Made available in DSpace on 2014-06-11T19:26:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-27Bitstream added on 2014-06-13T19:54:01Z : No. of bitstreams: 1 campos_rv_me_jabo.pdf: 253429 bytes, checksum: 8d9f4fe4ec3cc0553b735dfab36c9a5a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A eficiência em produção de uma propriedade depende de fatores técnicos, biológicos, financeiros e gerenciais. Avanços na genética, nos métodos estatísticos e na melhoria da capacidade de processamento dos computadores podem contribuir para o progresso genético do rebanho bubalino. Sendo assim, o objetivo deste estudo foi verificar a associação genética entre a produção de “mozzarella” (PM) com a produção e os constituintes do leite bubalino considerando como objetivo de seleção a PM. Para isso, estimaram-se os parâmetros genéticos das produções de leite (PL) e “mozzarella”, bem como das porcentagens de gordura (PG) e proteína (PP), utilizandose 4389 lactações ocorridas entre os anos 1985 e 2005. Estimou-se ainda o ganho e a tendência genética das características ao longo dos anos bem como a eficiência da seleção. Estimou-se os componentes de variância por meio de análises bi-característica usando modelos animal, pela metodologia REML, ao qual foram obtidas as estimativas de herdabilidade que variaram de 0,17 a 0,37 entre todas as características analisadas, o que indica que existe variabilidade passível de seleção. As repetibilidades também foram altas, de 0,42 a 0,63, indicando que poucos desempenhos podem ser considerados para se praticar o descarte de animais através da seleção. A correlação genética entre as PL acumuladas aos 270 (P270) e 305 (P305) dias com a PP foram negativas e mediana (-0,04 e -0,29, respectivamente) e com a PG foram negativas e alta (-0,56 e -0,68, respectivamente) acarretando na diminuição dos constituintes à medida que se seleciona para as PL. Com base nas altas correlações genéticas entre as PL com a PM (acima de 0,86) e nas respostas correlacionadas visando à PM, é mais indicado praticar seleção direta para a PL devido ao seu maior peso na fórmula de estimação da mesma, ainda que os teores dos... / The efficiency in production of a farm depends factors technical, biological, financial and managerial. Progresses in the genetics, in the statistical methods and in the improvement of the capacity of processing of the computers they can contribute with the genetic progress of the herd buffalo. The objective of this study was to verify the genetic association among the mozzarella yield (MY) with the yield and components composition of the milk buffalo considering as selection objective the MY. They were considered the genetic parameters of the yield of milk (YM) and mozzarella, as well as of the fat percentages (FP) and protein (PP), being used 4389 lactations happened among the years 1985 and 2005. Estimation also the genetic gain, the efficiency and the tendency of the selection along the years. It was used for the analysis of the environmental factors and definition of the models of the characteristics the procedure GLM of the SAS. For the study of the genetic factors, they were considered the variance components across analyses bi-characteristic using models animal, across of the methodology REML of MTDFREML, to which was obtained the heritability estimates that varied from 0,17 to 0,37 among the characteristics, what indicates that variability susceptible to selection. The repeatability were also high, from 0,42 to 0,63, indicating that few performance can be considered to be practiced the selection. With base in the correlated answers to the MY, it is more suitable to practice direct selection for the MY due to your largest weight in the formula of estimate of the mozzarella, even if the representative’s component constituents are maximum. Besides, it is treated of a characteristic of easy measure and low cost, allowing larger number of animals to be controlled...(Complete abstract, click electronic access below)

