Syneresis is an integral part of cheese manufacture. The rate and extent of syneresis affect the properties of cheese. There are many factors that affect syneresis, but measured results vary because of inaccuracies in measuring techniques. To better control syneresis, an accurate mathematical description must be developed. Current mathematical models describing syneresis are limited because of inherent error in measuring techniques used to develop them. Developing an accurate model requires an accurate way to measure syneresis. The curd becomes a particle in a whey suspension when the coagulum is cut. The most effective technique to measure particle size, without interference, is with light. Approximations to rigorous Maxwellian theory render useable results for a variety of particle sizes. Assumptions of Fraunhofer diffraction theory relate absorption to the cross sectional area of a particle that is much larger than the wavelength of light being used. By applying diffraction theory to the curd-whey system, this researcher designed a new apparatus to permit measurement of large particle systems. The apparatus was tested, and calibrated, with polyacrylic beads. Then the syneresis of curd was measured with this appaatus. The apparatus was designed to measure particles in suspension. Until some syneresis takes place, curd does not satisfy this condition. Theoretical assumptions require a monolayer of scattering centers. The sample container must be thin enough to preclude stacking of the particles. This presents a unique problem with curd. If the coagulum is cut in the sample cell, it adheres to the front and back surfaces and does not synerese. The curd must be coagulated and cut externally and transferred to the sample cell with a large amount of whey. This measurement technique has other limitations that may be overcome with commercially available accessories.

No description available.

Curd syneresis, a critical step in cheesemaking, directly influences the quality of cheese. The syneresis process is empirically controlled in cheese manufacturing plants. A sensor technology for this step would improve process control and enhance cheese quality. A light backscatter sensor with a Large Field of View (LFV) was tested using a central composite design over a broad range of cheese process conditions including milk pH, calcium chloride addition level, milk fat to protein ratio, temperature, and a cutting time factor (β). The research objectives were to determine if the LFV sensor could monitor coagulation and syneresis steps and provide information for predicting pressed curd moisture. Another objective was to optimize cheese yield and quality. The LFV sensor was found to monitor coagulation and syneresis and provide light backscatter information for predicting curd moisture content. A model for relating final curd moisture content with light backscatter response was developed and tested. Models for predicting whey fat losses, pressed curd moisture, and cheese yield were successfully developed (R2>0.75) using the test factors as independent variables. This was the first attempt to develop a technology for controlling pressed curd moisture using a sensor to monitor the syneresis step.

This diploma thesis was focused on the system of agarose hydrogels with micellar domains. Polysaccharide agarose was used for the preparation of hydrogel matrices. Septonex was chosen as a surfactant. The release of solubilizate from the agarose hydrogel matrix was studied with a hydrophobic dye Sudan III in order to obtain a model system of hydrophobic solubilized drugs. Sudan III was solubilized via surfactant´s micels. Subsequently, this micellar aqueous solution with the dissolved dye was used to prepare the agarose hydrogel. The system was prepared in the environment of deionized water and physiologic solution. The gradual release of the dye into deionized water and physiologic solution was studied for 22 days using the UV-VIS spectrophotometry method. It was found that after 14 days the concentration of the releasing dyes into the deionized water was decreased. The cause is that after 14 and 22 days there was a slight degradation of gels, which was detected using the rheology method. Using the rheology method it was also found that Septonex does not affect the gel formation process.

The Western Dairy Center at Utah State University funded this project to investigate cheese research using concentrated milks. Concentrated milk was provided by the South Dakota State University and starter culture for this study was prepared and donated by Vivolac Cultures Corporation, Greenfield, Indiana. The project initiated as a continuation of a previous study on effects of protein concentration, coagulum cut size and set temperature on curd moisture loss kinetics while stirring during cheesemaking. It was aimed at determining the extent to which pH drop prior to draining and final cheese moisture when using microfiltered concentrated milk. We performed twelve cheesemaking trials using recombined milk from micellar casein concentrate, cream and skim milk according to a modified cheddar cheese-make procedure. Four different levels of starter cultures were used to achieve different acidification rates for pH change during cheesemaking. The amount of starter culture added had significant effect on moisture of cheese at whey drainage, moisture and pH of cheese. Thus, it can be said that the pH drop that occurs during the cheesemaking increases rate and extent of whey expulsion.

