogradation.In general, all the examined emulsifying starches increased bread loaf volume in comparison to control bread with no added polymers, while Pregel OSA starch has expressed the greatest impact. It also reflected on bread crumb structural features and consequently on the crumb mechanical properties which were used for bread stalling monitoring. Firmness values of OSA-ST and Pregel OSA-ST starch supplemented bread crumbs, after 24 h of storage, were similar to or significantly lower than those of control determined 2 h after baking.

Acrocomia aculeata (« moucaya », en créole guyanais) est un palmier indigène de Guyane et d’Amazonie. Bien que ses fruits soient riches en lipides (0,1 à 83% de la matière fraîche pour le mésocarpe du fruit) et en glucides (6 à 98% de la matière fraîche pour le mésocarpe du fruit), seuls les lipides sont valorisés comme sources de biocarburants (biodiesel et biokérosène) dans la sous-région amazonienne, en raison du manque de connaissance sur la nature chimique des glucides. En Guyane, le fruit ne fait l’objet d’aucune valorisation et ses capacités antioxydantes restent mal connues. Pour pallier cela, ce travail de thèse s’articule autour de l’extraction, la caractérisation physico-chimique et structurale des lipides et des glucides (mono-, di-, oligo- et polysaccharides) constitutifs du fruit. Une évaluation de leurs propriétés antioxydantes ou émulsifiantes a été envisagée. Nos expérimentations ont montré que les mésocarpes des fruits contiennent 7 à 17% d’huile par rapport au mésocarpe frais riche avec une composition chimique dominée par les acides oléique (54 – 62%) et palmitique (23 – 29%) conformément aux résultats de la littérature (respectivement 53 – 78 et 11 – 30%). S’agissant des glucides, ces travaux ont permis d’identifier pour la première fois la présence d’oligo- et polysaccharides de glucomannanes originaux (fraction F2, 11 – 22% du mésocarpe frais) avec des propriétés émulsifiantes remarquables observées dans le cas des oligomères (système eau-dans-huile d’olive (25/75, v/v) à 1% p/v ; stabilité > 6 mois). Au niveau des activités antioxydantes, le fruit n’a pas présenté de propriétés notoires. Ces travaux préliminaires ouvrent la voie à de futures investigations dont l’objectif sera de développer pour ces nouveaux glucomannanes des applications dans les domaines de la cosmétique, l’agroalimentaire ou l’industrie pharmaceutique
Acrocomia aculeata (« moucaya », French Guiana creole) is a palm native to French Guiana and the Amazon. Although its fruits are rich in lipids (0.1 to 83% of fresh matter for the mesocarp fruit) and carbohydrates (6 to 98% of fresh matter for them esocarp fruit), only lipi ds are valued as source of biofuels (biodiesel and biokerosene) in the Amazon sub region, due to a lack of knowledge about thechemical nature of carbohydrates. In FrenchGuiana, the fruit is not subject to any valorizationand its antioxidant capacities remain poorly known.To overcome this situation, this thesis work focuses on the extraction, physico chemical and structural characterization of the lipids and carbohydrates (mono --, di --, oligo and polysaccharides) constitutive of the fruit. An evaluation of their antioxidant oremulsifying properties, was also considered. Ourexperiments showed that fruit mesocarps contain 717% oil compared to rich fresh mesocarp, with a chemical composition dominated by oleic (54 62%) and palmitic (23 29%) acids, in line with literature results (53 78 and 11 30% respectively). Regarding carbohydrates, this work identified for the first time the presence of original glucomannanoligo and polysaccharides (fraction F2, 11 22% offresh mesocarp) with remarkable e mulsifyingproperties observed in the case of oligomers (waterin olive oil system (25/75, v v ) at 1% w/v; stability >6 months). In terms of antioxidant activity, the fruit showed no note worthy properties. This preliminary work paves the way for future in vestigations aimed at developing applications for these new glucomannans in the cosmetics, food, and pharmaceutical industries

