The physical properties and the stability of alcohol containing emulsions made with sodium caseinate using two types of oil, canola oil and coconut oil, were investigated. The region of emulsion stability was presented on ternary phase diagrams. Emulsion stability was limited to emulsion compositions in the range of sodium caseinate solutions between 32-68 %wt, oil contents between 10-53 %wt and ethanol concentrations from 8 to 32 %wt. The type of oil had a minor effect on emulsion stability, but stability was sensitive to ethanol content and casein/oil ratio. Emulsions were classified as Newtonian fluids, with high ethanol content (> 20 %wt) being low viscosity and those of low ethanol content (< 20 %wt) being of high viscosity. Analysis of emulsion droplet sizes showed that the presence of ethanol affected the average droplet size. From lipid oxidation determinations, there was no clear correlation between casein/oil ratio and concentration of lipid hydroperoxides

The physical properties and the stability of alcohol containing emulsions made with sodium caseinate using two types of oil, canola oil and coconut oil, were investigated. The region of emulsion stability was presented on ternary phase diagrams. Emulsion stability was limited to emulsion compositions in the range of sodium caseinate solutions between 32-68 %wt, oil contents between 10-53 %wt and ethanol concentrations from 8 to 32 %wt. The type of oil had a minor effect on emulsion stability, but stability was sensitive to ethanol content and casein/oil ratio. Emulsions were classified as Newtonian fluids, with high ethanol content (> 20 %wt) being low viscosity and those of low ethanol content (< 20 %wt) being of high viscosity. Analysis of emulsion droplet sizes showed that the presence of ethanol affected the average droplet size. From lipid oxidation determinations, there was no clear correlation between casein/oil ratio and concentration of lipid hydroperoxides

Master of Science / Department of Animal Sciences and Industry / James M. Lattimer / Eight cecally cannulated horses were used in a replicated, 4 x 4 Latin square design conducted in 4, 14-d periods to determine effects of sodium caseinate on equine hindgut fermentation and fiber digestion. Horses were maintained on an ad libitum diet of Smooth Bromegrass hay and treatments consisted of cecal infusions of water (CON), 0.125 g sodium caseinate/kg BW (LOW), 0.25 g sodium caseinate/kg BW (MED), and 0.50 g sodium caseinate/kg BW (HI). Cecal NH3 concentrations increased (P < 0.01) as casein increased. Horses on the CON and MED treatments had greater cecal pH (P < 0.01) than horses on the LOW and HI treatments; however, there was no effect of treatment of fecal pH. Dry matter, OM, NDF, and ADF digestibility were unaffected by treatment (P > 0.10). There were no differences in dry matter intake (DMI), regardless of treatment. There was no treatment effect on cecal acetate, propionate, butyrate, total VFA concentration or acetate:propionate (A:P) ratio. Inter-horse variability and a small sample size may contribute to the lack of statistical differences amongst treatments. Results from this study may imply that medium quality, roughage based protein supplies an adequate level of nitrogen to the microflora of the hindgut. A performance study was conducted to evaluate the effect of strain and method of administration of Megasphaera elsdenii on growth performance in broiler chickens. In Experiment 1, pens were randomly assigned to 1 of 6 treatments: 0.2 mL oral gavage containing 1.97 x 10⁹ CFU/mL of M. elsdenii strain NCIMB 41125 (Lactipro, MS-Biotec, Wamego, KS; O-L), 0.2 mL of fresh culture containing 0 CFU/mL of M. elsdenii strain KS 249 (O-KS; Attempts to grow this strain were unsuccessful), 0.2 mL of a fresh culture containing 1.06 x 10⁹ CFU/mL of M. elsdenii strain B52-2083 (O-B52), aerosolized mist at rate of 15 mL per pen containing 1.97 x109 CFU/mL of M. elsdenii strain NCIMB 41125 (~1.88 mL/bird; MS-Biotec, Wamego, KS; OM), topdressing (mixture of diet and freeze dried M. elsdenii strain NCIMB 41125; TD) containing 1.18 x 10⁷ CFU/g of M. elsdenii strain NCIMB 41125 at a rate of a quarter teaspoon per bird, or negative control that had no contact with the probiotic product. Broilers across all treatment groups showed similar ADFI (P = 0.82), ADG (P = 0.89), gain:feed (P = 0.93), and mortality rates (P = 0.54). In Experiment 2, chicks were assigned to 1 of 2 treatments consisting of lyophilized M. elsdenii strain NCIMB 41125 in the form of a topdressing (TD) or a negative control that had no contact with the probiotic product (C). Average daily gain (P = 0.02) and gain:feed (P = 0.04) were both greater in birds receiving the TD when compared to the C birds. Feed intake (P = 0.70) and mortality rates (P = 0.31) were not different between treatments. Administration of lyophilized M. elsdenii strain NCIMB 41125 may be an effective means to improve growth rate and feed efficiency of broiler chicks.

