The thesis deals with the control of the weight of soft cheeses during molding on a manual line. The theoretical part describes the classification of cheeses into groups, the basic characteristics of soft cheeses and their representatives. Furthemore, the whole technology of soft cheese production is processed and the effects on curd formation and factors influencing the weight of cheeses during molding are explained. The theoretical part ends with the basics of statistics for data processing. Basic measuring techniques (dry matter measurement, pH measurement, measurement of temperature and weight) were selected to determine the technological parameters (pH of whey, pH, dry matter and temperature of cheese grain, weight of cheese etc.) to describe the quality of grain in the experimental part of the thesis. The Design of Experiments method was used to find the optimal setting of the molding machine. Three partial experiments were designed and done. Results were verified in real production. The pH of whey was chosen to describe the grain quality. Two factors have been discovered that have a significant effect on the weigh of cheeses during molding, namely the position of the operator during molding and the amount of whey flowing into the forms with the cheese grain. The proposed molding modifications were successfully tested in production and no statistical difference was found between the weight of cheeses formed with the new setting of molding machine.

Manufacture of white soft cheese from ultrafiltered whole cows• milk involved acidification of pasteurized homogenized whole milk to pH 6.0 with phosphoric or citric acid. The preacidified milk was ultrafiltered at 54 °C until 60% of original milk weight was removed as permeate, diafiltered with deionized water equal to 38.5% of the original milk and concentrated by UF (4.8 fold) to pre-cheese (38% total solid). The pre-cheese was heated to 76.7°C/16 sec, 71 .l°C/l6 sec (HTST) and 7l.l°C/l5 min (controlled water bath), inoculated with 2% starter culture (Streptococcus cremoris), renneted (10 ml/100 lb retentate) and placed in one pound plastic containers in which coagulation took place (8-10 min). Salt (1 .5%) was added on the top of parchment paper placed under the lid, and the curd was incubated at 85°F. The most acceptable cheese was from ultrafiltered retentate heated for 16 sec at 76.7°C before cheese making. Organoleptic tests showed that samples highest in calcium content ranked highest in acceptability. Acidification with citric acid removed more calcium than phosphoric acid and resulted in softer cheese than the control cheese (non-acidified). Slight bitterness was observed when excessive starter and low salt (NaCl) concentration were used. Addition of salt to the retentate prior to heating caused thickening of the retentate before 70°C was reached. Extending the heating time increased the tendency toward mealiness in the cheese.

This study investigated the manufacturing procedures and texture attributes of direct acid set of an unripened, shelf-stable cheese variety produced by the combined technologies of ultrafiltration and ultra-high temperature processing. Product evaluation included physical and chemical properties such as gel strength, syneresis, pH, moisture, protein, and fat. Whole milk was concentrated by ultrafiltration to 30, 35, and 40% total solids. Milk retentate was ultra-high temperature-processed by preheating to 65 or 77°C, sterilized at 141°C for 4 s by direct steam injection, flash cooled to approximately 62 or 72°C, homogenized in two stages at either 13.8/2.1 or 27.6/4.1 MPa, cooled to 38°C, and aseptically packaged. iv sterilized sodium chloride was aseptically added and dissolved in the ultra-filtrated and ultra-high temperature processed retentate to produce .5% final concentration. Autoclaved solutions of citric and lactic acids, or glucono-delta-lactone were added aseptically to the salted retentate to form a soft gel by lowering the pH range from 4.3 to 4.6. The coagulated retentates were stored at room temperature for 6 months. The effects of total solids, homogenization pressures, preheat temperatures, acidulants, and storage time on selected physicochemical properties of the acid gels were determined. Taste panels evaluated selected soft cheese characteristics after 6 months' storage. No statistically significant effect of the total milk solids level on gel firmness was observed. High homogenization pressure and the interaction of high preheat temperature and homogenization pressure produced significantly firmer gel and caused less syneresis. Acidulant types influenced significantly gel strength, syneresis, appearance, and texture. Soft cheeses prepared with citric acid were firmer than those acidified with lactic acid or gluconodelta-lactone. Lactic acid samples produced more syneresis than citric acid cheese samples. Cheese samples prepared with glucono-delta-lactone had the smoothest and least grainy texture, shiny appearance, little or no wheying-off, and a gel strength intermediate between the two other acidulants.