Master of Science / Food Science Institute, Animal Science and Industry / Karen A. Schmidt / Yogurt is a good source of whey proteins, which have been reported to provide positive health benefits. During yogurt manufacture, the yogurt mix receives a heat treatment which pasteurizes the product, denatures the whey proteins affecting their availability, and enhances quality attributes. Thus the objective of this research was to improve the undenatured whey protein content in yogurt. The study was divided in two parts. The first part focused on the effect of pasteurization treatments of yogurt mixes (65 °C for 30 min vs. 90 °C for 10 min) on the yogurt firmness, G’, L*, syneresis and water holding capacity (WHC), and how these properties change as a function of storage. Nonfat dry milk (NFDM) was reconstituted (~11% w/v) pasteurized, cooled, inoculated with yogurt culture, incubated to pH 4.5, stored at 5 °C ±1 and evaluated for various physical and chemical properties on days 1, 15 and 29. The experiment was replicated 3 times and data were analyzed by SAS®. Yogurt samples had a 5-fold difference in whey protein denaturation (WPD) and the greater the WPD the greater the firmness, G’, L* and WHC but lesser the syneresis. During yogurt storage, L*, G’, syneresis and WHC increased. The second part of this research focused on whey protein concentrate (WPC) addition (3%) in yogurt mix combined with two pasteurization treatments (70 °C for 30 min vs. 90 °C for 10 min) to determine their effects on the yogurt quality. Yogurt mixes were formulated using 12.5% NFDM or 9.5% NFDM and 3% WPC and a procedure similar to the previous study was followed. The WPC addition resulted in a yogurt with decreased firmness, G’, WHC but increased syneresis. Yogurt made from mixes pasteurized at 90 °C for 10 min had ~60% WPD and comparable quality attributes regardless of WPC addition. Thus, additional WPC and less WPD in this study resulted in a yogurt with slightly lesser quality attributes but more undenatured whey proteins in the final yogurt.

Baigiamasis darbas atliktas Lietuvos Žemės ūkio universitete 2006 - 2008 metais. Magistro baigiamąjį darbą sudaro įvadas, 3 skyriai, išvados, literatūros sąrašas ir priedai. Darbo apimtis 48 puslapių, juose 25 paveikslai, 8 lentelės, naudotasi 46 literatūros šaltiniais. Tiriamojo darbo tikslas - padidinti plataus vartojimo, kasdienio produkto – rauginto pieno biologinę vertę, panaudojant sausąsias išrūgas, siekiant pagerinti jį vertingomis mineralinėmis medžiagomis, smulkiadispersiniais (unikaliais) baltymais ir angliavandeniu – laktoze. Ištirti sausųjų išrūgų priedo įtaką rauginimo procesui, fizikinėms – cheminėms surauginto pieno savybėms bei jų kitimą laikymo metu. Darbe ištirta sausųjų išrūgų įtaka rauginto pieno savybėms. Įdėjus sausųjų išrūgų padidėja rauginto pieno biologinė vertė, papildant produktą vertingomis mineralinėmis medžiagomis, smulkiadispersiniais (unikaliais) baltymais ir angliavandeniu – laktoze. Sausųjų išrūgų priedas iki 2 % padidina nepakeičiamų amino rūgščių ir mineralinių medžiagų kiekį. Bendras nepakeičiamų amino rūgščių kiekis padidėjo 1068 mg/l, o bendras mineralinių medžiagų kiekis 1727 mg/l (tame kiekyje kalcio padidėjo 220 mg/l, kalio 280 mg/l, natrio 220 mg/l). Nustatyta, kad sausųjų išrūgų priedas iki 2 % nepakeičia tradicinių rauginto pieno juslinių savybių. Gauta, kad mėginiuose suraugintuose su sausųjų išrūgų priedu padidėja LLRR kiekis, šiek tiek sumažėja rūgštinio gelio klampumas, tačiau padidėja išrūgų imobilizavimo galimybės. Su 1 %... [toliau žr. visą tekstą] / Work size - 48 pages, including 25 pictures, 8 tables. List of literature - 46 sources. The beginning of the work -2006 09 01, the end of the work - 2008 05 13. The article analyzes the influence of dry whey on the properties of sour milk, when the dry whey is added. The biological value of sour milk – daily product of wide usage – increases when it is enriched with valuable mineral substances, small-dispersive (unique) albumens and carbohydrate – lactose. The addition of dry whey up to 2 % increases the amount of irreplaceable amine acids and mineral substances. The total amount of irreplaceable amine acids increased by 1068 mg/l, while total amount of mineral substances increased by 1727 mg/l (including increase of calcium by 220 mg/l, potassium – 280 mg/l, sodium 220 mg/l). It was determined that the addition of dry whey up to 2 % does not change the traditional sensitive properties of sour milk. It resulted that when the dry whey was added, LLRR amount increased in the sour samples, the viscosity of the structure of sour gel decreased a little, but the immobilization possibilities of the whey increased. The addition of dry whey of 1 % results in emission of whey in the process of syneresis (in 2 hours) decreased by 6 %, and 2 % - with 17 %. The determined change of physical-chemical indexes during the storage of sour samples (the amount of LLRR in the beginning of storage up to 2 days increased, and later started to decrease). The change of structure of acid gel happens... [to full text]