Orientador: Eunice Oba / Resumo: A congelação de sêmen é uma ferramenta de grande importância na reprodução de animais domésticos, auxiliando na difusão do do material genético, preservando-o por tempo indeterminado, além do maior aproveitamento do uso de reprodutores com genética superior comprovada. Para que a congelação de sêmen seja eficiente e alcance resultados satisfatórios com a inseminação, utiliza-se no processo o emprego de diluentes, que tem como função proteger a célula contra o choque térmico e manter o espermatozoide viável até o momento da inseminação. O uso de frações de leite como meio diluidor tem se tornado muito conhecida e de grande importância no processo, usando, por exemplo, as micelas de caseína que conferem função de proteção da membrana plasmática e manutenção da viabilidade espermática. Levando em conta essas informações, este trabalho teve como objetivo avaliar a ação do caseinato de sódio nas características seminais pós descongelação do sêmen utilizando diluentes a base de gema de ovo (BB) e o mesmo diluente acrescido de caseinato de sódio 2% (BC).No experimento I, foram colhidos 3 ejaculados de 8 animais (n=24) por eletroejaculação, este sêmen foi divido em duas alíquotas, uma era diluída em meio comercial a base de gema de ovo e a outra alíquota diluída no mesmo meio mas acrescido de 2% de caseinato de sódio, em seguida foram envasadas em palhetas francesas com volume de 0,25 ml e refrigerado 4 horas á 5 °C em seguida congelado em nitrogênio líquido. Após a congelação as amo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The reproduction of domestic animals, helping in the diffusion of the genetic material, preserving it indefinitely, in addition to the greater use of reproducers with proven superior genetics. In order for semen freezing to be efficient and achieve satisfactory results with insemination, the use of diluents is used in the process, which has the function of protecting the cell against thermal shock and keeping the sperm viable until the time of insemination. The use of milk fractions as a diluting medium has become very well known and of great importance in the process, using, for example, the casein micelles that provide a protective function of the plasma membrane and maintenance of sperm viability. Taking this information into account, this study aimed to evaluate the action of sodium caseinate on semen characteristics after semen thawed using egg yolk (BB) diluents and the same diluent plus 2% sodium caseinate (BC) In experiment I, 3 ejaculates were collected from 8 animals (n = 24) by electroejaculation, this semen was divided into two aliquots, one was diluted in commercial medium based on egg yolk and the other diluted in the same medium but added of 2% sodium caseinate, then they were packaged in French straws with a volume of 0.25 ml and refrigerated 4 hours at 5 ° C then frozen in liquid nitrogen. After freezing, the samples were evaluated by computerized analysis of sperm movement (CASA), integrity of plasma and acrosomal membranes and generation of superoxide anion... (Complete abstract click electronic access below) / Mestre

Two studies were conducted to evaluate the effects of milk solids on restructured and emulsified turkey rolls. the milk solids used were nonfat dry milk (NFDM), whey protein concentrate (WPC), and calcium caseinate (CC). Turkey rolls consisted of 100% breast meat or 90:10 or 70:30 breast-to-thigh, salt (1%), water (10%), internal or cluster fat (10%), and 3% of various milk solids (WPC, NFDM, CC). The objectives of these studies were to 1) determine which ratio between light and dark meat is preferred; 2) determine which of milk solids evaluated will permit the highest level of dark meat incorporation into evaluated products; 3) determine if there is a mechanism by which milk proteins lighten poultry meat; and 4) determine which milk protein produces the best bind between meat pieces. Panelists were used in the first study to evaluate cooked meat attributes of color intensity, color uniformity, cohesiveness, tenderness, roasted turkey flavor, juiciness, and overall acceptability. The attributes were rated on a seven-point scale. Rolls made with WPC or NFDM scored significantly higher for color uniformity, cohesiveness, roasted turkey flavor, and overall acceptability than rolls made with CC. No differences were noted among treatments for juiciness or toughness with rolls of the same light-to-dark meat ratio. However, the 90:10 rolls were rated significantly more tender than the rolls made with the 70:30 ratio. Rolls containing milk solids had significantly higher yields than the controls. In the second study, rolls were made using the preferred meat ratio (90:10 breast:thigh meat). NFDM and WPC were used as binders, but not CC, since in the first study it was an ineffective binding agent. The second study showed that no whitening or lightening occurred in turkey rolls. This researcher also found that both NFDM and WPC increased bind strength between meat pieces. Controls made without added milk solids had less bind strength between the meat particles. Meat particle size also affected bind strength in finished products, with finely chopped rolls having higher bind strength than coarsely ground rolls. Moreover, the second study had unexpected results indicating that NFDM will prevent development of pink discoloration during refrigerated storage. The penetrometer used for bind measurements is described.