La gomme arabique exsudée par Acacia senegal est un polymère naturel hétéropolymoléculaire parfaitement hydrophile. L'étude physico-chimique d'exsudats d'Acacia senegal, bien identifiés botaniquement, issus de populations artificielles du Nord Ferlo (Sénégal) permet d'établir la variabilité des valeurs de viscosité, de pouvoir rotatoire et de teneur en azote. Nous avons cherché des corrélations des différents paramètres entre eux et des paramètres physico-chimiques avec les conditions climatiques et édaphotopographiques de la gommeraie. Afin d'améliorer les propriétés émulsifiantes de la gomme arabique, nous avons modifié chimiquement ses chaînes en accentuant le caractère hydrophobe. La caractérisation des produits greffés et de la gomme arabique a été réalisée par des mesures de tension superficielle, de conductimétrie et de viscosimétrie de cisaillement. De même, le comportement en émulsion de chacune des gommes a été étudié

Des lipopeptides amphipathes ont ete synthetises : suivant la methode utilisee. On obtient des lipsamino-acides ou des lipopeptides ; etude par diffraction x, proprietes tensio-actives, pouvoir emulsifiant. Par le test d'hemolyse, il a ete montre que certains lipopeptides ont une hemocompatibilite similaire a celles des meilleurs tensio-actifs bicatenaires

碩士
國立臺灣海洋大學
食品科學系
107
Mayonnaise is one of the most widely used sauces in the world. It is an oil-in-water emulsion containing 70% fat. Mayonnaise is a mixture of egg yolk, water, vinegar and stabilizer. In this study, we explore the effects of these ingredients on the emulsion system. Among the commercially mayonnaise products, the Taiwan-style mayonnaise has an additional addition of an emulsifying stabilizer and an antioxidant to maintain the stability of the product, while the Japanese-style mayonnaises do not add and can be placed at room temperature. The pH of Japanese vegetable sauce is more than 4.6, so it was under high-temperature sterilization to avoid the growth of pathogens. The emulsification characteristics test using various combinations of mayonnaise found that the oil mainly affects the particle size and viscosity of the oil droplets. The increase of oil content will cause the decrease of oil droplet size and the increase of viscosity. When the oil ratio increased by 25%, the droplet size was reduced by 0.9 μm and the viscosity was increased by 53568 cP. The egg yolk content affects the emulsifying activity, emulsion stability, oil droplet size and viscosity. When the ratio of egg yolk is increased from 70 to 100%, the oil droplet size is reduced by 5 μm, the emulsifying activity is increased by 14.5%, and the viscosity is increased by 5984.9. cP, the emulsion stability reached to 100% when the egg yolk was added to 37.5 %. The addition of vinegar caused the aggregation, but has no significant effect on the emulsifying activity. Using Tremella fuciformis as an emulsifying stabilizer, it was found that there was no significant difference in the emulsion stability compared with the xanthan gum, which was widely used in commercial product, cause the emulsifying activity increase by about 15 %. In terms of freeze-thaw stability, Tremella fuciformis can effectively inhibit the oil separation of mayonnaise, from 29.1% to 3.1%. Therefore, at the ratio of 50% vegetable oil and 30% egg yolk, added Tremella fuciformis to make the mayonnaise stability to avoid the collapse after freezing and thawing, and increase the possibility of using the frozen transportation.

Thesis (M.S.)--University of Wisconsin--Madison, 1998.