Made available in DSpace on 2014-06-11T19:26:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-11-29Bitstream added on 2014-06-13T18:55:08Z : No. of bitstreams: 1 buzi_ka_me_bofmvz.pdf: 312188 bytes, checksum: dc8abb2b8c6363a59f058f66fdc27742 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente trabalho visou avaliar a qualidade microbiológica de queijos mussarela elaborados a partir de leite de búfala, adquiridos do comércio varejista, assim como, verificar a sua autenticidade, averiguando a possível presença de leite de vaca no produto. As análises microbiológicas compreenderam em contagem de coliformes totais e E. coli, contagem de Staphylococcus coagulase-positiva e pesquisa de Salmonella spp.; enquanto que, para a determinação da pureza das mussarelas, a técnica utilizada foi a eletroforese em gel de poliacrilamida. Com base nos resultados obtidos na avaliação microbiológica, pode-se afirmar que 98% das amostras estão dentro dos padrões microbiológicos legais vigentes, embora algumas delas tenham apresentado valores para coliformes totais entre 103-106 UFC/g, indicando provavelmente condições inadequadas de higiene durante a fabricação dos queijos. Entretanto, 2% das amostras encontram-se em desacordo com a legislação, uma vez que apresentaram populações de coliformes fecais acima do permitido, como resultado de uma alta contaminação por E. coli. Mediante a caracterização eletroforética, detectou-se a presença de leite de vaca em 22% das amostras, adicionado, provavelmente, de forma intencional. / This study evaluated the microbiological of mozzarella cheese made from buffalo milk bought in retail outlets and validated their authenticity by checking the product for the possible presence of cow milk. Microbiological analysis included counts of E. coli, total coliform, positive coagulase Staphylococcus, and Salmonella spp. For the determination of mozzarella purity, we used polyacrylamide gel electrophoresis. Based on the results of the microbiological evaluation, we can state that 98% of samples are within the legal microbiological standards, although some have shown values of total coliforms between 103-106 UFC/g, which indicates poor conditions and hygiene during cheese manufacture. However 2% of samples showed fecal coliform populations outside the legal limits as a result of a high E. coli contamination. Electrophoresis detected cow milk in 22% of the samples which was probably added intentionally.

Muçarela de búfala é um queijo fresco, de massa filada, que apresenta características como coloração branca, sabor adocicado e alto valor nutricional e que tem grande aceitação pelos consumidores, dispostos a pagar preços diferenciados pela peculiaridade do produto. No entanto, o queijo está sujeito à violação de autenticidade, tanto pela sazonalidade da produção do leite da búfala quanto pelo alto preço do leite e do queijo, quando comparado aos similares oriundos da vaca, bem como à contaminação microbiana. Assim, este trabalho teve por objetivos avaliar a ocorrência de fraude na muçarela de búfala por adição de leite de vaca, e a influência da sazonalidade da produção do leite de búfala na frequência desta adulteração, bem como avaliar a presença de alguns patógenos no queijo comercializado no município de São Paulo. Amostras de muçarela de bolinha cujo rótulo identificava o uso exclusivo de leite de búfala foram submetidas à pesquisa de DNA bubalino e bovino, usando primers para detecção do gene citocromo b (cytb), e à análise microbiológica. A fraude foi detectada em 73% das amostras (77/106), não havendo influencia da sazonalidade; em duas amostras (2/106) apenas o DNA bovino foi detectado. Do ponto de vista microbiológico, todas as amostras apresentaram ausência de Listeria monocytogenes e de Salmonella spp. em 25 gramas, mas 7% (10/138) foram consideradas impróprias para o consumo humano por apresentar Coliformes termotolerantes e/ou Staphylococcus coagulase positiva acima dos limites estabelecidos pela legislação vigente. Conclui- se que a fraude por adição de leite de vaca é muito frequente e não é motivada apenas pela redução sazonal da oferta do leite bubalino. Além disso os problemas microbiológicos detectados estão associados às inadequadas condições de higiene da matéria prima e/ou do processo de fabricação e/ou abuso de temperatura de armazenamento do queijo. / Buffalo mozzarella is a fresh cheese, filada mass, with characteristics such as white color, sweet taste and high nutritional value and has great acceptance by consumers willing to pay different prices for the uniqueness of the product. However, the cheese is subject to violation of authenticity, both the seasonality of production of milk the buffalo as by the high price of milk and cheese when compared to similar coming from the cow as well as to microbial contamination. This work aimed to evaluate the occurrence of fraud in buffalo mozzarella by adding cow\'s milk, and the influence of the seasonality of production of buffalo milk in the frequency of this tampering and evaluate the presence of some pathogens in cheese marketed in São Paulo. Mozzarella samples of marble whose label identified the exclusive use of buffalo milk were subjected to DNA research buffalo and cattle, using primer for detection of cytochrome b gene (cytb), and microbiological analysis. The fraud was detected in 73% of samples (77/106), with no influence of seasonality; in two samples (2/106) only the bovine DNA was detected. From a microbiological point of view, all samples showed no Listeria monocytogenes and Salmonella spp. 25 grams but 7% (10/138) were considered unfit for human consumption by presenting thermotolerant coliforms and / or coagulase positive Staphylococcus above the limits established by law. It is concluded that fraud by adding cow\'s milk is very common and is not motivated only by the seasonal reduction in supply of buffalo milk; microbiological problems encountered are related to inadequate hygiene conditions of raw materials and / or fabrication process and / or storage temperature abuse cheese.