Structure function changes of casein micelles were studied as a function of concentration using a non invasive concentration method, osmotic stressing. A combination of serum analysis, light scattering and rheological measurements were used to characterize the physico-chemical properties of casein micelles. In heated and unheated milk, rheological studies indicated that casein micelles behave as hard spheres of similar volume fractions, if the viscosity changes in the serum phase and the particle particle interactions are taken into account. The differences in the distribution of the heat induced complexes between colloidal and soluble phase affected the colloidal properties of casein micelles. Above 70 g L-1 protein, the protein particles were no longer free diffusing. Re-dilution of the suspensions showed no irreversible aggregation. The data suggested that in the range of concentration studied casein micelles behave as hard spheres. Age gelation was also investigated on heated and unheated concentrated milk. In unheated concentrated milk proteolysis played an important role in imparting an increase in viscosity by causing aggregation of the casein micelles. On the other hand, in heated milk, there was a significant effect of the whey protein aggregates, which increased their interaction with the casein micelles over time. This effect, together with proteolysis caused age gelation in heated concentrated milk. The method of concentration used in this research, osmotic stressing, was then compared to ultrafiltration. It was demostrated that these two methods are not equivalent, as shear and mixing during ultrafiltration cause rearrangements to the casein micells. The differences were clearly demonstrated by adding soluble caseins to the milk before or after concentration. This project brings a better understanding on the effects of concentration on the structure-function of casein micelles and the interactions occurring in milk proteins during concentration.

Orientador: Rosiane Lopes da Cunha / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-10T13:26:21Z (GMT). No. of bitstreams: 1 Perrechil_FabianadeAssis_M.pdf: 19952630 bytes, checksum: 207dab8eceafe0a14ef0feb6d0beb071 (MD5) Previous issue date: 2008 / Resumo: Proteínas e polissacarídeos são amplamente utilizados em emulsões alimentícias como agentes emulsificantes e estabilizantes. Entretanto, a presença de ambos biopolímeros em solução aquosa pode resultar no processo de separação de fases, dependendo das condições de pH e força iônica empregadas. Esse estudo mostrou que é possível a produção de diferentes tipos de emulsões múltiplas através da mistura de emulsões óleo-água (O/A) com uma mistura de biopolímeros de fases separadas. Inicialmente, foram estudadas as propriedades de emulsões óleo água (O/A) estabilizadas por caseinato de sódio (Na-CN) sob diferentes condições de acidificação e aplicação de pressão, além das emulsões estabilizadas por Na-CN e goma jataí (LBG). A maioria das emulsões apresentou separação de fases devido ao mecanismo de cremeação, porém este processo de desestabilização foi reduzido quando existiu o aumento da viscosidade dos sistemas ou a diminuição do tamanho das gotas. A viscosidade das emulsões foi modificada pela adição de maiores concentrações de óleo e biopolímeros, e pela redução do pH em direção ao ponto isoelétrico da proteína. Já a redução do tamanho das gotas foi realizada através de aplicação de altas pressões. A homogeneização a altas pressões promoveu a formação de emulsões com tamanhos de gotas muito reduzidos (entre 0,39 e 1,50 mm), sendo possível a sua utilização para o preparo das emulsões múltiplas. Em uma segunda etapa do trabalho, um diagrama de fases foi construído para identificar a faixa de concentrações de Na-CN e LBG que resultariam em uma solução de fases separadas, bem como as condições de pH e força iônica necessárias para o processo de separação de fases. Assim, as soluções mistas Na-CN ¿ LBG formaram uma fase inferior rica em Na-CN (A1) e uma fase superior rica em LBG (A2), sendo possível a formação de emulsões água-água (A1/A2 ou A2/A1) através da mistura das fases superior e inferior em diferentes razões. A mistura de uma emulsão O/A estabilizada por Na-CN e homogeneizada a alta pressão, com soluções de fases separadas compostas pelas mesmas razões de fase superior e inferior utilizadas no preparo das emulsões A/A resultou na formação de emulsões múltiplas. Estas emulsões foram do tipo óleo-água-água (O/A1/A2) ou do tipo óleo-água/água-água (O/A1-A2/A1), dependendo da composição inicial