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The influence of pH (3.0, 5.0 and 7.0) and ionic strength (0, 50 and 100 mM NaCl) on the physicochemical and emulsifying properties of cruciferin-rich (CPI) and napin-rich (NPI) protein isolates were examined. Specifically, the surface characteristics (charge and hydrophobicity), solubility, interfacial tension and emulsifying activity (EAI) and stability (ESI) indices were measured. In the case of the cruciferin-rich protein isolate, surface charge was found to be negatively and positively charged at pHs above and below its isoelectric point (~4.6-4.8), respectively, ranging in potential from -33 mV at pH 8.0 to +33 mV at pH 3.0. In the presence of NaCl, the overall magnitude of charge became reduced at all pHs. In contrast, hydrophobicity, solubility and the ability for CPI to reduce interfacial tension all were found to be dependent upon both pH and NaCl concentration. Solubility was found to be lowest at pH 5.0 (~11%) and 7.0 (16%) for CPI without salt, but was significantly improved with the addition of NaCl (>80%). Interfacial tension was found to be lowest (10-11 mN/m) for pH 5.0 – 0 mM NaCl and pH 7.0 – 50/100 mM NaCl. Overall, the presence of salt reduced EAI with increasing levels of NaCl at pH 5.0 and 7.0, but not at pH 3.0. In contrast, ESI became reduced with the addition of NaCl (regardless of the concentration) from ~15.7 min at 0 mM NaCl to ~12 min with 50/100 mM NaCl, from ~14.7 min at 0 mM NaCl to ~11.5 min with 50/100 mM NaCl and from 15.1 min at 0 mM NaCl to ~11.7 min with 50/100 mM NaCl for pH 3.0, 5.0 and 7.0, respectively. ESI also was found to be unaffected by pH. In the case of a napin-rich protein isolate, surface charge for the NPI in the absence of NaCl ranged between ~ +10 mV to ~ -5 mV depending on the pH, becoming electrically neutral at pH 6.6. The addition of NaCl acted to reduce the surface charge on the NPI and caused a shift in its isoelectric point to pH 3.5 and 3.9 for the 50 and 100 mM NaCl levels, respectively. Overall, surface hydrophobicity for the NPI was reduced as the pH increased, whereas as NaCl levels were raised the hydrophobicity declined. In contrast, NPI solubility was found to be high (~93-100%) regardless of the solvent conditions. The ability of NPI to reduce interfacial tension was enhanced at higher pHs, however the effect of NaCl was pH dependent. Overall, EAI values were similar in magnitude at pH 3.0 and 5.0, and lower at pH 7.0. The effect of NaCl on EAI was similar at pH 3.0 and 7.0, where EAI at the 0 mM and 100 mM NaCl levels were similar in magnitude, but increased significantly at 50 mM NaCl. However, the EAI values at pH 5.0 were reduced as the level of NaCl increased. Overall, the stability of NPI-stabilized emulsions degraded rapidly and the addition of salt induced faster emulsion instability. In summary, CPI and NPI were very different in terms of their physicochemical properties. However, the emulsifying properties were similar in magnitude indicating that they had similar emulsifying potential under the solvent conditions examined.

Life as we know it originated in water and the interactions between water and organic compounds has been one of the forces that directs life forms on earth. Thirty five years ago, Kauzmann (1959) introduced the concept of the “hydrophobic effect” and suggested it to be the main stabilizing force of the native conformation of proteins. Geometric constraints in most proteins prevent the shielding from solvent of all hydrophobic residues, thus in the native conformation of most proteins, some hydrophobic groups are exposed or solvent accessible. These exposed residues have a potential influence on several protein functions. In order to fully understand these functions, quantification of exposed or effective protein hydrophobicity is essential. Fluorescence probe methods are widely used in food protein studies to estimate surface hydrophobicity, however, controversy still exits about the mechanisms and type of interactions involved in these methods. The purpose of this thesis was to critically compare different sectroscopic methds for their potential to the study surface hydrophobicity of a group of 10 purified food proteins. The protein group consisted of the main proteins from cow’s milk [formula] and some egg white proteins (ovalbumin, lysozyme, ovotransferrin and ovomucoid). The proteins were analyzed in their native state or in four different urea concentrations (2, 4, 6, and 8 M). Five different methods were evaluated: 4th derivative UV absorption and two-dimensional fluorescence spectroscopy, which are two methods not commonly used for food proteins; nuclear magnetic resonance (NMR) and Raman spectroscopy, two techniques not previously used for the study of protein hydrophobicity; and a fluorescence probe method using anilino-naphthalene-sulphonate (ANS) and cis-parinaric acid (CPA). Fourth