O objetivo desse estudo foi validar a aplicação da metodologia isotópica de identificação da origem dos gliceróis em gorduras presentes em requeijões e especialidades lácteas com o intuito de oferecer uma ferramenta de controle de qualidade, de fiscalização de mercado e detecção de fraudes. Para atingir esse objetivo, isolou-se o glicerol de compostos lácteos como requeijões, especialidades lácteas, leite e óleos vegetais (empregados como padrões de origem animal e vegetal, respectivamente) e aplicou-se a metodologia isotópica. O glicerol foi isolado através da centrifugação. Foram analisadas todas as marcas de requeijões e similares (28 marcas) disponíveis nos supermercados da cidade de Piracicaba, e depois, agrupadas conforme sua identificação: requeijão cremoso, especialidade láctea com requeijão cremoso, alimento à base de requeijão e creme vegetal, requeijão cremoso com amido e não identificado. Do total, cinco marcas apresentaram resultados com diferença significativa (p<0,05) quando comparados ao controle (padrão animal - leite). A metodologia isotópica permitiu identificar a origem do material analisado e detectar alterações nos padrões. Comprovou-se a eficácia da metodologia isotópica na identificação da origem da matéria graxa de requeijões e a aplicabilidade da técnica no controle de qualidade de lácteos, auxiliando tanto no recebimento de matéria-prima como de produto final. / The objective of this study was to validate the application of the isotopic methodology of identification of glycerol origin in the fat fraction of "requeijões" (Brazilian soft cheeses) and similar products aiming at the identification of a quality control instrument for market fiscalization and fraud detection. In order to pursue the specific objectives of this study, the glycerol was isolated from spreadable dairy products such as "requeijões" and others. Cow's milk and vegetable oils of known origins were adopted as standards. The isotopic methodology was applied to identify the origin of the carbon present in the glycerol molecule of the fats present in those foods. Glycerol was isolated according to a conventional based on centrifugation. Twenty-eight commercial brands of "requeijões" available in the supermarkets of Piracicaba city were classified according to the information provided in the lables and analyzed. Out of the total, 5 brands were significantly different (p<0,05) when compared to the control (animal pattern - milk), indicating absence of the milk fat in the formulation. The isotopic methodology allowed to identify the origin of the analyzed material and to detect alterations in the patterns. The effectiveness of the isotopic methodology in the identification of origin of the lipid constituents of "requeijão" was proven as well as the applicability of the technique in dairy industry quality control, both in the final product as well as in process supplies.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-19T12:28:29Z No. of bitstreams: 1 claudiaoliveirafontes.pdf: 4732336 bytes, checksum: b5385191fb0ea13de3e2e756b49d0981 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-06-29T12:22:06Z (GMT) No. of bitstreams: 1 claudiaoliveirafontes.pdf: 4732336 bytes, checksum: b5385191fb0ea13de3e2e756b49d0981 (MD5) / Made available in DSpace on 2017-06-29T12:22:06Z (GMT). No. of bitstreams: 1 claudiaoliveirafontes.pdf: 4732336 bytes, checksum: b5385191fb0ea13de3e2e756b49d0981 (MD5) Previous issue date: 2013-04-12 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste estudo, os padrões de susceptibilidade a antimicrobianos, ocorrência de marcadores moleculares de resistência aos antimicrobianos e biocidas, bem como as características de virulência associadas aos Staphylococcus spp., foram avaliados tanto em SCN quanto em S. aureus isolados de queijo Minas Frescal no Brasil. Um total de 246 isolados bacterianos foram recuperados de 35 amostras de queijo, as quais foram obtidas em cinco lotes de cada uma das sete marcas comerciais diferentes avaliadas neste estudo. As contagens bacterianas variaram de 103 a 107 UFC/g de queijo. Os percentuais elevados de resistência a antimicrobianos foram observados nos dois grupos bacterianos com relação à oxacilina, penicilina e eritromicina. Um percentual baixo de resistência aos antimicrobianos foi encontrado com relação ao cloranfenicol, e todas as bactérias avaliadas se mostraram susceptíveis à vancomicina e linezolida. No total, o índice de resistência múltipla aos antimicrobianos (MAR) > 0,2 foi observado em 80,6 % e 84,2 % dos isolados de SCN e S. aureus, respectivamente. Entretanto, o índice MAR variou de 50 % a 100 % considerando apenas os isolados bacterianos estudados por marca comercial de queijo. Com relação à prevalência de SCN e S. aureus que carregam o gene mecA, respectivamente, 81,5 % e 47,4 % das linhagens isoladas foram consideradas mecA+, e 76,2 % e 42,1 % destas se mostraram fenotipicamente resistentes à oxacilina. Três isolados bacterianos carregavam o gene para produção de enterotoxina A (sea), 30,5 % produziram biofilme em um teste de laboratório, e a α ou ß-hemólise foi observada em 2,8 % e 7,2 %, respectivamente, em