de biopolímeros no sistema / Abstract: Proteins and polysaccharides are widely used in food emulsions as emulsifying and stabilizing agents. However, the mixture of both biopolymers in an aqueous solution can lead to a phase separation process, depending on the conditions of pH and ionic strength. This study showed that multiple emulsions can be prepared by mixing an oil-in-water (O/W) emulsion with a mixed biopolymer solution that separates into two phases. Initially, the oil-in-water emulsions (O/W) stabilized by sodium caseinate were studied at different conditions of acidification and high-pressure homogenization. Emulsions stabilized by Na-CN and LBG were also studied. Most of the emulsions showed phase separation due to the creaming mechanism, but this destabilization process was reduced with the increase of system viscosity and the decrease of oil droplet size. The emulsion viscosity was changed by addition of greater oil and biopolymer concentrations and by reduction of pH in direction to protein¿s isoelectric point, while reduction of droplet size was obtained by application of high pressure. The high-pressure homogenization promoted the formation of very small droplets (between 0.39 and 1.5 mm), which favored the production of multiple emulsions. In a second step of this work, a phase diagram was constructed to identify the range of sodium caseinate (Na-CN) and locust bean gum (LBG) concentrations where phase separation occurred and the conditions of pH and ionic strength that led to the incompatibility between them. Thus, in this conditions, the Na-CN ¿ LBG mixed solution formed a two-phase system consisting of a Na-CN ¿ enriched lower phase (W1) and a LBG ¿ enriched upper phase (W2). Water-in-water emulsions (W1/W2 or W2/W1) could be formed by blending incompatible upper and lower phases together at different ratios. Thus, multiple emulsions were prepared by mixing the O/W emulsions homogenized at high-pressure with the same incompatible solutions used to prepare the W/W emulsions. The produced multiple emulsions were the oil-in-water-in water (O/W1/W2) type or the mixed oil-in-water/water-in-water (O/W1 - W2/W1) type depending on the initial biopolymer composition of the system / Mestrado / Mestre em Engenharia de Alimentos

Orientadores: Rosiane Lopes da Cunha, Fernanda Yumi Ushikubo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-24T02:34:58Z (GMT). No. of bitstreams: 1 Barbosa_JanainaMiranda_M.pdf: 4341938 bytes, checksum: e5e24c14ce9831be45d250772d8a9f57 (MD5) Previous issue date: 2013 / Resumo: As emulsões estão presentes naturalmente em alguns alimentos ou são aplicadas devido a suas propriedades tecnológicas. Porém, as emulsões são termodinamicamente instáveis e tendem a separar de fases com o tempo. A estabilidade das emulsões pode ser melhorada utilizando agentes emulsificantes e estabilizantes. Neste trabalho foi estudada a ação simultânea de dois biopolímeros naturais para melhorar a estabilidade cinética de emulsões óleo - em - água (O/A). Conjugados formados por caseinato de sódio e goma jataí foram produzidos através da reação de Maillard em diferentes razões de proteína/polissacarídeo e tempos de reação, a fim de se obter melhor ação estabilizante que os biopolímeros individuais em emulsões preparadas em duas condições de pH. A formação dos conjugados foi confirmada pela análise de eletroforese em gel de poliacrilamida que evidenciou a presença de compostos de alta massa molecular. De modo geral, em pH 7 as emulsões foram mais estáveis que em pH 3,5, pois em pH neutro a proteína estava mais distante do seu ponto isoelétrico, sendo assim mais solúvel e carregada negativamente, resultando na repulsão eletrostática entre as gotas. As análises de microscopia confocal feitas para emulsões em pH 7 mostraram que com os conjugados formados após 24 h de reação, a distribuição da proteína na interface foi mais homogênea. No pH 3,5, não houve efeito de carga e a estabilidade das emulsões foi atribuída à presença dos polissacarídeos que promoveram maior viscosidade da fase contínua e maior espessura da camada interfacial, provocando repulsão estérica entre as gotas. Neste pH, os conjugados formados após 24 h de reação melhoraram a estabilidade das emulsões. Nas análises reológicas observaram-se maiores valores de viscosidade aparente nas emulsões com o maior conteúdo de polissacarídeo (razão 0,3), e este valor foi ainda maior em pH 7. Dessa forma, os módulos complexos (G*) das emulsões também atingiram valores mais altos em pH neutro, confirmando a melhor estruturação das emulsões. Quanto