derivative UV absorption as well as fluorescence spectroscopy give information related only to aromatic amino acids, mainly Trp and Tyr residues, while both NMR and Raman spectroscopies have the potential of detecting aliphatic as well as aromatic groups. A second objective of this work was to relate the information obtained with the different spectroscopic methods to the emulsify-ing properties (i.e., emulsion activity and emulsion coalescence stability) of the proteins. Within this objective, the technique of artificial neural networks (ANN) was evaluated as a new methodology for the development of structure-functionality relationships in food proteins. The well established spectral changes due to unfolding were observed in both UV-absorption and fluorescence spectroscopy. Urea caused a blue shift in the UV-absorbance spectra of most proteins. Deconvolution of the spectra by computing its fourth derivative was very useful in detecting the relatively small shifts and in assigning spectral regions to specific side chain type, yielding parameters which were significantly correlated with (log) ANS and (log) CPA hydrophobicities. Urea caused marked changes in the fluorescence spectra ofmost proteins, causing a red shift in the emission peak position and decreased in fluorescence intensity, suggesting exposure of Trp and Tyr residues to solvent and collision quenching of fluorescence. For three proteins (a-lactalbuinin, f3-lactoglobulin and ovotransferrin) fluorescence intensity increased as urea concentration increased. This phenomenon has been previously reported to occur for the denaturation of the two whey proteins but not for ovotransferrin unfolding. The width of the emission peak as well as the shape parameter of peak asymmetry were also affected by urea. A significant correlation was found between the position of the emission peak at an excitation wavelength of 290 nm and (log)ANS (r0.485, n=40, p=O.002) and (Iog)CPA (r=O.453, n=40, p=O. 004). Urea denaturation simplified the NMR spectra of the proteins, the degree of change depended on the protein and urea concentration. The NMR spectra of the proteins in 8 M urea were similar to those calculated assuming random coil conformation. Using basic principles of NMR, linewidths were used as a crude estimate of mobility/exposure. Proteins with less ordered conformation (e.g., caseins) had NMR resonances with smaller linewidths than more compact and globular proteins (e.g., a-lactalbumin, lysozyme). Significant correlations were found between linewidths of the methyl proton signal of the native proteins and their ANS and CPA hydrophobicities. The emulsifying properties were also significantly correlated to the methyl signal linewidths. Urea denaturation also caused a downfield shift of the main aliphatic peaks. This was in accordance with several reports, which have indicated that buried residues tend to present upfield shifts as compared to the residues in a standard state. Using a set of assumptions, a computer program was written to estimate the number of exposed aliphatic residues (lie, Leu and Val) employing information of the experimental NMR methyl peak. For native proteins, this calculated “aliphatic exposure” was significantly correlated to ANS and CPA hydrophobicities. A NMR cross saturation experiment was also used to estimate exposure of hydrophobic residues of proteins. For native proteins, a highly significant regression model(R2=0.992, F=240, n=8) was found relating the change in NMR integrated areas due to cross saturation and CPA hydrophobicity. Contrary to the large changes observed by NMR spectroscopy, urea caused only small changes in the Rainan CH stretching area of proteins. The broadness ( 100 cm’) of tlils protein Raman region, caused difficulties in detecting spectral alterations. Maximum likelihood deconvolution was used to expand and quantify these changes. Four deconvoluted peaks were found to form the broad CH stretching area. Caseins tended to have peaks at higher Raman shifts and with larger linewidths than whey and egg proteins. Signfficant regression equations were derived relating some parameters from these peaks to ANS and CPA hydrophobicities and to the emulsion properties of the proteins. In order to relate the large number of spectroscopic variables to the two emulsifying properties, principal components regression (PCR) and artificial neural networks (ANN) were used and compared. The prediction ability of ANN was found to be superior to that of PCR, especially with cross validation. Overall, these results support the use of fluorescence probes for the estimation of surface hydrophobicity of food protein. Of the several spectroscopic methods evaluated, NMR spectroscopy may have the greatest potential for analysis of surface residues of proteins. Results also indicated the great potential of ANN in elucidating the structure-functionality relationships of proteins.

