Orientador: Hilary Castle de Menezes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T09:18:53Z (GMT). No. of bitstreams: 1 Lopes_AlessandraSantos_D.pdf: 3488044 bytes, checksum: f87fb3e276cf6bc8933b4387bcc1c4bd (MD5) Previous issue date: 2005 / Resumo: A pitanga (Eugenia uniflora L.) é um fruto nativo das regiões Sul e Sudeste do Brasil, e muito pouco investigado cientificamente. Graças às suas qualidades vitamínicas e sensoriais, a pitanga foi o principal objeto de estudo deste trabalho de tese. A acerola, excelente fonte de vitamina C, também foi abordada neste trabalho. O estudo da acerola consistiu basicamente na avaliação da polpa como matéria-prima para a indústria de néctares mistos, objetivando o enriquecimento em vitamina C do néctar de pitanga. Em relação aos processos tecnológicos aplicados às polpas e néctares, foram estudados os processos de extração de polpa e os métodos de conservação tradicionais: congelamento e pasteurização térmica. Como conseqüência lógica, também foi avaliada a estabilidade dos produtos processados com o intuito de determinar a ocorrência de alterações físicas, físico-químicas e sensoriais. O estudo do processo de extração de polpa (Capítulo 2) foi realizado em dois diferentes tipos de despolpadores: despolpador de escovas inclinado e despolpador de pás horizontal. Para os frutos de pitanga, os equipamentos de escovas e pás apresentaram rendimentos de polpa de 58,47±3,92% e 46,61±1,80%, respectivamente. A polpa obtida no despolpador de pás apresentou uma diferença total de cor (.E*) em relação aos parâmetros de cor L*, a* e b* dos frutos in natura, significativamente superior (p¡Ü0,05) a polpa processada no despolpador de escovas. Por isso, o despolpador de escovas se mostrou mais eficiente que o despolpador de pás para obtenção de polpa de pitanga, devido ao maior rendimento e menor .E*. No estudo de estabilidade da polpa de pitanga preservada por congelamento (Capítulo 3) durante 90 dias, os resultados obtidos mostraram que a reação cinética da degradação dos parâmetros de cor a* e diferença total de cor (.E*) se ajustaram aos modelos cinéticos de 1a ordem e zero ordem, respectivamente. Ao mesmo tempo, houve uma forte queda na aceitabilidade sensorial e na atitude positiva de compra do néctar formulado com a polpa de pitanga armazenada por 90 dias a ¿18oC, devido às significativas mudanças na qualidade física do néctar formulado com a polpa de pitanga congelada. No estudo de pasteurização térmica da polpa de pitanga (Capítulo 4) foi empregado um planejamento composto central (22), onde as variáveis independentes foram os parâmetros tempo e temperatura de processamento, e as variáveis dependentes foram cor instrumental (a*, b* e .E*) e atividade enzimática. O binômio tempo-temperatura de pasteurização térmica mais adequado para a conservação da polpa de pitanga foi de 59 a 68s a 90oC, considerando as mínimas alterações de cor instrumental e a inativação das enzimas presentes. O estudo do comportamento reológico da polpa de pitanga (Capítulo 5) na faixa de temperatura de pasteurização de 83 a 97oC determinou que a polpa de pitanga apresentou comportamento pseudoplástico e o modelo de Herschel-Bulkley foi considerado o mais adequado. Os índices de comportamento de fluido (n), variaram na faixa de 0,448 a 0,627. O efeito da temperatura sobre a viscosidade aparente pôde ser descrito pela equação análoga à de Arrenhius, observando-se a diminuição da viscosidade aparente com o aumento da temperatura. A energia de ativação do escoamento viscoso da polpa de pitanga, para a taxa de deformação de 100s-1, foi de 2,947 Kcal.gmol-1. No estudo de avaliação dos processos de despolpamento e estabilidade da polpa de acerola (Capítulo 6) preservada por congelamento durante 180 dias, foi determinado que o despolpador mais adequado para a extração da polpa de acerola foi o extrator de escovas, pois apresentou um maior rendimento (62,83%) e menor alteração da cor instrumental. No estudo de estabilidade da polpa de acerola, obtida no extrator de escovas, foi verificado que a mesma apresentou ótima estabilidade física, físico-química e sensorial até o final do experimento, exceto para o parâmetro de cor instrumental .E* (diferença