à reologia interfacial, o módulo complexo de viscoelasticidade (E*) da interface óleo ¿ solução de biopolímero na razão 0,3 apresentou valor elevado e pouca variação ao longo do tempo, caracterizando uma interface mais elástica e estável, com estrutura mais rígida devido ao polissacarídeo. Com estes resultados, pode-se afirmar que os conjugados formados em tempo iniciais de reação e compostos por maior quantidade de goma jataí melhoraram a estabilidade das emulsões devido ao efeito estérico do polissacarídeo que foi ainda mais pronunciado em pH ácido / Abstract: The emulsions are naturally present in some foods or they are applied in food products due to their technological properties. However, emulsions are termodynamically unstable and their phases tend to separate with time. The stability of emulsions can be improved by using emulsifiers and stabilizers. In this work it was studied the combined action of two natural biopolymers to improve the kinetic stability of oil-in-water emulsions (O/W). Conjugates composed by sodium caseinate and locust bean gum were produced by Maillard reaction at different protein/polysaccharide ratio and reaction time to obtain a conjugate with better stabilizing action than individual biopolymers in emulsions prepared at two pH conditions. The conjugates formation was confirmed by polyacrylamide gel electrophoresis analysis that revealed the presence of compounds with high molecular weight after the reaction. In general, the emulsions at pH 7 were more stable than at pH 3.5. At neutral pH, as the protein was further from its isoelectric point, it was more soluble and negatively charged, resulting in the electrostatic repulsion between the droplets. The confocal microscopy analysis showed that emulsions at pH 7 composed by conjugates formed after 24 h of reaction, presented more homogeneous protein distribution at the interface. At pH 3.5, there was no electrical charge effect on the emulsion and the stability was attributed to the presence of polysaccharides, which promoted higher viscosity of the continuous phase and increased the interfacial layer thickness, resulting in steric repulsion between the droplets. Regarding the rheological behavior, it was observed higher values of apparent viscosity in emulsions with highest polysaccharide content (ratio 0.3), and these values were higher at pH 7 than at pH 3.5. Moreover, the complex moduli (G *) values of the emulsions were also higher at neutral pH, confirming better structured emulsions. In relation to the interfacial rheology, the viscoelastic complex moduli (E *) on the oil ¿ biopolymer solution interface at 0.3 ratio presented higher value with low variation with time, characterizing more elastic and stable interface composed by rigid structure due to the polysaccharide. Based on these results, it was observed that the conjugates formed at early reaction time and composed by large amount of locust bean gum improved the emulsions stability due to the steric effect of the polysaccharide which was more pronounced at acid pH / Mestrado / Engenharia de Alimentos / Mestra em Engenharia de Alimentos

Orientador: Rosiane Lopes da Cunha / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-19T15:44:48Z (GMT). No. of bitstreams: 1 Perrechil_FabianadeAssis_D.pdf: 11335528 bytes, checksum: 434b9b3fbcb285d59ca3a70da948903d (MD5) Previous issue date: 2012 / Resumo: A microencapsulação é uma técnica que vem sendo amplamente estudada para a proteção de compostos bioativos e controle de sua liberação. Neste contexto, o objetivo geral deste trabalho foi produzir micropartículas através da extrusão de emulsões estabilizadas por biopolímeros (caseinato de sódio e ?-carragena) em solução de cloreto de potássio para a encapsulação de compostos hidrofóbicos. Na primeira parte deste estudo, o processo de extrusão em um atomizador foi estudado através da produção de microgéis a partir de soluções aquosas de caseinato de sódio (Na-CN) e ?-carragena. Os efeitos da vazão de alimentação, vazão de ar comprimido no bico atomizador, viscosidade e tensão superficial das soluções foram avaliados experimentalmente e através da análise de parâmetros adimensionais. Os resultados mostraram que os menores microgéis foram obtidos com a menor vazão de alimentação, menor viscosidade da solução biopolimérica e maior vazão de ar comprimido. No entanto, a esfericidade dos microgéis foi principalmente influenciada pela tensão superficial das soluções. Na segunda etapa do trabalho, emulsões óleo-água (O/A) multicamadas estabilizadas por caseinato de sódio e ?