Experiment A explored the influence of sodium on direct acid, nonfat Mozzarella cheese. Cheeses with differing salt levels were obtained by varying dry salt applications (none, 0.5%, and 1.0% NaCl w/w) and hot brine stretching (0%, 5%, and 10% NaCl wt/v). Salt application and salt content influenced cheese moisture, meltability, expressible serum, micro- and ultra-structure, and color. Moisture was highest when cheese was salted before stretching (P = 0.03) . Melt was lowest in cheeses that were unsalted (P = 0.05). Cheeses stretched in salt brine had < 1% of the amount of expressible serum found in unsalted cheese (P < 0.0001). Unsalted cheeses had a more open structure with pockets of serum distributed throughout the protein matrix giving it an opaque, white appearance. Salted cheeses had a more homogeneous protein matrix lacking light scattering surfaces, resulting in a translucent cheese. Neither salt concentration nor method of salting affected the calcium content of the cheeses (P > 0.05). Experiment B explored the influence of calcium, moisture, and pH on cheese structure and functionality. Cheeses were manufactured using combinations of citric and acetic acids. Addition of EDTA to the whey during cooking, CaCl2 fortification, and extended drain times were used to produce eight cheeses in a 23 factorial design with target pH levels of 5.8 and 5.3, 70% and 66% moisture, and 0.6% and 0.3% calcium levels. EDTA was unsuccessful in removing calcium from pH 5.8 cheese. Adding CaCh successfully increased the calcium level of pH 5.3 cheese. Cheese with 0.3% calcium had greatest melt, decreased hardness and increased adhesiveness. Cheese with 0.6% calcium had decreased melt and adhesiveness, and increased hardness. When calcium content was held at 0.6% there was no significant difference in melting even when pH was varied from pH 5.8 to pH 5.3 . The microstructure of the 0.6% calcium cheeses had an increase in protein folds and serum pockets. Low calcium cheeses had a very homogeneous structure. Directly acidified nonfat Mozzarella cheese manufactured with 1.0% dry salt and hot water stretching produced the best cheese. This cheese contained 0.4% salt, 0.4% calcium, no expressible serum, and good meltability.

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.

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.

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

A mussarela de leite de búfala, principal queijo obtido a partir desse leite no Brasil, é um produto praticamente novo no mercado, com alta aceitação pelos consumidores e excelentes perspectivas. Seguindo tecnologia de produção tradicional italiana, caracteriza-se pela intensa manipulação durante a sua elaboração. No presente trabalho, avaliou-se a qualidade microbiológica de duas marcas comerciais de queijo mussarela de leite de búfala, sendo uma das marcas comercializada em embalagem com soro (A) e a outra em embalagem sem soro e a vácuo (B), adquiridas no comércio varejista da cidade de Piracicaba/SP. As análises microbiológicas compreenderam a determinação do NMP de coliformes totais e fecais, a pesquisa de Listeria spp., a contagem de Staphylococcus coagulase-positiva e a pesquisa de Salmonella spp. Com base nos resultados obtidos, pode-se afirmar que as duas marcas analisadas encontram-se em acordo com os padrões microbiológicos legais vigentes. No entanto, pôde-se notar que a qualidade microbiológica dos queijos comercializados em embalagem com soro mostrou-se inferior à dos oferecidos ao consumo em embalagem sem soro e a vácuo. / Buffalo mozzarella cheese, main cheese obtained from buffalo milk in Brazil, is practically a recent product in the market, showing high acceptance by consumers and excellent perspectives. Following traditional italian production tecnology, this cheese is intensely manipulated during its manufacture. In this study, the microbiology quality of two commercial brands of buffalo mozzarella cheese was evaluated, being one of the brands presented in bag with whey (A) while the other one is presented in bag without whey and under vacuum (B). The samples were acquired in the Piracicaba city commerce. Microbiology analysis comprehended the determination of the MPN of total and fecal coliforms, the Listeria spp. presence / absence, the coagulase-positive Staphylococcus accounting and the Salmonella spp. presence / absence. Based on the analysis results, both brands are according to current legal microbiology standards specifications. However, the microbiology quality of the cheeses packed in bag with whey was lower than the microbiology quality of those offered in bag without whey and under vacuum.