total de cor), que variou significativamente (p¡Ü0,05) durante o período de estocagem da polpa de acerola. Paralelamente, foi observado um decréscimo significativo estatisticamente (p¡Ü0,05) no teor de antocianinas totais (16,23%). De acordo com a análise sensorial do atributo cor, a variação no teor de antocianinas totais não comprometeu significativamente (p>0,05) a aceitabilidade da polpa de acerola estocada por 180 dias a ¿18oC. No estudo de formulação e pasteurização térmica de néctar misto através da metodologia de superfície de resposta (Capítulo 7), foi verificada a maior aceitabilidade das formulações com maiores proporções de polpa de pitanga (26,4% a 32,9%). Na etapa de pasteurização do néctar misto foi determinada que na faixa de tempo entre 39s a 60s em temperaturas que variam de 83oC a 85oC, os néctares mistos pasteurizados de acerola e pitanga apresentaram as menores alterações sensoriais, e conseqüentemente maior a aceitabilidade / Abstract: Pitanga (Eugenia uniflora L.) is a native fruit of the southern and south-eastern regions of Brazil, little studied scientifically. Pitanga was the main objective of this thesis due to its vitamin content and sensory qualities. West Indian cherry, an excellent vitamin C source, was also included in the study. The research on West Indian cherry was basically the evaluation of its pulp as a raw material for the mixed nectar industry, aiming to enrich the pitanga nectar with respect to vitamin C. The technological processes applied to the pulps were the extraction processes and the traditional methods of preservation: freezing and heat pasteurisation. As a logical sequence, the stability of the processed pulps was also evaluated, checking for physical, physicochemical and sensory alterations. The extraction process (Chapter 2) was carried out with two types of pulper: an inclined brush pulper and a horizontal blade pulper. For pitanga, the brush and blade pulpers gave pulp yields of 58.47±3.92% and 46.61±1.80% respectively and the pulp obtained using the blade pulper presented a significantly greater (p¡Ü0.05) total difference in colour (.E*) with respect to the colour parameters L*, a* and b* as compared to the in nature fruits, than that obtained using the brush pulper. Thus the brush pulper was shown to be more efficient due to a greater yield and smaller .E*. The study of pitanga pulp stability during 90 days of frozen storage (Chapter 3) showed that the degradation kinetics of the parameters a* and .E* fitted the 1st and zero order kinetic models respectively. At the same time there was a distinct loss in sensory acceptance and in the positive attitude to buying the nectar formulated with the pitanga pulp stored for 90 days at ¿18ºC, due to significant changes in the nectar formulated with this pulp. A 2² central composite experimental design was used in the study of the heat pasteurisation of pitanga pulp (Chapter 4), the independent variables being the process parameters of time and temperature and the dependent variables, the instrumental colour (a*, b* and .E*) and enzyme activity. The most adequate time-temperature binomial for the preservation of pitanga pulp by heat pasteurisation was from 59 to 68s at 90ºC, when considering minimal alterations in instrumental colour and inactivation of the enzymes. A study of the rheological behaviour of the pitanga pulp (Chapter 5) in the pasteurisation temperature range (83 to 97ºC) showed that it presented pseudoplastic behaviour, adjusting best to the Herschel-Bulkley model. The fluid behaviour index (ç) varied from 0.448 to 0.627. The effect of temperature on the apparent viscosity could be described by the Arrenhius analogical equation, the apparent viscosity decreasing with increase in temperature. The activation energy for viscous flow of the pitanga pulp was 1.947 Kcal.gmol-1 for a deformation rate of 100s-1. In the study on extraction procedures and stability of West Indian cherry pulp (Chapter 6) stored frozen for 180 days, the brush pulper was shown to be more adequate, giving a higher yield (62.83%) and lower alteration in instrumental colour. The West Indian cherry pulp extracted with the brush pulper showed excellent physical, physicochemical