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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

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Le caroubier est considéré comme l'un des arbres fruitiers et forestiers qui présente le plus grand potentiel de valorisation puisque toutes les parties de cette plante sont utilisables dans plusieurs applications industriels. Le caroubier est cultivé dans plusieurs régions du Liban mais peu d'études sont disponibles sur les voies de valorisation et sur les propriétés fonctionnelles et structurales des graines et des gousses. Ainsi, dans le cadre d'une démarche qui vise à promouvoir et contribuer à une meilleure valorisation et gestion de cette ressource renouvelable, nous avons entrepris dans cette thèse des travaux consacrés à la caractérisation et à l'évaluation de la valeur nutritive et fonctionnelle des gousses de caroube issues de plusieurs régions libanaise. Ces travaux ont porté notamment sur la caractérisation morphologique et physico-chimique des gousses et sur la purification des gommes extraits des graines. Ces gommes ont fait l'objet d'une étude approfondie portant sur leur comportement rhéologique et la relation entre ce comportement, la variété et le lieu géographique. Nous avons aussi déterminé les isothermes de sorption de ces gommes pour prédire les conditions idéales de leur conservation. Les résultats obtenus à l'issue de cette étude ont démontré clairement la présence des corrélations morphologie, composition chimique et coordonnées géographiques de différents cultivars étudiés. De même, les études structurales et rhéologiques ont montré des différences significatives entre les gommes purifiées. Cette différence semble être liée à une variation du rapport galactose/mannose et de la masse molaire observée selon les variétés. Par ailleurs, les études des isothermes de sorption ont permis de fournir des informations complémentaires sur leurs hygroscopicités et par conséquence sur les conditions idéales de leur conservation / The carob plant is considered as one of the fruit and forester tree that has the greatest potential of valorization since all the parts of this plant can be used in several food and cosmetic applications. The carob is cultivated in several areas of lebanon but few studies are available on the ways of valorization and the functional and structural properties of the different fractions of this tree (seeds and pods). Thus, in view to develop a strategy aims to promote and contribute to a better valorization and management of this renewable resource, we undertook in this thesis of work devoted to the characterization and the evaluation of nutritive and functional properties of the carob pods resulting from several lebanese areas. This work focused particularly on the morphological and physicochemical characterization of the pods and the purified fraction of gum. These gums were the subject of a thorough study relating to their rheological behavior and the relation between this behavior, the variety and the geographical localization of the studied varieties. We also determined the isotherms of sorption of these gums to predict the ideal conditions of their conservation. The obtained results clearly showed the presence of the correlations between morphology, chemical composition and geographical localization of the different studied cultivars. In the same way, the structural and rheological studies showed significant differences between purified gums. This difference seems to be related to a variation of the galactose /mannose ratio and molar mass according to the varieties. These interesting rheological properties open the carob gums a new niches of valorization with added values. In addition, the studies of the isotherms of sorption provided additional information on their hygroscopicities and by consequence on the ideal conditions of their conservation

Aspergillus fumigatus produces enzymes required for the hydrolysis of galactomannans like locust bean gum. Among these enzymes endo-beta-1,4 mannanase is also produced at high levels. However, the fungus is not safe for use in the food industry. Therefore, the gene encoding endo-beta-1,4-mannanase of A. fumigatus IMI 385708 was previously cloned in our laboratory into Aspergillus sojae ATCC11906 which is a safe microorganism for use in food applications. Altogether eight transformants were obtained. It was shown that some of these transformants overproduce the enzyme because of expression under the control of glyceraldehyde-3-phosphate dehydrogenase promoter and fusion to the glucoamylase signal and pro-peptide coding region of Aspergillus niger. In this study, mannanase production of these transformants was compared with A. fumigatus and A. sojae transformant AsT1 showed c. 12 fold increase with the maximum activity of 352 U/ml. The effects of initial medium pH and number of spores on activity were investigated and maximum activity was achieved at pH 7.0 and the number of spores was found as 3.6 &times / 106. Optimization of the growth conditions for maximum mannanase production in shake flasks by using the best mannanase producing transformant AsT1 was carried out by using Box-Behnken design under Response Surface Methodology. The highest beta-mannanase activity on the fourth day of cultivation at 30 &ordm / C was obtained as 363 U/ml in the optimized medium containing 7% sugar beet molasses, 0.43% NH4NO3, 0.1% K2HPO4, 0.05% MgSO4 as the weight/volume percentage at 207 rpm. On sixth day of cultivation under the optimized conditions, the highest mannanase activity was achieved as 482 U/ml which is 1.4 fold of 352 U/ml activity found on glucose medium previously. After 48 h of LBG hydrolysis by 40 U of mannanase, mannotriose, 61-galactosyl-beta-D-mannotriose and 63,64-di-alpha-galactosyl-beta-1,4-mannopentaose were found as the main products via HPLC analysis.