Variables affecting the physical properties of Mozzarella cheese were investigated. The effects of various milk-clotting enzymes were examined. The type of milk coagulating enzyme used played a significant role in determining physical properties of direct acid Mozzarella cheese. Cook color was not affected by enzyme type, but melt and stretch were significantly affected. Proteolytic nature of starter cultures was reviewed and recommendation s were give n. Cheese made with proteinase-deficient strains had more stretch after holding for 14 and 28 d than cheese made with non-deficient strains. Cheese made with pairs or single strains of L. helveticus had the same melt, more stretch, and less cook color than cheeses made with paired strains of Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus salivarius ssp. thermophilus. Frozen storage, thawing, and shredding of Mozzarella cheese were described and suggestions given for optimizing shelf life. Shredding, freeze temperature, thaw temperature , and time of storage had no effect on cook color. Frozen, shredded cheese stretched more and melted less than non-shredded frozen cheese. Reduced fat, high moisture Mozzarella cheese was made and found acceptable when compared to low moisture part-skim Mozzarella cheese. Reduced fat cheeses decreased in stretch and increased in melt throughout storage. Differences in stretch, melt, and cook color were not significant from one casein-to-fat ratio to another. Reduced fat, high moisture Mozzarella cheese was made with partial or total replacement of L. helveticus with L. casei ssp. casei and was found to compare well with low moisture part-skim Mozzarella cheese. Cheese made with L. casei ssp. casei cultures, paired with either S. salivarius ssp. thermophilus and L. helveticus or just S. salivarius ssp. thermophilus, had the least stretch and the greatest melt.

The effect of reducing the fat content of low-moisture part-skim Mozzarella cheese from 19% to less than 5% on melted cheese properties, i.e., apparent viscosity, cheese melt, and cook color, was investigated. Functional properties of melt and stretch and cook color were evaluated at d 1, 7, 14, and 28. A rapid microwave oven method underestimated the moisture content of the low fat cheeses by approximately 10%. Low fat cheese did not melt as well as did the low-moisture part-skim Mozzarella cheese although the moisture content of the low fat cheese (moisture content ranged from 62.5% to 63.6%) was greater than the moisture content of the part-skim control (52.1 %). Storage for 28 d only marginally increased the meltability of low fat cheese. Lower fat content increased cook color. The amount of intact a αs-CN decreased by at least 48% in all cheeses as a result of proteolysis during 28 d of storage. The relative proportion of bound, entrapped, and expressible water was determined for a reduced-fat (8% fat) and control (19% fat) Mozzarella cheese on d 1, 7, 14, and 21 of refrigerated storage. Changes in the state of water were related to changes in cheese microstructure of a commercial Mozzarella cheese and to changes in cheese meltability of the control cheese. The amount of expressible water was proportional to fat content. Throughout storage, fat/serum channels became smaller and the protein matrix expanded into the areas between fat globules. The meltability of both cheeses increased during storage. Both cheeses contained 0.71g bound water/ g protein. Expressible water decreased in both cheeses until by d 21 no water was expressible. Entrapped moisture increased from approximately 10% to 60% for the control cheese and from approximately 33% to 50% for the reduced-fat cheese. An objective test was developed for measuring stretch, a characteristic of melted cheese. Three nonfat and four low-moisture part-skim cheeses were evaluated using the new test and the results compared with conventional test methods. Two new melted cheese parameters were defined: melt strength, the maximum load (g) obtained during the test, and stretch quality, the average load (g) as the cheese fibers stretched and elongated. Melt strength correlated with apparent viscosity. Stretch quality was determined for selected nonfat and low-moisture part-skim cheeses. A three-pronged probe was used to pull cheese vertically from a melted cheese pool. Use of this elongation stretch test, along with more traditional melted cheese tests, provides more complete information about the functional properties of Mozzarella cheese.