and sensory stability up to the end of the experiment, with the exception of the parameter .E*, which varied significantly during frozen storage. In parallel, a statistically significant (p¡Ü0.05) decrease in total anthocyanins was observed. According to the sensory analysis of the attribute colour, the variation in anthocyanin content did not significantly compromise the acceptability of the West Indian cherry pulp after 180 days of storage at ¿18ºC. In the study on the formulation and heat pasteurisation of the mixed nectar using response surface methodology (Chapter 7), a greater acceptance of the formulations containing higher proportions of pitanga pulp (26.4% and 32.9%) was observed. With respect to heat pasteurisation, temperatures between 83 and 85ºC for 39 to 60s presented the smallest sensory alterations and consequently the greatest acceptability of the mixed pitanga and West Indian cherry nectars / Doutorado / Tecnologia de Alimentos / Doutor em Tecnologia de Alimentos

Lorsque l'allaitement est impossible, du lait maternel pasteurisé (LMP) est préférentiellement administré, en particulier aux nouveau-nés hospitalisés. La pasteurisation de Holder (62,5°, 30 min) est appliquée pour des raisons sanitaires mais pourrait réduire l'absorption des lipides via l'inactivation des lipases endogènes du lait. L’homogénéisation du LMP pourrait contrer cet effet négatif en augmentant la surface disponible pour l’adsorption des enzymes. L’objectif de cette thèse était d’étudier l’impact de la pasteurisation de Holder et de l’homogénéisation par ultrasons sur la digestion du LM chez le nouveau-né. Un modèle de digestion in vitro a été mis en place pour évaluer la digestion gastro-intestinale de LM cru (LMC) vs. LMP aux stades « nouveau-né à terme » ou « prématuré ». Une étude clinique a été menée chez des nouveau-nés prématurés pour comparer la digestion gastrique de (A) LMC vs. LMP et (B) LMP vs. LM pasteurisé et homogénéisé (LMPH).La pasteurisation et l’homogénéisation ont modifié la structure initiale du LM, ses cinétiques digestives et sa désintégration structurale. In vitro, la pasteurisation a réduit la lipolyse gastrique au stade à terme, alors qu’aucun impact n'a été observé au stade prématuré. La lipolyse intestinale, in vitro, a été réduite. In vivo, la pasteurisation a accélérée la protéolyse gastrique de la lactoferrine et a réduit celle de l’a-lactalbumine. L'homogénéisation a accéléré la lipolyse et la protéolyse de l'albumine sérique. Concernant les conditions physiologiques, l’activité lipolytique postprandiale était augmentée après adm / When breastfeeding is not possible, pasteurized human milk (PHM) from milk banks is preferentially administered, especially for vulnerable hospitalized newborns. Holder pasteurization (62.5°, 30 min) is applied for sanitary reasons but may reduce fat absorption through inactivation of milk endogenous lipases. This could be counteracted by homogenization of PHM through an increase of the specific surface available for enzyme adsorption. The objective of this thesis was to study the impact of Holder pasteurization and ultrasonic homogenization on the digestion of HM in the newborn. An in vitro dynamic model was used to evaluate the gastrointestinal digestion of raw HM (RHM) vs. PHM at preterm and term stages. A clinical trial was conducted on hospitalized preterm newborns for comparing the gastric digestion of (A) RHM vs. PHM and (B) PHM vs. pasteurized-homogenized HM (PHHM). Pasteurization and homogenization affected the HM initial structure and its digestive kinetics and structural disWhile gastric lipolysis was reduced after pasteurization in term in vitro study, no impact was observed at the preterm stage. Intestinal lipolysis, in vitro, was reduced by pasteurization. Gastric proteolysis was selectively affected by pasteurization, being, in vivo, faster for lactoferrin and slower for a-lactalbumin. Homogenization increased lipolysis and proteolysis of serum albumin. Some physiological gastric conditions were affected by treatments: RHM had enhanced postprandial lipolytic activity and PHHM had a reduced gastric emptying time. The in vivo data described here may help to i