碩士
國立中興大學
動物科學系所
106
Milk fat globule membrane (MFGM) is rich in biologically active substances, including phospholipids, glycoproteins and others, which in turn are characterized as having emulsifying properties of phospholipids. MFGM is known to be composed mainly of polar lipids and proteins which encloses the fat droplets in milk and contributes to stabilizing milk as an emulsion. Generally, the commercial ice cream has a high fat content of more than 10%. Therefore, it is necessary to add an appropriate emulsifier to avoid oil-water phase separation. Furthermore, in recent years, consumers have paid attention to the concept of health and natural food. So, the purpose of this study was to evaluate the emulsion properties of MFGM and its application to ice cream manufacture as a replacer for commercial emulsifier. The MFGM obtained from microfiltration with either sodium citrate (SC) or hydroxyapatite (HA) pretreatment. The emulsion properties of SC and HA (0.25%, 0.1%, 0.2%, 0.5% and 1.0%), non-fat dry milk powder (NFDM), buttermilk powder (BTM), and deionized water (Control) were compared in a soy bean oil system. The micrograph showed that the emulsifying property was higher in the high concentration of all MFGM, where the 1.0% concentration of milk fat globule membrane treatment group with no matter SC or HA treatment showed the smallest particle size, indicated that the better emulsifying property of them. The texture evaluation of ice cream showed that the ice cream group with milk fat globule membrane as the natural emulsifier had the slowest melting rate, and the overrun of the HA group was significantly higher than that other treatment groups. The sensory evaluation of ice cream showed that the overall flavor acceptance and texture of the ice cream during storage for six months were shown in both HA and SC group, where there were not significantly different from commercial group (p ＜ 0.05). In summary, MFGM has a certainly emulsifying property, and has the potential for application as a natural emulsifier for ice cream.

碩士
國立臺灣海洋大學
食品科學系
92
Abstract Commercial product of saponins from quillaja (Sigma:QS1, ICN:QS2), tea seed (TSS), soybean (SS) and cowpea whey powder (CWP, laboratory prepared) were used as materials. The emulsifying properties of various saponins and their effects on cholesterol solubility were also investigated. With increasing the saponins and CWP concentration of solution (0-2%), the highest emulsifying activity (EA) found in QS1 was increased from 60.0 to 68.2%; and the highest emulsion stability (ES) in CWP was increased from 62.1 to 86.7%. Polysaccharides were used as stabilizers in emulsion system. The EA of QS1, QS2, TSS, SS and CWP reached 100% as the xanthan gum was added at the concentration of 0.6%. The highest EA and ES were found in QS1, and the values were increased from 60.8 to 68.6% and 57.5 to 66.0%, respectively, as κ-carrageenan was added up to 0.2%. The EA and ES of QS1, QS2 and TSS remained at 100% as the NaCl concentration ranged from 0 to 0.6%. With the increase of NaCl concentration, the EA and ES of SS decreased from 100 to 57.6% and 9.3 to 2.5%, respectively. However, the EA and ES of CWP increased from 86.1 to 92.9% and 83.8 to 94.9%, respectively, when the pH of the sample solution was adjusted at 3, 5 and 7, the EA and ES of QS1 and QS2 remained unchanged , but the ES of TSS decreased with increasing pH of solution. And, the EA and ES of SS and CWP increased with increasing pH of solution. The highest cholesterol solubility 8.3 mg/dl was produced by SS with the concentration of 2.5%(w/v).