The Mozzarella cheese market is growing rapidly. Major concerns with cheese meltability and color have arisen in the fast food industry. Pre starter culture was used in this study to improve the physical properties of Mozzarella cheese. Three tests (stretch test, melt test, and browning test) were modified to evaluate the quality of cheese. A stretch test using the Brookfield helipath viscometer to stretch the cheese sample at 60°C was successful in distinguishing cheeses from different make procedures and from different proteolytic strains. A melt test using a glass tube to hold the cheese flow at 110°C for 60 min was used to determine meltability of cheese. A chroma meter was used to measure color change after the cheese sample was subjected to boiling water for 60 min. The b* value was used to indicate the color change. Cheese made with Pre strains of Lactobacillus bulgaricus stretched less but showed longer melting flow than that from Prt+ strains. Cheese made with Pre strains was lighter in color than cheese from Prt+ strains. An inverse relationship existed between stretchability and meltability. When mixed cultures of L. bulgaricus and Streptococcus thermophil us were used, the symbiotic interaction in acid production of Prt+ strains was more effective than mixed cultures of Prt- strains. Stretchability of...

Mozzarella cheese was made from milk fortified with iron so that the cheese contained 25 and 50 ppm iron. Iron was added to the milk in three ways: (1) complexed to casein (ferric-casein), (2) complexed to whey protein (ferric-whey protein), and (3) ferric chloride (FeCl3·6H20) added directly to milk. Cheese quality was determined by chemical, physical, and sensory characteristics and compared with a control cheese. Chemical oxidation, during 28 days storage, was determined by absorbance of malondialdehyde at 535 nm using the thiobarbituric acid assay (TBA). Physical properties were assessed by the Arnott test for melt, helical viscometer for stretch, and b* value for cook color. Sensory properties were tested by panelists trained to detect metallic and oxidized off-flavors and by large, untrained consumer panels. There were no significant differences in iron-fortified cheeses based on the method of adding iron to milk. There were no significant differences in TBA-measured oxidation caused by adding iron, method of adding iron, or by storage ( α=.05). Stretch was increased by addition of iron. Melt and cook color were not affected by iron fortification. The trained sensory panel scored metallic and oxidized off-flavors slightly higher in the iron-fortified cheeses than in the controls, although at a level that was slightly perceptible. When cooked on a pizza, the iron-fortified cheese was rated comparable to the control cheese by consumer panels. Based on the popularity of pizza and on these observations, it was concluded that iron-fortified Mozzarella cheese can be used as an appropriate food vehicle to supplement the diets of populations that are at risk for iron deficiency anemia (e.g., children and pregnant women).

A correlation between the USU stretch test and the pizza fork test would allow the stretch properties of Mozzarella cheese to be measured objectively. The Utah State University (USU) Stretch Test uses a modified texture-profile analyzer to pull strands of cheese from a melted reservoir, measuring the load exerted on the probe during stretching. Parameters measured by the USU stretch test include Melt Strength (FM), which is the maximum load exerted on the probe, Stretch Load (SL), which is the load exerted on the probe at any specified point following FM, and Stretch Extension (SE), which was defined as the extension of the probe at a selected load. To begin with, it was determined that the greatest repeatability and cheese performance was obtained by tempering 50 g of shredded cheese for 45 min at 65°C and using a three-pronged hook with a diameter of 25 mm as the probe. These conditions were then applied in a correlation study in which a low correlation was seen between the USU stretch test and the pizza fork test, with the greatest correlation being seen with FM (R2 = 0.22). A more extensive look at the effect of the tempering temperature used in the USU stretch test on the degree of correlation between the two tests was conducted by tempering cheeses at 65, 70, 75, 80, and 85 °C. In this experiment, the highest correlation between the two tests was seen at both 80 and 85°C. Values of R2 at 80°C for SL10-15 and SEF (Stretch Extension at FM) were 0.75 and 0.70, respectively. At 85°C, the highest degree of correlation was seen at SL10-15 (R2 = 0.72) and SE0.1 (R2 = 0.69). A multiple linear correlation study was also conducted. A high degree of correlation between the USU stretch test and the pizza fork test was seen at 80°C when two parameters were used (SEF and SL22, R2 = 0.85, Adj. R2 = 0.80) and when four parameters were used (FM, slope from 10 to 20 em, SE0.1, and SL22, R2 = 0.97, Adj. R2 = 0.93). A set of cheese was then analyzed by the USU stretch test and the pizza fork test at three different intervals of aging (21 , 40, and 60 days after manufacture). This data was combined with previously collected data to show that the USU stretch test can be used to characterize the functional properties of a cheese using the parameters of FM, SEF, as well as SE0.1. It was concluded that the USU stretch test can provide a better characterization of a pizza cheese than can the pizza fork test. Whereas the pizza fork test is only able to record the distance that the cheese can stretch, the USU stretch test is capable of measuring a variety of parameters, which provides not only an indication of how far the cheese will stretch, but also other important functional properties related to the cheese, such as viscosity, elasticity, and the thickness of the strands being stretched.