Orientador: Caroline Joy Steel / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-06T15:43:12Z (GMT). No. of bitstreams: 1 Almeida_EvelineLopes_M.pdf: 15471832 bytes, checksum: b43c4088e42981acaea0df1073c7d74c (MD5) Previous issue date: 2006 / Resumo: O objetivo deste trabalho foi estudar o efeito da adição de diferentes fontes de fibra alimentar em pão convencional e em pão pré-assado congelado. Um delineamento composto central rotacional (DCCR) foi utilizado, com as porcentagens das diferentes fontes de fibra alimentar - farelo de trigo, amido resistente e locust bean gum (LBG) - sendo as variáveis independentes. O delineamento incluiu dezoito ensaios: oito pontos fatoriais, seis pontos axiais e quatro repetições do ponto central. Os resultados foram analisados pela Metodologia de Superfície de Resposta. Os níveis de farelo de trigo, amido resistente e LBG usados foram, respectivamente: 0-20%, 0-20% e 0-3% (base farinha). As variáveis dependentes foram parâmetros farinográficos das combinações de farinha de trigo e fontes de fibra, parâmetros do processo de panificação (tempo de mistura rápida e tempo de fermentação) e características de qualidade dos pães (volume específico, cor instrumental da crosta e do miolo, aceitação sensorial, vida de prateleira avaliada através da umidade do miolo e dureza dos pães após um, quatro e sete dias do forneamento). O efeito do período de estocagem congelada (0, 32 ou 62 dias) foi avaliado através da submissão da média dos dados das características de qualidade dos pães dos dezoito ensaios do planejamento à análise de variância e teste de Tukey. Os resultados mostraram que as fontes de fibra alimentar modificaram a absorção de água e as propriedades de mistura da farinha de trigo, interferiram no tempo de mistura rápida do processo e nas características tecnológicas do pão, como volume, cor, umidade e dureza. No entanto, notou-se que as modificações tecnológicas não inviabilizaram os produtos, uma vez que eles foram bem aceitos sensorialmente e apresentaram uma alta intenção de compra pelos provadores. Verificou-se que o aumento do tempo de estocagem congelada, de 32 para 62 dias, não teve grande interferência na maioria das características dos pães analisados. Concluiu-se que foi possível a produção de pães convencionais e pães pré-assados congelados com fibras que atendem à legislação brasileira para fins de rotulagem nutricional de fibra alimentar (considerados fonte e/ou alto teor de fibras), com parâmetros tecnológicos e sensoriais que os permitem ser considerados produtos de boa qualidade / Abstract: The aim of this work was to study the effect of adding different dietary fiber sources to conventional bread and to frozen part-baked bread. A central composite rotational design (CCRD) was used, with the percentages of the different dietary fiber sources ¿ wheat bran, resistant starch and locust bean gum (LBG) ¿ being the independent variables. The design included eighteen trials: eight factorial points, six axial points and four repetitions of the central point. Results were analyzed using the Response Surface Methodology. The levels of wheat bran, resistant starch and LBG used were, respectively: 0-20%, 0-20% and 0-3% (flour basis). The dependent variables were farinographic parameters of the combinations of wheat flour and dietary fiber sources, baking process parameters (rapid mixing time and proofing time) and bread quality characteristics (specific volume, crust and crumb instrumental color, sensory acceptance, shelf-life evaluated through crumb moisture and bread hardness after one, four and seven days from baking). The effect of the frozen storage period (0, 32 or 62 days) was evaluated by the submission of the average values of the bread quality characteristics of the eighteen trials of the experimental design to Analysis of Variance and the Tukey test. The results showed that the dietary fiber sources modified the water absorption and the mixing properties of the wheat flour, interfered in the rapid mixing time and in the technological characteristics of bread, such as volume, color, moisture and hardness. Nevertheless, it was shown that the technological modifications did make the products unfeasible, as they had a good sensory acceptance and a high buying intention by the panelists. It was observed that the increase of frozen storage time, from 32 to 62 days, did not greatly affect most of the bread characteristics analyzed. It was concluded that it was possible to produce conventional and frozen part-baked breads with fiber that attend the Brazilian legislation regarding nutritional labeling claims related to dietary fiber (breads that can be considered sources and/or high fiber content), having technological and sensory parameters that permit them to be considered good quality products / Mestrado / Mestre em Tecnologia de Alimentos