Mozzarella cheese is currently the highest consumed cheese in the United States. The popularity of mozzarella cheese is typically attributed to the high consumption rates of pizza cheese and string cheese; both of which are low moisture part skim (LMPS) mozzarella cheese. A single serving of LMPS mozzarella cheese contains approximately 8% of the daily value (DV) for sodium, a mineral which is currently consumed in excess among most Americans. On average, one in three Americans has hypertension. This condition is strongly associated with excessive sodium intake, and it is a leading risk factor for cardiovascular disease and stroke in the United States. Considering the popularity of LMPS mozzarella cheese, its sodium content, and the alarmingly high rates of hypertension among the American population, mozzarella cheese appears to be a product worth pursuing for sodium reduction. Salt (NaCl) provides several key benefits to cheese including: flavor enhancement, preservation, moisture control, and syneresis; thus reducing its concentration in cheese can result in multiple quality concerns. Previous research has investigated the effects of lower sodium in a variety of cheeses including: cheddar, feta, and imitation cheese. Typical methods for reducing sodium content in cheese include reduction of NaCl alone to a level which is still acceptable or partial substitution of NaCl with salt replacers including KCl. For assessing the consumer acceptability of low sodium cheeses, researchers have typically employed the use of traditional hedonic, preference, and ranking questions; however, consumer scientists have recently suggested the benefits of asking consumers questions which go beyond typical acceptability questions. Purchase intent and decision making have been associated with consumer emotions, and perhaps by better understanding consumer emotions toward nutritional alternative foods, including low sodium mozzarella cheese, a more successful low sodium cheese can be developed. The current study implemented a series of tests to progressively understand the role NaCl plays in mozzarella cheese and consumer opinion of low sodium cheese. A series of traditional sensory tests, including triangle, duo-trio, and hedonic tests, were performed to determine a sensory transparent antimicrobial and a consumer acceptable salt replacer. Based upon this sequence of tests, a single antimicrobial (SEA-i F75) and concentration (0.275%) were selected in addition to the most consistently preferred salt replacer in a low sodium mozzarella cheese system; however, the most preferred salt replacer was dependent upon the type of mozzarella cheese (direct acid or bacteria cultured). In order to address the potentially limited information from traditional sensory testing, a novel method for evaluating emotions was developed. The IMET (Image Measurement of Emotion and Texture) method utilized consumer provided images of emotions, researcher generated emotion images, and emotion words (the current industry standard) to aid in emotion testing, and the use of texture images and texture words (industry standard) for texture assessment. The IMET method was tested and validated across three commercial food product categories: orange soda, dairy beverages, and convenience cheeses. The IMET study indicated consumer selected emotion images were less variable than emotion words in a positive emotion, but the words only method was less variable in a negative emotion. Additionally, subjects were more likely to use images of themselves for positive emotions, and images of others for the negative emotions. After validation of the IMET method, the consumer emotion images method was used in conjunction with consumer acceptability testing and instrumental texture analysis in non-commercial low sodium mozzarella cheese. This study indicated the full sodium cheese was consistently liked most, followed by the 100% KCl cheese sample. Additionally, cheese with higher hedonic scores had increased changes in the positive emotions, while the disliked products had increased changes in the negative emotions across the eating experience. The instrumental texture analysis resulted in significant textural differences between the eight samples tested, and samples with higher mean scores for all texture attributes were associated with having higher mean hedonic scores. The studies performed in this thesis are important contributions for better understanding the role of NaCl in LMPS mozzarella cheese, and the consumer’s perception and potential acceptance of this nutritional alternative product. Additionally, the development of a novel emotion testing method may impact how researchers ask consumer questions, conduct consumer research, and investigate the effects of images on emotion testing with consumers.