Le baobab est un arbre qui pousse à l'état sauvage en Afrique et ailleurs dans le monde où le fruit est consommé sous différentes formes. Si l'écologie et la botanique de la plante ont été bien étudiées, il y a peu d'information disponible sur la composition biochimique d'une manière générale et même inexistante chez les espèces malgaches en particulier. Cette étude s'inscrit dans le contexte du développement et de la valorisation des produits locaux en Afrique. Elle a pour objectif principal de mieux caractériser la pulpe des fruits de baobabs issus d'échantillons de diverses provenances de Madagascar et d'Afrique. A cette fin, elle s'est attachée dans un premier temps à caractériser et à quantifier les principaux éléments nutritifs comme les glucides, les acides aminés, les lipides, les polyphénols, la vitamine C, les acides organiques, les éléments minéraux et les arômes. La caractérisation biochimique de la pulpe a révélé une forte acidité titrable (102 meq/100g) et une teneur élevée en acide ascorbique (jusqu'à 312 mg/100g) et en polyphénols de (60,24 à 137,81mg/100g et de 329 à 1705,98 mg/100g) ainsi qu'un potentiel antioxydant très fort et une bonne source de Ca 658 mg/100g.Une évaluation du potentiel de ce fruit pour une valorisation à plus grande échelle à travers une amélioration des procédés de transformation existant en Afrique a été réalisée. L'identification d'une approche de stabilisation et de conservation du nectar par voie conventionnelle (pasteurisation) a été réalisée. Nos résultats ont montré que le nectar est aussi nutritif que les fruits usuels et que sa stabilisation peut se faire par une pasteurisation en utilisant le barème 70°C/10 min. L'analyse sensorielle du nectar après chaque étape de traitement ou de conservation (42 j) n'a pas montré de modification organoleptique du produit quelque soit la température de stockage Deux approches empiriques classiques (modèles d'Arrhenius et de Ball) ont été utilisés pour décrire la cinétique de dégradation thermique de la vitamine C du nectar.Enfin, une étude de faisabilité de l'utilisation de la spectrométrie proche infrarouge pour la caractérisation des origines et pour la détermination des teneurs en constituants biochimiques a été réalisée. Ce travail a permis de montrer qu'il était possible de doser la matière sèche, les protéines, le fructose et le potassium.Une séparation des espèces basée sur l'analyse des spectres semble aussi pouvoir être réalisée via leur appartenance aux sections (brevetubae, longitubae). / Baobab tree is growing wild in Africa and elsewhere in the world. Fruits are consuming in different ways. Plant ecology and botanic are well detailed, but generally few information is available on biochemical composition and even nothing about Malachi species. This study takes place in the development and valorization of African local fruits program. The main objective is to characterize baobab fruit pulp samples coming from both Madagascar and Africa. First, the main nutriments were characterized and quantified, such as, carbohydrates, amino acids, lipids, polyphenols, vitamin C, organic acids, minerals and aroma compounds. Biochemical characterization of the pulp showed high level of total acidity (102 meq/100g), ascorbic acid (till 312 mg/100g), polyphenols (from 60.24 to 137.81mg/100g) and anti oxidant potential.To valorize the fruit at larger scale, evaluation of its potential was realized trough improvements of existing processing techniques in Africa. A conventional approach (pasteurization) was realized to stabilize and store nectar. Data show nectar is as nutritive than fresh fruit with pasteurization schedule at 70°C/10min. Sensory analysis of nectar after each step of process doesn't show organoleptic difference relative to storage temperature. Two classical empirical approaches (Arrhenius and Ball models) were used to describe kinetic of thermal degradation of C vitamin of nectar.At least, Near Infra Red Spectroscopy (NIRS) was tested, to determine geographical origins and levels of biochemical compounds. Dry matter, proteins, fructose and potassium were quantified. Species segregation with NIRS seems possible by means of belonging to brevetubae and longitubae sections.