-carragena foram estudadas com o intuito de determinar as condições de maior estabilidade em pH 7 e 3,5. Em pH 7, o fenômeno de floculação por depleção ocorreu em elevada concentração de ?-carragena, enquanto que em pH 3,5 foi observada a floculação por ponte (bridging flocculation) em menores concentrações de polissacarídeo. Emulsões estáveis foram produzidas na maior concentração de polissacarídeo (1% m/v) em ambos os valores de pH (7 e 3,5) devido ao aumento da viscosidade da fase contínua. Na terceira parte do estudo, microesferas com potencial para encapsulação de compostos hidrofóbicos foram produzidas a partir da gelificação iônica das emulsões multicamadas e avaliadas quanto à estabilidade em diferentes meios. As microesferas produzidas em pH 3,5 foram mais estáveis do que aquelas preparadas em pH 7, sendo que ambas foram altamente estáveis quando dispersas em soluções de cloreto de potássio com concentrações superiores a 0,75% (m/v). Na última etapa do trabalho foi avaliado um exemplo de aplicação das microesferas para encapsulação de triptofano. Nesta etapa, as propriedades reológicas de suspensões de microgéis também foram estudadas com o intuito de verificar a sua influência na textura dos produtos. A eficiência de encapsulação do triptofano nas microesferas foi baixa (~30%), o que pode ser explicado pelo elevado tamanho dos poros do gel que não impediu a difusão desse composto de baixa massa molecular. No entanto, a liberação do bioativo foi bastante baixa quando as micropartículas foram diluídas em solução aquosa. Além disso, suspensões de microesferas com menores diâmetros e formatos mais esféricos apresentaram pouca influência na textura, mostrando sua potencial aplicação em produtos contendo elevada quantidade de água / Abstract: Microencapsulation is a technique widely used for the protection of bioactive compounds and for controlling their release. In this context, the general purpose of this work was to produce microbeads through the extrusion of biopolymer-stabilized emulsions (sodium caseinate and ?-carrageenan) in a potassium chloride solution, aiming the encapsulation of hydrophobic compounds. In the first part of this work, the extrusion process was studied in an atomizer, producing microgels from aqueous solution of sodium caseinate (Na-CN) and ?-carrageenan. The effect of feed flow rate and compressed air flow rate in the atomizer nozzle, viscosity and surface tension of solutions were evaluated experimentally and through the analysis of dimensionless parameters. The results showed that smaller microgels were produced using lower feed flow rate, lower viscosity and higher compressed air flow rate. Nevertheless, the sphericity of microgels was mainly influenced by the surface tension of solutions. In the second step of this work, oil-in-water (O/W) multilayered emulsions stabilized by sodium caseinate and ?-carrageenan were studied in order to determine the conditions of higher stability at pH 7 and 3.5. At pH 7, depletion flocculation occurred at high ?-carrageenan concentrations, while at pH 3.5, bridging flocculation was observed at lower polysaccharide concentrations. Stable emulsions were produced in the highest polysaccharide concentration (1% w/v) in both pH values (7 and 3.5) due to the increase of viscosity of the continuous phase. In the third part of this study, microbeads potentially useful for encapsulation of hydrophobic compounds were produced by ionic gelation of multilayered emulsions and evaluated in relation to stability in different media. The microbeads produced at pH 3.5 were more stable than those prepared at pH 7 and both were highly stable when dispersed in solutions with more than 0.75% (w/v) potassium chloride. In the last step of this study, an example of microbead application for encapsulating tryptophan was evaluated. In this step, the rheological properties of suspensions of microgels were also studied in order to verify their influence on the texture of products. The encapsulation efficiency of tryptophan in the microbeads was low (~30%), which was attributed to the large pore size of the gel matrix that could not hinder the diffusion of this low molecular weight compound. However, the release of bioactive was very low when the particles were diluted in aqueous solution. Moreover, suspensions of microbeads with smaller diameters and more spherical shape showed little influence on the texture, exhibiting their potential application in products with high water content / Doutorado / Engenharia de Alimentos / Doutor em Engenharia de Alimentos