Made available in DSpace on 2015-04-17T14:49:16Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1272716 bytes, checksum: d982a13cfede81d5211e1cb2bb68ab85 (MD5) Previous issue date: 2011-09-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The dairy sector is seeking to produce foods with functionality as main attribute. In this context, a market to be explored is that of dairy goats, since goat milk is a food alternative of excellent dietary and nutritional characteristics. However, due to its physical and chemical characteristics, the milk produces a soft clot after fermentation, giving a product with poor texture. The objective of this study was to develop a goat milk fermented by the action of probiotic strains Lactobacillus acidophilus LA-5, Bifidobacterium BB-12 and Streptococcus thermophilus added of the prebiotic ingredient inulin and thickeners starch and gelatin and to evaluate its physicochemical composition susceptibility to syneresis, bacterial counts and sensory analysis on the first day of preparation and after 15 days of refrigerated storage. The tests were elaborated according to a factorial experimental design with three levels and three central points totaling eleven trials. The minimum and maximum levels were selected based on legal limits, literature data and preliminary tests considering the sensory quality evaluated by tasters. Starch, gelatin and inulin represented the variable ingredients and the fixed ingredients were: milk powder, sugar, milk and yeast. The process steps were milk weighing, mix preparation, heat treatment, cooling, direct inoculation, incubation, cooling, clot breaking, filling and storage. The developed formulations met the legal requirements for fermented milk regarding protein, fat and acidity average values. The starch and gelatin levels, combinations and interaction with inulin were sufficient to promote a significant decrease in the serum separation rate. Most formulations reached the minimum number of microorganisms required by legislation for fermented milk. The sensory properties appearance, color and consistency achieved high scores and aroma and flavor scored around five. In general, no significant changes were observed in the counts of probiotic bacteria and sensory quality of the newly developed formulations in relation to formulations after 15 days of refrigerated storage. The addition of probiotic bacteria and prebiotic ingredient inulin improved the potential of goat milk to provide beneficial effects to human health. / O setor lácteo busca produzir alimentos tendo como atributo principal a funcionalidade. Nesse contexto um mercado a ser explorado é o de lácteos caprinos, uma vez que, o leite de cabra representa uma opção alimentar de excelentes qualidades nutricionais e dietéticas. Contudo, em razão de suas particularidades físicas e químicas, após a fermentação do leite, gera um coágulo macio, conferindo um produto pobre em textura. O objetivo deste trabalho foi desenvolver um leite de cabra fermentado mediante ação das cepas probióticas Lactobacillus acidophilus LA-5, Bifidobacterium BB-12 e da bactéria Streptococcus thermophilus, adicionado do ingrediente prebiótico inulina e dos espessantes amido e gelatina bem como avaliar sua composição físico-química, susceptibilidade à sinérese, contagem das bactérias e análise sensorial no primeiro dia da elaboração e após 15 dias de armazenado refrigerado. Os ensaios foram elaborados segundo um planejamento experimental do tipo fatorial com três níveis e três pontos centrais totalizando onze ensaios. Os níveis mínimos e máximos foram escolhidos com base nos limites legais, dados da literatura e testes preliminares considerando a qualidade sensorial emitida por degustadores. O amido, gelatina e inulina representaram os ingredientes das variáveis e os ingredientes fixos foram: leite em pó, açúcar e fermento lácteo. As etapas do processo foram pesagem do leite, preparo da mistura, tratamento térmico, resfriamento, inoculação direta, incubação, resfriamento, quebra do coágulo, envase e armazenamento. As formulações desenvolvidas atenderam as especificações legais para um leite fermentado quanto aos valores médios de proteínas, gordura e acidez. Os teores e combinações de amido e gelatina e suas interações com inulina foram suficientes para promover uma diminuição significativa no índice de separação do soro. A maioria das formulações atingiu o número mínimo necessário de micro-organismos estabelecido na legislação para um leite fermentado. As propriedades sensoriais aparência, cor e consistência alcançaram notas altas e o aroma e sabor obtiveram notas em torno de cinco. De um modo geral não houve alteração significativa na enumeração das bactérias probióticas e na qualidade sensorial das formulações recém-elaboradas em relação às formulações após 15 dias de armazenamento refrigerado. As adições das bactérias probióticas e do ingrediente prebiótico inulina poderão ampliar, ainda mais, a potencialidade do leite caprino em prover efeitos benéficos à saúde das pessoas.