Orientadores: José Euclides Stipp Paterniani, Franco Giusepe Dedini / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-18T19:44:20Z (GMT). No. of bitstreams: 1 Rodrigues_DanielleGoncalves_M.pdf: 3768506 bytes, checksum: 1229ddc9f91b3c65c3898169d390236d (MD5) Previous issue date: 2011 / Resumo: A elevada incidência de doenças de veiculação hídrica, devido à ausência de um sistema de saneamento suficientemente eficaz, afeta principalmente as populações que vivem em localidades pobres e em zonas rurais. Dessa forma, busca-se desenvolver cada vez mais, meios alternativos e baratos para promover a melhoria da qualidade de vida dessa população. Neste estudo é apresentado um sistema de pasteurização solar da água (SOPAS) visando desinfecção de água para consumo humano, utilizando como insumo um equipamento de aquecedor solar comercial e dois de baixo custo. Realizou-se testes para verificação da inativação de bactérias do grupo coliformes e heterotróficas nos aquecedores utilizados, os quais ficavam expostos por 8 horas ao sol, durante o período de maio de 2009 a novembro de 2010. Para detecção do grupos coliformes, usou-se a técnica do substrato cromogênico e para a heterotróficas o plaqueamento com Plate Agar Conter. De todos os equipamentos estudados, somente o equipamento de aquecedor solar comercial atingiu a temperatura de 60 º C, necessária para promoção da SOPAS, inativando o grupo coliformes. As bactérias heterotróficas não foram inativadas por nenhum dos equipamentos estudados. Para o desenvolvimento desse estudo, utilizou-se ferramentas de metodologia de projeto como: QFD e benchmarking. Isso possibilitou a realizar entrevistas em zonas rurais de modo a se verificar as condições dessas populações e propor medidas para desenvolver um equipamento para promoção da SOPAS de fácil aceitação e de custo acessível baseado nas necessidades reais do público alvo / Abstract: The high incidence of diseases caused by contaminated water, due to lack of an effective sanitation system, affects people who live in undeveloped and rural areas. In this way, the development of alternative and capable solutions improving the people quality life is researched. This research work introduces the water solar pasteurization system (SOPAS), objectiving water disinfection destined to people consumption, analyzing performance between three equipments being commercial solar heater equipment and two low cost equipments. Tests have been carried on to verify the coliform and heterotrophic bacterial group inactivation on used heaters, which have been exposed for 8 hours under sun, though May, 2009 to November, 2010. Coliform group detection has been applied the chromogenic substrate technique and heterotrophic group detection has been applied the Agar Plate Conter plating technique. It is observed among every tested equipments that only commercial solar heater reached temperature of 60°C, which is necessary to promote the (SOPAS), inactivating the coliform groups. Heterotrophic bacteria groups have not been for any tested equipments. This research work has been applied methodological project tools as: QFD and benchmarking. It allowed carrying on interviews in rural areas, in way to verify conditions of these populations and possibility to purpose actions to develop an equipment to promotion the (SOPAS) as easy acceptance and accessible cost based on real necessities of target public / Mestrado / Agua e Solo / Mestre em Engenharia Agrícola

As indústrias têm deixado de produzir o suco de laranja integral pasteurizado em substituição ao suco de laranja reconstituído devido, principalmente, à dificuldade em se produzir esse tipo de suco durante todo o ano com as mesmas características. Esse trabalho objetivou avaliar sensorialmente esses dois tipos de sucos. Sete provadores selecionados e treinados avaliaram a aparência, aroma, sabor e textura de amostras de suco de laranja utilizando a Análise Descritiva Quantitativa (ADQ). O teste de aceitação pelo consumidor foi realizado com cento e um provadores não treinados, utilizando a escala hedônica e um mapa de preferência foi traçado. A ADQ mostrou que houve diferenças significativas (p<0,05) em relação a: cor amarela, concentrado, aroma laranja, aroma de sumo, sabor de laranja, sabor passado, sabor cozido. Entretanto, não houve diferenças significativas (p>0,05) entre