Submitted by Cláudia Bueno (claudiamoura18@gmail.com) on 2015-11-30T13:23:21Z No. of bitstreams: 2 Dissertação - Flávia Carneiro Gonçalves - 2015.pdf: 3718226 bytes, checksum: 3024f921d7aec7030599eee358d0593f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-12-01T06:45:31Z (GMT) No. of bitstreams: 2 Dissertação - Flávia Carneiro Gonçalves - 2015.pdf: 3718226 bytes, checksum: 3024f921d7aec7030599eee358d0593f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-12-01T06:45:31Z (GMT). No. of bitstreams: 2 Dissertação - Flávia Carneiro Gonçalves - 2015.pdf: 3718226 bytes, checksum: 3024f921d7aec7030599eee358d0593f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-07-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This study objectives to evaluate the effect of an inappropriate night cooling condition, it is practiced by some shops with processed mozzarella cheese and conventional mozzarella chemical profiles, using nuclear magnetic resonance technique (NMR). The simulation of inappropriate cooling was performed using a Styrofoam box with ice, not covered, and leaving the system to reach thermal equilibrium with the ambient temperature during the night. To make studies with processed mozzarella cheese was acquired two packages of the same batch, at local shops. Subjecting the spectral data, coming from the analysis made with HR-MAS, in the chemometric treatment was observed a tendency of discrimination in the samples exposed to different cooling conditions, and signals concerning lactose and some of fatty acids had greater influence in the observed separation. For the mozzarella cheese, in addition to NMR studies, it was also performed physical and chemical characteristics studies. For these studies, it has been acquired twenty-two trays containing sliced cheese, in the local market, which were divided into two sets with eleven trays each. Samples were analyzed in nature, using HR-MAS probe, and the crude extract using TBI probe. The identification of metabolites was done from the HSQC experiments, J-resolved and NMR ¹H, the last one being also used in the relative quantification of twelve metabolites. For the mozzarella cheese maintained under improper cooling conditions, there was a reduction in the galactose content and an increasing of amino acids and organic acids contents. The physicochemical analysis of pH, saturated fat and protein showed no significant differences that could be correlated with the different conditions of sample cooling. Finally, it has been concluded that NMR technique and chemometric tools are promising in identify the cheese samples submitted to different cooling conditions that has been studied, which could not be done using the physical and chemical parameters commonly used in cheese quality analysis. / Neste estudo vislumbrou-se avaliar a o efeito da condição de refrigeração noturna inadequada, praticada por alguns estabelecimentos comerciais, no perfil químico dos queijos tipo processados sabor mozarela e tipo mozarela convencional, fazendo uso da técnica de Ressonância Magnética Nuclear (RMN). A simulação da refrigeração inadequada foi realizada utilizando-se uma caixa de isopor contendo gelo, sem tampa, deixando o sistema atingir o equilíbrio térmico com o ambiente no decorrer da noite. Para os estudos com o queijo tipo mozarela processado adquiriu-se dois pacotes, pertencentes a um mesmo lote, no comércio local. Submetendo-se os dados espectrais, advindos das análises fazendo uso da sonda HR-MAS, ao tratamento quimiométrico, observa-se uma tendência de discriminação das amostras submetidas a diferentes condições de refrigeração, sendo que os sinais referentes a lactose e de alguns ácidos graxos tiveram maior influencia na separação observada. Já para o queijo tipo mozarela convencional, além dos estudos de RMN, realizou-se também estudos de características físico-químicas. Para isso, foram adquiridas no comércio local vinte e duas bandejas contendo queijo fatiado, as quais foram divididas em dois conjuntos com onze bandejas cada. Foram realizadas análises da amostra in natura, fazendo uso da sonda HR-MAS, e do extrato bruto, fazendo uso da sonda TBI. A identificação de metabólitos foi feita a partir dos experimentos HSQC, J-resolved e RMN de ¹H, sendo este último utilizado também na quantificação relativa de doze metabólitos. Para o queijo tipo mozarela mantido sob condições inadequadas de refrigeração observou-se uma redução no teor de galactose e aumento no teor de aminoácidos e ácidos orgânicos. As análises físicoquímicas de pH, gordura total e proteína total não mostraram diferenças significativas que pudessem ser correlacionadas com as diferentes condições de refrigeração das amostras. Nesse sentido, conclui-se que a técnica de RMN e ferramentas quimiométricas mostraram-se promissoras na identificação das amostras de queijo submetidas às diferentes condições de refrigeração estudadas, o que não pôde ser feito utilizando-se os parâmetros físico-químicos rotineiramente empregados em análises da qualidade de queijos.

A mussarela de leite de búfala, principal queijo obtido a partir desse leite no Brasil, é um produto praticamente novo no mercado, com alta aceitação pelos consumidores e excelentes perspectivas. Seguindo tecnologia de produção tradicional italiana, caracteriza-se pela intensa manipulação durante a sua elaboração. No presente trabalho, avaliou-se a qualidade microbiológica de duas marcas comerciais de queijo mussarela de leite de búfala, sendo uma das marcas comercializada em embalagem com soro (A) e a outra em embalagem sem soro e a vácuo (B), adquiridas no comércio varejista da cidade de Piracicaba/SP. As análises microbiológicas compreenderam a determinação do NMP de coliformes totais e fecais, a pesquisa de Listeria spp., a contagem de Staphylococcus coagulase-positiva e a pesquisa de Salmonella spp. Com base nos resultados obtidos, pode-se afirmar que as duas marcas analisadas encontram-se em acordo com os padrões microbiológicos legais vigentes. No entanto, pôde-se notar que a qualidade microbiológica dos queijos comercializados em embalagem com soro mostrou-se inferior à dos oferecidos ao consumo em embalagem sem soro e a vácuo. / Buffalo mozzarella cheese, main cheese obtained from buffalo milk in Brazil, is practically a recent product in the market, showing high acceptance by consumers and excellent perspectives. Following traditional italian production tecnology, this cheese is intensely manipulated during its manufacture. In this study, the microbiology quality of two commercial brands of buffalo mozzarella cheese was evaluated, being one of the brands presented in bag with whey (A) while the other one is presented in bag without whey and under vacuum (B). The samples were acquired in the Piracicaba city commerce. Microbiology analysis comprehended the determination of the MPN of total and fecal coliforms, the Listeria spp. presence / absence, the coagulase-positive Staphylococcus accounting and the Salmonella spp. presence / absence. Based on the analysis results, both brands are according to current legal microbiology standards specifications. However, the microbiology quality of the cheeses packed in bag with whey was lower than the microbiology quality of those offered in bag without whey and under vacuum.