todos os Staphylococcus spp. avaliados. Os marcadores moleculares de resistência aos antimicrobianos e biocidas mais prevalentes encontrados nas linhagens de SCN e S. aureus foram blaZ, mecA, msrA, msrB, linA, aacA-aphD, e smr. Este estudo destaca a importância do fenômeno da resistência aos antimicrobianos com relação aos microrganismos negligenciados que são veiculados por alimentos, e os prováveis riscos para a saúde pública relacionados ao consumo de queijo contendo bactérias do gênero Staphylococcus. / In this study, antimicrobial susceptibility patterns, molecular markers of antimicrobial and biocide-resistance occurrence and virulence-associated characteristics were evaluated in CoNS and S. aureus isolated from soft cheese in Brazil. A total of 246 bacterial isolates were recovered from 35 cheese samples belonging to five batches with seven different trademarks. The bacterial counts ranged from 103 to 107 CFU g1. High antimicrobial resistance percentages were observed for oxacillin, penicillin and erythromycin for both S. aureus and SCN. A low antimicrobial resistance percentage was observed for chloramphenicol, and all of the tested bacteria were susceptible to vancomycin and linezolid. In total, a multiple antibiotic resistance (MAR) index of > 0.2 was observed for 80.6 % and 84.2 % of the isolated CoNS and S. aureus, respectively. However, the MAR index ranged from 50 % to 100 % when only bacterial cheese isolates belonging to the same trademark were considered. Regarding to the prevalence of SCN and S. aureus carrying mecA gene, respectively, 81.5 % e 47,4 % of the isolated strains were mecA+, and 76.2 % and 42.1 % of these were phenotypically resistant to oxacillin. Three isolates carried the enterotoxin A gene (sea), 30.5 % produced biofilm in a laboratory test, and α- or ßhemolysis was observed for 2,8 % and 7.2 %, respectively, for all the Staphylococcus spp.. blaZ, mecA, msrA, msrB, linA, aacA-aphD, and smr were most prevalent molecular markers found both in SCN and S. aureus strains. This study highlights the extent of the antimicrobial resistance phenomenon in neglected foodborne microorganisms and the potential public health risks that are related to the consumption of Staphylococci-contaminated soft cheese.

O objetivo desse estudo foi validar a aplicação da metodologia isotópica de identificação da origem dos gliceróis em gorduras presentes em requeijões e especialidades lácteas com o intuito de oferecer uma ferramenta de controle de qualidade, de fiscalização de mercado e detecção de fraudes. Para atingir esse objetivo, isolou-se o glicerol de compostos lácteos como requeijões, especialidades lácteas, leite e óleos vegetais (empregados como padrões de origem animal e vegetal, respectivamente) e aplicou-se a metodologia isotópica. O glicerol foi isolado através da centrifugação. Foram analisadas todas as marcas de requeijões e similares (28 marcas) disponíveis nos supermercados da cidade de Piracicaba, e depois, agrupadas conforme sua identificação: requeijão cremoso, especialidade láctea com requeijão cremoso, alimento à base de requeijão e creme vegetal, requeijão cremoso com amido e não identificado. Do total, cinco marcas apresentaram resultados com diferença significativa (p<0,05) quando comparados ao controle (padrão animal – leite). A metodologia isotópica permitiu identificar a origem do material analisado e detectar alterações nos padrões. Comprovou-se a eficácia da metodologia isotópica na identificação da origem da matéria graxa de requeijões e a aplicabilidade da técnica no controle de qualidade de lácteos, auxiliando tanto no recebimento de matéria-prima como de produto final. / The objective of this study was to validate the application of the isotopic methodology of identification of glycerol origin in the fat fraction of "requeijões" (Brazilian soft cheeses) and similar products aiming at the identification of a quality control instrument for market fiscalization and fraud detection. In order to pursue the specific objectives of this study, the glycerol was isolated from spreadable dairy products such as "requeijões" and others. Cow's milk and vegetable oils of known origins were adopted as standards. The isotopic methodology was applied to identify the origin of the carbon present in the glycerol molecule of the fats present in those foods. Glycerol was isolated according to a conventional based on centrifugation. Twenty-eight commercial brands of "requeijões" available in the supermarkets of Piracicaba city were classified according to the information provided in the lables and analyzed. Out of the total, 5 brands were significantly different (p<0,05) when compared to the control (animal pattern - milk), indicating absence of the milk fat in the formulation. The isotopic methodology allowed to identify the origin of the analyzed material and to detect alterations in the patterns. The effectiveness of the isotopic methodology in the identification of origin of the lipid constituents of "requeijão" was proven as well as the applicability of the technique in dairy industry quality control, both in the final product as well as in process supplies.