as amostras do suco em relação a: aroma cítrico, aroma cozido, aroma doce, sabor sumo, gosto doce, gosto ácido e encorpado. O suco reconstituído apresentou os atributos com maior intensidade para cor amarela, concentrado, aroma de sumo, sabor passado e sabor cozido em relação ao pasteurizado enquanto esse, o aroma e sabor de laranja foram os atributos mais acentuados. O teste de consumidor indicou que os dois sucos tiveram aceitação parecidas situando-se entre os termos hedônicos indiferente e gostei ligeiramente e o resultado do mapa de preferência mostrou baixa aceitação pela grande maioria dos consumidores de suco. Os dados de HPLC não mostraram diferença entre as amostras de suco analisadas. / The industries are allowing to produce the orange juice pasteurized in substitution to the orange juice reconstituted, mainly, the difficulty in producing this type of juice during the year with the same characteristics. This work objectified to evaluate these sensorially two types of juices. Seven selected and trained panelists evaluated the appearance, aroma, flavor and texture of orange juice pasteurized and orange juice reconstituted by Descriptive Quantitative Analysis (QDA). The consumer test and a preference map was done with one-hundred one non-trained panelists through the hedonic test. The QDA showed significant differences (p<0,05) concerning yellow color, concentrate, orange odor, the highest point odor, orange flavor, passed flavor and cooked flavor. However, there was no significant difference (p>0,05) concerning: citric aroma, candy aroma, cooked aroma, supreme flavor, candy taste, acid taste and viscosity. The reconstituted juice presented the attributes with bigger intensity for yellow color, concentrate, the highest point aroma, last flavor and flavor cooked in relation to the pasteurized and this juice, the aroma and flavor of orange had been the more accented attributes. The consumer test indicated that orange juice pasteurized and orange juice reconstituted were acceptance similar placing itself enters the hedonic terms indifferent and liked slightly and the result of the preference map showed low acceptance by majority of the juice consumers. The HPLC data hadn’t shown the difference enter the analyzed juice samples.

Apesar da citricultura brasileira deter a liderança mundial na produção de laranjas e de suco de laranja concentrado congelado (FCOJ, frozen concentrated orange juice), observa-se baixo consumo no mercado interno de frutos e de suco in natura, o preferido pelo consumidor brasileiro. Assim, há grande interesse no desenvolvimento de produtos, técnicas de produção e conservação específica para variedades de laranja. As indústrias que produzem suco de laranja a partir do processamento da fruta in natura, conhecido como suco pasteurizado não proveniente do suco concentrado, Not From Concentrate (NFC), enfrentam sérios problemas tecnológicos. As frutas apresentam variabilidade química e sensorial devido às características intrínsecas, podendo variar o sabor e aroma devido às diferentes variedades disponíveis ao longo do ano. O objetivo do presente trabalho foi otimizar o processo da radiação gama em suco de laranja, escolhendo a melhor dose, a fim de reduzir a contagem microbiana e não comprometer as características sensoriais e físico-químicas do suco. Definidas as doses, o objetivo foi avaliar as características microbiológicas, físico-químicas e sensoriais do suco de laranja proveniente de três variedades cítricas, submetido aos processos de pasteurização e irradiação e desenvolver uma terminologia descritiva e o perfil sensorial de suco de laranja. As amostras foram avaliadas por uma equipe treinada de nove provadores e avaliadas quanto à aceitação, com escala hedônica de sete pontos por cinquenta provadores. Tendo em vista os resultados obtidos, a radiação gama e a pasteurização contribuíram para a redução das contagens microbiológicas. No entanto, sensorialmente, os tratamentos com 4,5 e 6,0 kGy foram considerados abaixo do limite de aceitabilidade, quanto ao sabor e à impressão global. As doses estudadas mostraram reduzido impacto sobre as características físico-químicas, independente das variedades cítricas. O tratamento com 3,0 kGy resultou em suco com aroma e sabor acentuado de remédio e cozido, que provavelmente terão influência negativa na aceitabilidade