Orientador: Mirna Lucia Gigante / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-12T19:47:23Z (GMT). No. of bitstreams: 1 Hatanaka_CamilaLie_M.pdf: 549349 bytes, checksum: c5f48036602609500f035f399d2cb21c (MD5) Previous issue date: 2009 / Resumo: Atualmente a adição de hidrocolóides é um recurso utilizado em produtos lácteos para modificar a textura ou evitar defeitos como a sinérese. Hidrocolóides são utilizados como agentes espessantes, gelificantes e estabilizantes, e podem apresentar características sinérgicas quando utilizados em conjunto. O objetivo deste trabalho foi avaliar o efeito da adição de goma tara e carragena sobre a sinérese do iogurte firme desnatado. Os iogurtes foram fabricados com leite desnatado reconstituído adicionado de goma tara e carragena, em concentrações variando de 0 a 0,0585%, em combinações previstas pela metodologia de superfície de resposta. Após aproximadamente 48 horas de armazenamento refrigerado, determinou-se a composição dos iogurtes e a sinérese, que foi avaliada de três formas distintas: sinérese espontânea, por drenagem e por centrifugação. A goma tara afetou significativamente a sinérese do produto, que aumentou em concentrações superiores a 0,0293%, independentemente da sua forma de avaliação. A sinérese não foi significativamente afetada pela adição de carragena e nem pela interação entre os polissacarídeos. As concentrações escolhidas para fabricação e avaliação dos iogurtes durante o armazenamento refrigerado (29 dias) foram iogurte controle (sem adição de polissacarídeos), iogurte com 0,02% de goma tara e iogurte com 0,02% de tara + 0,02% de carragena. Após aproximadamente 24 horas os iogurtes foram avaliados quanto à composição centesimal. Durante o armazenamento refrigerado, após 1, 8, 15, 22 e 29 dias de fabricação os produtos foram avaliados quanto à sinérese espontânea, firmeza, e pH para acompanhamento da pós-acidificação. A sinérese espontânea foi significativamente afetada pelos tratamentos, sendo que a menor liberação de soro foi observada para o iogurte fabricado com goma tara e carragena, enquanto que o iogurte que continha apenas goma tara apresentou maior sinérese. A firmeza foi significativamente afetada pelos tratamentos. O iogurte fabricado com goma tara e carragena apresentou menor firmeza quando comparado ao iogurte controle, sendo que ambos não diferiram significativamente do iogurte fabricado com goma tara. Durante o tempo de armazenamento refrigerado a firmeza dos iogurtes aumentou significativamente. Os tratamentos afetaram significativamente a pós-acidificação dos iogurtes, sendo que o iogurte controle apresentou menor pH quando comparado ao iogurte fabricado com adição de goma tara e carragena. O pH de todos os produtos diminuiu significativamente nos primeiros 8 dias de armazenamento refrigerado, mantendo-se estável após esse período / Abstract: Nowadays, the hydrocolloids addition is an applied mean to modify the texture or to avoid defects, such as syneresis, in dairy products. Hydrocolloids can be utilized as thickening, gelling and stabilizing agents, and can show synergistic features when applied along each other. The objective of this research was to evaluate the effect of addition of tara gum and carrageenan on the syneresis of non-fat set yogurt. Non-fat reconstituted milk added with carrageenan and tara gum in concentrations from 0 to 0.0585%, at