String cheese, a Mozzarella cheese, has the unique ability to string in fibrous strands when pulled apart. Graders judge string cheese by its stringy texture; samples with copious amounts of string are awarded high ratings. But just as the texture of natural cheeses softens with time, the stringy texture of string cheese can diminish with age too. Age related softening in cheese is due primarily to an important biochemical event known as proteolysis, which is attributed to inherent milk proteinases, residual coagulant activity, and enzymes from the lysis of starter culture microorganisms. It is hypothesized that a post manufacture heat treatment of string cheese could inactivate these proteolytic enzymes and slow or eliminate proteolysis during storage. Therefore, the main objective of this study was to determine the effects of a post manufacture thermal dip treatment on proteolytic activity in packaged, commercial string cheese. Proteolysis was examined qualitatively by Urea-PAGE electrophoresis, quantitatively by measuring percentage of water-soluble nitrogen (%WSN), and by using a scoring method to analyze stringy texture during refrigerated storage. Fresh, commercial string cheese was sourced on two separate occasions and treated six days after manufacture. Treatment consisted of dipping the packaged cheese sticks in water baths at 55°C, 75°C, and 95°C for 30 and 60 seconds. String cheese that did not undergo treatment served as the control. Treated and control cheeses were stored at 4°C until sampling for Urea-PAGE, WSN extraction, and texture analysis on days 1, 11, 22, 29, 49, 91, and 172 after treatment. The degree of β-CN breakdown was not observed to be different between all treatment levels throughout the storage period. This was not expected since Mozzarella cheese exposed to a higher temperature should have more plasmin activity than that of cheese exposed to a lower temperature. There was a trend of slightly more intact αs1-CN in the most severely treated string cheese (95°C for 60s) when compared to the control at the final time point of the study. This suggests the possibility of successful inactivation of residual coagulant, intracellular enzymes, or other proteolytic enzymes in the string cheese at this treatment. However, only storage time had a significant effect on %WSN (p The research completed in this study provides insight of the proteolytic effects from a thermal treatment process applied post string cheese manufacture. Though relationships between the treatments to the extent of secondary proteolysis and stringy texture were not significant, it was still found that there was more intact αs1-CN due to one of the treatments. These results suggest that it is possible that the use of other heat treatment parameters, longer storage period, or a combination of the two could show a significant relationship between thermal treatment and proteolysis. These results also suggest that further work to improve shelf life of string cheese or other cheese varieties through the concept of a post manufacture heat treatment may be promising.

The objective of this study was to determine the effectiveness of sorbic acid in inhibiting Escherichia coli 0157:H7, Salmonella spp., Listeria monocytogenes, and Staphylococcus aureus on shredded cheddar and mozzarella cheese over 70 days storage. Samples of cheese were inoculated and placed into bags with a sorbic acid (0, 0.1, 0.15, 0.2 and 0.3 %) and anti caking agent mixture and stored at 10 °C. Each variable was enumerated after 0,14,28,42,56, and 70 days of storage. Survival of E. coli 0157:H7 showed no significant difference from control in either cheese. There were significantly lower Salmonella counts for days 14 to 42 on mozzarella cheese. No significant differences in survival were found for cheddar cheese. There were significantly lower counts noted in L. monocytogenes, and S. aureus in mozzarella. Though no significant differences were found over time in the cheddar, most of the sorbate concentrations exhibited lower counts than control on days 14 and 28. Overall, in the presence of sorbic acid there was a more rapid decline in numbers of each test organism, especially against L. monocytogenes, and S. aureus for both high and low moisture cheeses. / Master of Science