do produto / The Brazilian citrus is the global leader in production of oranges and frozen concentrated orange juice (FCOJ) there is low domestic consumption of fruits and fresh juice, preferred by brazilian consumers. Thus, there is a great interest by development of products, processes and specific conservation to the cultivation of citrus varieties for the juice\'s production. The industries produce orange juice from the fresh fruit processing, known as pasteurized juice not from concentrate juice (NFC), have serious technological problems. The fruits have chemical and sensory variability due to intrinsic characteristics and can vary the flavor and smell of orange juice because the different varieties available throughout the year. The aim of this study was to optimize the process of gamma radiation in orange juice, picking the best dosage in order to reduce microbiological count and that doesn\'t compromise the sensory characteristics and physicochemical juice. Defined dosages, the objective was to evaluate the microbiological, physicochemical and sensory orange juice from different varieties subjected to pasteurization and irradiation and develop a descriptive terminology and sensory profile of orange juice. The sensorial attributes analysed in this study were appearance, smell, flavor and texture. The samples were evaluated by a trained painel of nine tasters and evaluated for acceptance, with seven-point hedonic scale for fifty tasters. In view of these results, gamma radiation and pasteurisation contributed to the reduction of microbiological counts. However, sensory, treatments with 4.5 and 6.0 kGy were considered the limit of acceptability for flavor and overall impression. The doses studied showed little impact on the physical and chemical characteristics, independent of the citrus varieties. Treatment with 3.0 kGy resulted in juice with aroma and sharp taste of medicine and baked, which will probably have a negative influence on the acceptability of the product

<p>In dairy processing, dairy ingredients need to be thermally treated to ensure product quality and safety for an extended shelf life. During thermal processes, milk protein denatures and interacts with other dairy ingredients to form a layer of deposit on heated surfaces, known as fouling which can deteriorate process efficiency and product safety. Milk is a complex mixture of proteins, fats, carbohydrates, minerals and vitamins. The heat-sensitive B-lactoglobulin (B-lg) is known to be a key component in fouling formation (constituting 50% of type A fouling deposits) during milk pasteurization, as B-lg unfolds when heated and exposes the reactive sulfhydryl groups that can interact with other proteins and ingredients to form deposits. Although casein (80% of milk proteins) is known to interact with denatured B-lg, no fouling studies have been performed with particular focus on the effect of casein on whey protein fouling.</p><p>Carbohydrates are an ingredient widely added in various dairy products as sweetener, stabilizer, texturizer, and fat replacer. Simple sugars have a protective effect on whey protein denaturation, but their effect on dairy fouling is not known. Polysaccharides can interact with milk proteins through electrostatic and hydrophobic interactions, as well as hydrogen bonding. The addition of polysaccharide (carrageenan) has been reported to cause opposite effects on protein deposition, however, no conclusive mechanism has been proposed to elucidate how protein-polysaccharide interaction at pasteurization temperatures affects the fouling behavior of dairy products.</p><p>In this dissertation, different model dairy solutions and real dairy products were used to study the effect of composition, including protein distribution and additions of simple sugars and polysaccharides, on dairy fouling. Fouling deposits were formed and analyzed using a bench-top spinning disc apparatus operating under well-controlled temperatures and shear stresses characterized by computational fluid dynamics simulations. By studying the fouling behavior of camel milk and comparing with bovine milk, milk without B-lg was found to still foul and form deposits containing casein, α-lactalbumin, serum albumin with a reduced thermal resistance due to a more porous structure. Results also showed that the addition of 10 wt% sugar reduced whey protein fouling by more than 30% and affected the structure and adhesion strength of deposits. Furthermore, the presence of carrageenan in dairy solutions can promote the denaturation of B-lg when heated and form a more compact deposit, resulting in more severe fouling. Overall, this dissertation provides a fundamental understanding of the fouling characteristics of complex dairy products. The knowledge gained is expected to help the dairy industry select suitable ingredients to mitigate or prevent the fouling problem.</p>