There has been growing interest in the utilization of plant-derived proteins as functional ingredients in many food and beverage applications because they are perceived as being more sustainable, healthy, and ethical than animal-derived proteins by many consumers. Traditionally, soy proteins have been the most widely employed plant protein in the food industry. However, a number of alternative plant-based protein sources have recently become available, with pulse proteins being one of the most popular. In this study, the physicochemical properties and functional attributes of various commercially available pulse protein isolates were compared with those of soy protein isolate to evaluate their potential application in foods and beverages. The water holding capacity, oil holding capacity, gelation properties, emulsifying properties, and color of faba bean (FPI), pea (PPI), lentil (LPI), and soy (SPI) protein isolates were therefore measured. SPI had a significantly higher water holding capacity (7.6 g/g) than the pulse protein isolates (2.2-5.1 g/g). Among the plant protein isolates, PPI had a significantly lower oil holding capacity and gelling property. LPI was more effective at producing small oil droplet sizes during homogenization than the other protein isolates. Nevertheless, all of the plant proteins were capable of forming relatively small oil droplets (D32 = 1-3 mm) at a protein-to-oil ratio of 1:10. As expected, droplet size decreased with increasing protein concentration for all plant protein isolates, which increased their resistance to creaming. These results suggest that pulse proteins may have similar or better techno-functional properties than soy proteins for certain applications. In particular, lentil proteins were more effective emulsifiers, whereas faba bean proteins were more effective gelling agents. These proteins may therefore be suitable for application in plant-based milks, eggs, cheese, or meats where emulsifying or gelling properties are required.

Self-emulsifying systems are mixtures of oils and surfactants, ideally isotropic, sometimes including cosolvents, which emulsify under conditions of gentle agitation, similar to those which would be encountered in the gastrointestinal tract. The process of self-emulsification has remained the center of attraction for most researchers. Controlled hydration of self-emulsifying systems shows formation of an intermediate gel phase which upon rupture forms an emulsion. Current work was undertaken to understand and explore the microstructural properties of intermediate gel phase which are believed to influence the performance (droplet size) of the final formulation. The effect of additives on microstructural properties of intermediate gel phase has also been investigated. Microstructural elucidation of hydrated samples of intermediate regimes was done by using techniques such as small angle X-ray scattering, differential scanning calorimetry and rheology. Samples from intermediate regimes showed formation of local lamellar structure which swelled with hydration. In the present work, the effect of addition of salt form of naproxen (sodium and potassium) and naproxen (base) on microstructural properties of intermediate regimes was investigated. Systems containing naproxen salts formed larger droplets whereas naproxen base formed smaller ones. Microstructural properties of intermediate lamellar structures were well correlated with performance of the final formulation. The current studies indicate that by controlling the properties of intermediate regimes optimized formulations with desired performance can be tailor-made.

碩士
靜宜大學
食品營養學系
103
Mannoprotein found in the cell wall of Saccharomyces cerevisiae is composed of 5–20% protein and 80–90% mannose and responsible for most cell surface properties of yeast. The mannoprotein is generally link mannose to protein through covalent bond and associated to the residues of D-glucose and N–acetylglucosamine. Numerous studies have clearly proven the multiple applications of mannoprotein, such as wine quality improvers and stabilizers bio-emulsifier. In this study, yeast mutants were generated by UV light irradiation or chemical mutagen. Killer-9 toxin was used to screen mannoprotein over-expression strains, and then the selected strain with the lowest glucose/mannose ratio in its cell wall was used to ferment Kyoho grape (Vitis vinifera L.) for wine production. One chemical induced mutant (CM8) was selected as the starter and the ratio of glucose/mannose in its cell wall was 1/3.6 (wild-type strain is 1: 2.1). Mannoprotein content in the cell wall of CM8 was 386.8 mg/g while the content in the wild-type strain was 340.1 mg/g. Alcohol tolerance of CM8 was better than that of the wild-type strain, and the cell count of CM8 was significantly higher than that of the wild strain after 72 hr incubation. In addition, after 72 hr incubation, the alcohol conversion rate of CM8 was the same as that of the wild strain. These results showed that CM8 has the potential to serve as a wine fermentation starter. Red wines produced by CM8 (CM-wine) contained 137.4 mg/L tartaric esters, 1.01 g/L titratable acidity, 1174.73 mg/L total phenolics and 403.75 mg/L tannins. The tartaric esters content in CM-wine was significant lower than that in red wine produced by the wild strain (SC-wine) (146.9 mg/L), but the tannin content in CM-wine (403.75mg/ L) was higher than that in SC-wine (310 mg /L). However, the results of sensory evaluation showed that CM-wine had higher consumer preference than SC-wine. Moreover, the astringency degree of CM-wine indeed lower than the SC-wine. The mannoproteins extracted from the cell wall of CM8 had a good emulsion stability (60 %E24) when mixed with plam oil, even higher than the emulsion stability of lecithin (52 %E24). Therefore, this study concluded that S. cerevisiae mutant strain CM8 could serve as a wine fermentation starter to produce high quality of red wine. It had high mannoproteins in its cell wall, and thus, it could effectively reduce the formation of tartaric acid and the astringency of the wine, and increase the stability of wine color. In addition, the mannoprotein extracted from CM8 had the potential to be a commercial bio-emulsifier.