La présente thèse traite, au travers d’une analyse fondamentale et expérimentale, l’effet de texturation par détente instantanée contrôlée (DIC) sur les phénomènes de transfert au cours des processus de séchage, d’extraction mécanique et de comportement rhéologique. Les produits concernés ont été les graines de caroube (gomme et germe) et deux variétés de graines de tournesol (linoléique et oléique). La texturation DIC permet d’agir sur la cinétique de séchage par flux d’air ce qui conduit à une intensification des processus de séchage par flux d’air tout en assurant une bonne préservation de la qualité nutritionnelle du produit fini. L’étude expérimentale a été couplée à une analyse phénoménologique de la cinétique à travers une modélisation de type CWD (coupled Washing/Diffusion). Cette dernière étude conduit à une évaluation de l’impact de la texturation sur la diffusivité effective Deff et l’accessibilité initiale δWs. D’autre part, l’étude expérimentale en vue de l’optimisation de l’opération a été réalisée à travers la méthode des plans d’expériences. La modification des paramètres opératoires fonctionnels de la DIC, à savoir la pression absolue de vapeur d’eau saturée sèche (P), et le temps de traitement thermique (t), ainsi que le nombre des cycles (c) sur l’ensemble des performances de l’opération a été établie sur le comportement rhéologique de la gomme de caroube. Une deuxième partie de la thèse a été consacrée à l’étude fondamentale et expérimentale des procédés d’extraction d’huile de tournesol des deux variétés de graines linoléiques et oléiques. Le traitement thermomécanique par détente instantanée contrôlée (DIC) permet, à travers une modification contrôlée de la structure de la matière première, d’agir sur l’extraction mécanique par presse à froid des huiles de tournesol, ainsi que sur l’extraction par solvant de l’huile à partir du tourteau résiduel. Un complément à cette opération a consisté en l’extraction par solvant (n-hexane) opérée sur l’ensemble des graines de tournesol. La texturation DIC a conduit à une grande augmentation du rendement en huile pour les variétés linoléique et oléique. La préservation de la qualité de l’huile et du tourteau prouve l’adéquation de la DIC avec l’absence pratique de la dégradation chimique. Notre étude a également concerné la définition d’un nouveau procédé de désodorisation. Il s’agit de l’utilisation de l’Autovaporisation Multi-Flash MFA sur le raffinage de l’huile de tournesol. Cette technologie innovante de désodorisation se distingue par son faible niveau de température assurant ainsi une sévérité nettement inférieure à celle des méthodes conventionnelles à haute température. / This thesis deals with a fundamental and experimental analysis of the effect of instant controlled pressure drop (DIC) on the transfer phenomena and rheological behavior, which occurs during the drying process and mechanical and solvent extraction. The products concerned were carob seeds (gum and germ) and two varieties of sunflower seeds (linoleic and oleic). DIC texturing makes it possible to greatly modify the drying kinetics, leading to an effective intensification of the drying processes while maintaining a good preservation of the nutritional quality of the finished product. The experimental study was coupled with a phenomenological kinetic model using the CWD (coupled Washing/Diffusion). This study leads to evaluate the impact of texturing on the effective diffusivity Deff and the initial accessibility δWs. On the other hand, the experimental study for the optimization of the operation was carried out through an adequate experimental design method. The impact of the DIC processing parameters, namely the absolute pressure of saturated dry water vapor (P), and the heat treatment time (t), as well as the number of cycles (c) was established on the rheological behavior of the carob bean gum. A second part of our work was devoted to the theoretical and experimental study of sunflower oil extraction processes of the two types of linoleic and oleic seeds. By acting as a controlled modification of the raw material, (DIC) texturing allowed increasing the yield of sunflower oil by both cold pressing and solvent extraction from the residual cake. DIC texturing has led to a large increase in oil yield for both linoleic and oleic varieties. The preservation of the quality of oil demonstrates that DIC was perfectly adequate with a perfect absence of chemical degradation. Our study also involved the definition of a new deodorization process. This is the use of the Multi-Flash Autovaporization MFA on the refining of sunflower oil. This innovative deodorization technology is characterized by its low temperature level, thus ensuring a much lower severity than conventional high temperature methods.