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The purpose of this study was to determine the impact of key process parameters on the flow properties of a novel High Protein Dairy Food (HPDF). HPDF was manufactured by an approach similar to that of manufacture of Halloumi cheese (a semi hard cheese originally from Cyprus). The effect of pasteurization condition, pH of acidification and homogenization were investigated on flowability, composition and texture of the HPDF. The study consisted of three different stages. After each stage of experimentation, the HPDF was analyzed for compositional, textural (by texture profile analysis) and flow properties during heating by microwave, oven and hot water was measured by Schreiber melt test. The first stage of experimentation screened 18 batches of HPDF under three levels of pasteurization conditions (191°F/16 sec, 175°F/16 sec and 161°F/16 sec), three levels of pH of acidification (5.8,6.2 and 6.6) and two levels of homogenization conditions (two stage homogenization (2000 psi/500 psi) and no homogenization). Based on the results of the first stage, a statistically powerful second stage of experiment was designed in which two levels of pasteurization condition (191°F/16 sec and 161°F/16 sec) and three levels of pH of acidification (5.8, 6.2 and 6.6) were employed in duplicate to manufacture HPDF. The third stage of experimental design was to investigate the effect of two-stage homogenization treatment (2000 psi/500 psi) with two levels (homogenization and no homogenization). The results of all three stages of experimentation proved that HPDF made from milk pasteurized under higher pasteurization condition (191°F/16 sec) had significantly higher flow resistance under all three heating conditions. There was significant interaction between pH of coagulation of milk and pasteurization condition on flow properties of HPDF with pH of coagulation 5.8 restriction flow of HPDF under all three heating conditions. The role of homogenization in restricting flow of HPDF was not significant, although the mean flow of HPDF, made from homogenized milk, decreased. The mean protein content and mean moisture content of HPDF was significantly affected by all three processing conditions, although the mean fat content of HPDF was not influenced by any of these conditions. The mean fat, protein and moisture content of HPDF were in the range of 10.5-11, 26-34 and 47-54 percent respectively. The primary textural properties affected significantly by the processing condition were hardness, chewiness and gumminess. Particularly, hardness was influenced by higher pasteurization condition and lower pH of acidification. Further, to judge the consumer acceptability of HPDF, various recipes made out of HPDF with different heating applications (baking, stir-frying and soup) were served to 12 panelists of DPTC. Their opinions were collected and analyzed statistically. The analysis of limited focus group survey showed that consumer liking for HPDF recipe was significantly influenced by prior familiarity with the recipe, although there was some preference for HPDF over tofu due to its ‘dairy’ flavor. When the texture of HPDF manufactured from milk pasteurized at 191°F/16 sec and pH of acidification 5.8 and 6.2 were compared with various commercial protein sources, the hardness of the HPDF was very close to extra firm tofu. All the other textural properties of HPDF were significantly different from firm, silken, baked or reduced fat tofu. From this project, it is evident that a high protein food, which can be part of day-to-day human diet and potential tofu alternative, can be obtained using halloumi approach by optimizing pasteurization condition (191°F/16 sec) and pH of coagulation (5.8).

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