combinations given by response surface methodology, was used. Composition and syneresis (spontaneous, by drainage, and by centrifugation) evaluations were done after 48 hours of cold storage. Tara gum significantly affected the syneresis, increasing it in concentrations higher than 0.0293%, independent of the type of syneresis evaluation. The effects of carrageenan and polysaccharides¿ interaction on the syneresis were not significative. The concentrations evaluated during 29 days were control yogurt (no polysaccharide addition), yogurt with 0.02% of tara gum and yogurt with 0.02% of tara gum and 0.02% of carrageenan. Composition was evaluated approximately after 24 hours. The pH (for post-acidification evaluation), spontaneous syneresis and firmness were evaluated during the cold storage at 1, 8, 15, 22 and 29 days after manufacture of yogurts. Natural syneresis was affected by the treatments and yogurt with tara gum and carrageenan showed the lowest whey-off, while the yogurt containing only tara gum showed the highest syneresis. Firmness was significantly affected by treatments. The lowest firmness was observed in yogurt containing carrageenan and tara gum, when compared to control yogurt, but both yogurts didn't differed from yogurt containing only tara gum. Yogurt firmness increased during cold storage. Regarding the post-acidification, the treatments significantly affected the pH and the control yogurt showed the lowest pH, if compared to yogurt manufactured with tara gum and carrageenan. The pH of all yogurts significantly decreased at the first eight days of cold storage, stabilizing during cold storage / Mestrado / Mestre em Tecnologia de Alimentos

The dairy food industry is continuously striving towards products with higher quality and longer shelf-life available to the customer at low prices. Arla Foods in Linköping, Sweden, is currently investigating the possibilities of changing the material in yogurt packaging containers by replacing the currently used carton with a different and cheaper alternative. A successful switch will give the company an economical advantage without affecting the sensory attributes (smell, taste, sight, and consistency), aroma profile or other important trademarks of the yogurt. This study is designed to examine and compare yogurt that has been stored in different packaging cartons, one coated with a single-layered low-density polyethylene (LDPE) and one coated with a currently used multi-layered ethylene-vinyl alcohol (EVOH). The study was based on the analysis and measurement of sensory attributes performed by experts, physical properties in laboratory and chemical composition in GC-FID/MS together with a discriminative test where a group of people would identify any difference between the yogurts. Together, these analyses would provide an explanation about any differences between the packaging materials by connecting physical, chemical and/or sensory characteristics. The collected results would give a better and more comprehensive picture than each analysis would do separately. The results from the study show that there is a difference between yogurts stored in LDPE-based containers and yogurts stored in EVOH-based containers and that the product was chemically affected, mainly by the level of oxygen in contact with the food. The overall assessment is that the largest difference was discovered in the taste.