碩士
國立嘉義大學
食品科學系碩士班
91
Hen eggs were firstly separated into egg white and yolk and, then the egg yolk was homogenized and filled into inedible acetate cellulose casing. It was then soaked in 5 % of acetic acid, lactic acid and citric acid solutions, respectively for 24 hours. After acidic soaking, the weights of egg yolk in these three acid solutions increased for 22~32% with increasing soaking time during 24 hours, the lactic acid treatment having the greatest increase in weight. In addition, the pH values of egg yolk decreased from 6.0 to 3.6~2.6 with the citric acid treatment having the greatest decrease. The viscosity of egg yolk was slightly increased in the beginning, and then decreased after 2 to 24 hours’ soaking. When acid was added into egg yolk solutions directly to reach the same pH as soaking method, the result shows that as the pH get lower, the viscosity get higher. Aggregation phenomenon of proteins in egg yolk was observed due to acid osmosis effect. The turbidity increased with increasing soaking time, but the trend was level off after soaking for 2 hours. The content of soluble proteins in egg yolk decreased from 139.5 mg/ml to 117.4 mg/ml after 24 hours soaking. Initially, the surface hydrophobic intensity was slightly decreased, but it was then increased with increasing soaking time afterwards. In the case of lactic acid soaking, after 24 hours, the value of hydrophobic intensity rose to 691 So/mg protein. On the other hand, the amount of surface sulfhydryl group of fresh hen egg yolk was 5.9 mmole/ g protein, if increasing acidic soaking to 24 hours, the value was lifted to 32.5 mmole/g protein. In SDS-PAGE profile, it was not significantly different for hen egg yolk after acidic soaking. The results between acidic soaking and direct addition of acids had the same trend at the same pH value, except for viscosity. For emulsifying properties, the emulsifying activity and emulsifying stability increased with increased egg yolk concentration from 0 to 2 %, however, the trend was not so obvious after 0.5 % concentration. At initial stage, emulsifying activity and emulsifying stability was better, but it was decreased with increased soaking time at a later stage. In SDS-PAGE, to assay adsorbed and unadsorbed proteins in oil-in-water emulsions of egg yolk, it was found that at pH=4.6~5.5, egg yolk proteins adsorption was better. The results had the same trend for both acidic soaking and direct addition of acidic solutions. After acidic soaking, the hen egg yolk was heated at 100℃ for 30 minutes, the gel strength and gel rigidity before soaking was 377.2 (g*cm) and 806.2 (g/cm), after 24 hours soaking, these two values were reduced to 39 (g*cm) and 101.7 (g/cm), respectively. This indicates that the properties of gel were broken down with increased acidic soaking time, and there are no significant differences among acids. Changes of acid-soaked egg yolk on viscoelastic properties detected by dynamic rheometer showed that, if increasing soaking times, the storage modulus was decreased, and the transition temperature was decreased at the same time. The microstructure of egg yolk gel both with acidic soaking and without acidic soaking was observed by scanning electron microscopy (SEM). The results show that, at initial stage, the network structure among yolk molecules was tighter. In a later period of acidic soaking, network structure was quite hollow, and there was no noticeable difference among three acid treatments.