Orientador : Rosiane Lopes da Cunha / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T02:33:04Z (GMT). No. of bitstreams: 1 Takeuchi_KatiuchiaPereira_M.pdf: 1779769 bytes, checksum: 68792b5cd7f6aee9eaab0bdb1c4181d4 (MD5) Previous issue date: 2003 / Resumo: Neste trabalho, as interações entre as proteínas do leite-carragena-sacarose em meio aquoso foram estudadas em sistemas mantidos em pH 6,7 e submetidos a tratamento térmico de 70ºC por 30 minutos. Estas interações foram estudadas através da avaliação do comportamento reológico em cisalhamento sob regime oscilatório da mistura dos biopolímeros e sacarose, durante e após a gelificação. As propriedades mecânicas dos produtos gelificados foram analisadas em ensaios a altas deformações sob compressão uniaxial, possibilitando um estudo das características de rigidez e elasticidade dos géis formados. As propriedades reológicas foram fortemente influenciadas pela carragena, que mostrou interação com as proteínas do leite e favoreceu a característica elástica dos sistemas. O isolado protéico de soro (IPS) promoveu o fortalecimento da rede, enquanto que o caseinato de sódio pareceu diminuir a rigidez da rede do gel, pois beneficiou a característica viscosa dos sistemas. A sacarose favoreceu a interação do IPS com a carragena levando à formação de uma rede mais interconectada, portanto mais elástica e resistente à ruptura. As interações entre as proteínas do leite-carragena-sacarose também foram avaliadas através da medida do estado da água nestes sistemas por meio de calorimetria diferencial de varredura, com a determinação da fração de água livre e não-congelável e a temperatura de início de fusão. A quantidade de água não-congelável e a temperatura de início de fusão foram fortemente influenciadas pela sacarose, provavelmente pelo favorecimento de interações entre as proteínas e destas com a água. O tratamento térmico (70ºC por 30 min) permitiu a interação das proteínas do soro com as frações hidrofílicas da caseína e sua interação com a carragena. As interações que ocorreram entre as proteínas do leite após o tratamento térmico, relacionadas à agregação intermolecular ou intramolecular, foram analisadas através de eletroforese de gel de poliacrilamida. Essa análise permitiu verificar que as concentrações das proteínas presentes no sistema influenciam na quantidade das unidades livres em solução, possibilitando a interação delas com os outros componentes do sistema, como a água e a carragena / Abstract: Interactions among milk proteins-carrageenan-sucrose in aqueous medium were studied in systems at pH 6.7 and submitted to thermal treatment at 70ºC for 30 min. These interactions were studied by evaluation of rheological behavior under oscillatory and steady shear of biopolymers mixture and sucrose during and after gelation. The mechanical properties of gelified products were determined in studies under uniaxial compression at high deformations, allowing a study of the characteristics of rigidity and elasticity of formed gels. The rheological properties were strongly influenced by carrageenan, wich showed interactions with milk proteins and favored the elasticity characteristic of the systems. Whey protein isolate (WPI) favored the formation of a more strength network, while sodium caseinate seemed decrease the rigidity of the gel network, since improved the viscous characteristic of the systems. Sucrose enhanced the interaction between WPI and carrageenan causing the formation of a more elastic network and resistant to the rupture. The interactions among milk proteins-carrageenan-sucrose were evaluated by quantification of state of water in these systems using a differential scanning calorimetry, with determination of free and unfreezable water fractions and the melting temperature onset. The unfreezable water (UFW) and temperature onset were strongly influenced by sucrose, probably by the enhancement of interactions protein-protein and protein-water. The thermal treatment (70ºC for 30 min) supported the interactions between the whey protein with the hydrophilic fractions of casein and their interactions with carrageenan. The interactions between milk proteins after thermal treatment were analysed by polyacrylamide gel electrophoresis related to intermolecular and intramolecular aggregation. This analysis allowed to verify that the protein concentration of the system had an effect on the amount of the free units in solution, making possible the interactions of them with the other systems components, as water and carrageenan / Mestrado / Mestre em Engenharia de Alimentos