碩士
國立嘉義大學
動物科學系碩士班
93
The aim of this study was to evaluate the physicochemical and dynamic rheological characteristic of raw and cooked pork skin as affected by different marinated acid-alkaline mixed solutions. Above all, it was to use the first and double scalded by low (60-65℃) and high (80-90℃) temperature pork skin from hog carcass, with experimental marinated acid-alkaline mixed solution design was divided into three groups: treatment groupⅠcontaining 0.2% lactic acid, citric acid, sodium tripolyphosphate and sodium bicarbonate(V/V; W/V), treatment group Ⅱcontaining 4.0% L 96 S solution(V/V), treatment group Ⅲcontaining 0.1% lactic acid, citric acid, sodium tripolyphosphate sodium bicarbonate (W/V) and 2.0% L 96 S solution (V/V). First and double scalded raw pork skin were both soaked 1 kg in acid-alkaline mixed solution, and were marinated at 4℃ for 72 hrs respectively. 0.5 kg raw pork skin was taken from first (B, C, D three groups) and double scolded (F, G, H three groups), and was cut into raw pork skin paste. On the other hand, the rest of 0.5 kg raw pork skin taken from first and double scolded was cooked by heating at 60℃ for 5 mins, that were cut into cooked skin caste as to be B1, C1, D1 three groups (first time scolded pork skin paste) and F1, G1, H1 three groups (double scolded pork skin paste). The SDS-PAGE, dynamic rheological behavior, pH value, moisture contents, ash, crude protein, color difference, 2-Thiobarbituric acid (TBA) value, gumminess, emulsifying capacity, and total plate counts of pork skin paste samples were determined. Analyzing by applying SDS-PAGE from all samples, 24kDa, 45kDa, 55kDa, 66kDa, 84kDa, 116-205kDa, beyond 205kDa pastern bands were analyzed by SDS-PAGE, and 24kDa and 45kDa of two bands were merely discovered from B, F, H and F1 groups. The consistency of β-chain and α-chain of polymer of the first time scalded was identified higher than double scalded. It was observed B and B1 groups collagen of pork skin had the higher storage modulus (G´) than others, and B1 group had the highest storage (G´) and loss (G〞) modulus value based on the dynamic rheological behavior. Furthermore, the storage modulus and loss modulus of first time scalded raw and cooked skin pastes were better than double scalded raw and cooked pork skin pastes because they were influenced by salts and heated on electrostatic interaction and hydrophobic bonds of collagen. The decrease of pH value tends to cause the increase of swelling of the first and double scalded pork skins and the moisture content of raw and cooked pork skin of first time scalded pork skin, and C group was more than the other (P<0.05). To compare with double scalded by high temperature pork skin moisture content of first time scalded pork skin seemed to be higher. C and C1 treatment groups of ash content seemed to be slightly higher. D and D1 treatment groups of crude protein content were significantly higher than others (P<0.05). F, F1 groups and H, H1 groups of crude protein content were significantly higher than G, G1 groups, in addition, crude protein content of the raw and cooked of first time scalded pork skin may have the tendency to be higher than double scalded pork skin. L value, Red color (a value) and yellow color (b value) were influenced by acid-alkaline mixed solutions (P<0.05). However, L value of samples were significant decreased, and b value increased by heating . TBA value of B, C, D, F, G and H samples were not influenced by acid-alkaline solutions (P>0.05). However, TBA value of B1, C1, D1, F1, G1 and H1 samples tended to be lower than B, C, D, F, G and H samples (P<0.05). Additionally, TBA value of D1 and H1 samples were the lower. The emulsifying capacity of B, C, D, F, G and H samples were higher than B1, C1, D1, F1, G1 and H1 samples (P<0.05), and D and H groups were the best. Gumminess of C, C1, G and G1 groups were higher than others (P<0.05). However, Gumminess of first time scald groups were lower than double scald ones. Total plate counts of all samples were not influenced by heating, and C, D, G and H groups were significant lower than others (P<0.05). In summery, the physicochemical properties of raw and cooked pork skin were regarded the best in first time and double scalded, and emulsifying capacity of D, D1, H and H1 group may be valued the highest.