A total of 853 milk samples with different phenotypes of $ kappa$-casein ($ kappa$-CN) and $ beta$-lactoglobulin ($ beta$-LG) and different preheating temperatures of 30, 70, 75 and 80$ sp circ$C were used for the making of individual laboratory scale Cheddar type cheese and for the determination of coagulating properties. Data obtained from milk input, cheese output and chemical analyses were used to calculate actual, 37% moisture adjusted and Van Slyke's theoretical yields and yield efficiency. Least squares analyses of data indicated that higher 37% moisture adjusted yields and yield efficiencies were obtained with milk types VII, VIII and IX, which have the B gene for $ kappa$-CN when compared to milk types I, II and III, which have the A gene for $ kappa$-CN irrespective of preheating temperatures. Moisture adjusted yield, 10.49%, was the highest when milk type VII containing $ kappa$-CN BB and $ beta$-LG AA phenotypes was preheated at 30$ sp circ$C, whereas milk type IX, which has phenotype BB for $ kappa$-CN and BB for $ beta$-LG, had the highest adjusted yields with values of 11.36, 11.91 and 11.99% when preheated at 70, 75 and 80$ sp circ$C, respectively. When cheese was made from milk preheated at 30$ sp circ$C, total solids (64.19%), fat (35.31%) and protein (25.82%) were highest in cheese obtained from milk types IX, VII and IX, respectively, all of which have the B gene for $ kappa$-CN. These three components (61.54%, 30.85% and 24.47%) were lowest in cheese made from milk types III, III and I, respectively, all of which have the A gene for $ kappa$-CN. Cheese with moisture content close to 39% were produced by milk types I and II preheated at 30$ sp circ$C. by milk types III, IV, V, VI, VII and VIII preheated at below 70$ sp circ$C and by milk type IX preheated at below 75$ sp circ$C. (Abstract shorted by UMI.)

A total of 596 milk samples with varying fat (3.0 to 4.0%) and protein (3.0 to 4.0%) contents were used to make laboratory-scale cheese and to determine coagulating properties. Higher levels of fat and protein in milk were associated with higher cheese yield. Milk protein has greater effect on cheese yield than milk fat. Adjusted yield increased by 1.91 and 1.29% for every percentage increase in the protein and fat of milk, respectively. Higher levels of fat in milk produced a cheese containing higher fat content and lower protein content. Similarly, higher levels of protein in milk produced higher protein content and lower fat content of cheese. Higher protein to fat ratio (or casein to fat ratio) in milk was associated with better efficiency of fat retention in the cheese. Casein retention in the cheese was not affected by the levels of fat and protein, or protein to fat ratio in milk. Milk adjusted for fat and protein resulted in delayed coagulation and a significant decrease in the curd firmness when compared with unadjusted bulk tank milk having the same levels of the two components.

Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Physiology, 1981. / Typescript (photocopy).

O leite instável não ácido (LINA) caracteriza-se pela perda da estabilidade da caseína ao teste do etanol, sem apresentar acidez acima de 18 °D. Este tipo de leite não é transportado para a indústria devido à subjetividade e imprecisão do teste do etanol, o qual não diferencia os tipos de leite, sendo eles: leite normal, LINA e o leite ácido. Este trabalho teve como objetivo contribuir para a compreensão dos fenômenos físico-químicos envolvidos na estabilidade e instabilidade das micelas de caseína em LINA e leite estável bovino e, desenvolver testes alternativos para a identificação e diferenciação de leite estável, ácido e LINA. Para este estudo foram utilizadas 58 vacas da raça Jersey e 130 vacas da raça Holandês em lactação. Teste de mastite subclinica para os animais da raça Jersey revelou 67% de positividade. O principal agente microbiano isolado do leite foi o Staphylococcus coagulase positivo. Não foi evidenciada relação entre a mastite subclínica e o LINA. Os atributos químicos do leite apresentaram diferenças significativas entre as raças avaliadas, independente da estabilidade do leite. Animais com períodos de lactação mais longos apresentaram maior instabilidade da caseína independente da raça estudada. Quanto a acidez, pH, contagem de células somáticas e contagem de bactérias totais não houve diferenças significativas para a estabilidade e raças avaliadas. O LINA apresentou todos os parâmetros avaliados dentro dos padrões exigidos pela legislação brasileira e não apresentando variações significativas com o leite estável. Testes de estabilidade em distintas concentrações de etanol mostrou que 72% (v/v) de etanol diferenciam claramente leite estável e o LINA. Leite estável e LINA apresentaram estabilidade térmica, mostrando que os dois testes não estão correlacionados. O perfil eletroforético das proteínas de leite estável e LINA não apresentou diferenças evidentes, indicando que a instabilidade não está associada a modificações qualitativas ou quantitativas nas caseínas do leite. Os resultados da análise de cálcio e fósforo total, micelar e solúvel, indicaram que o teor de cálcio na fração solúvel é consideravelmente maior no LINA, evidenciando que o cálcio iônico pode ser um fator importante na estabilidade do leite. Além disso, a relação Ca/P foi de 1,1/1 e 1,6/1 em leite estável e LINA, respectivamente. O maior teor de cálcio em relação ao fósforo no LINA pode contribuir para a sua desestabilização da micela de caseína na presença de etanol. O presente estudo deu origem a uma patente de invenção e sistema logístico para coleta de leite, a fim de evitar desperdícios indevidos e interpretações equivocadas acerca do tipo de leite. Particularmente, os métodos patenteados permitem que sejam realizados testes em campo que identificam e diferenciam de forma rápida e eficiente as amostras de leite estável, LINA e leite ácido. / Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2015-07-15T18:53:51Z No. of bitstreams: 1 Tese Lelis Aparecida Petrini Fontoura.pdf: 162872 bytes, checksum: ba234bd6702c33d0a239b0d5b99ca17b (MD5) / Made available in DSpace on 2015-07-15T18:53:51Z (GMT). No. of bitstreams: 1 Tese Lelis Aparecida Petrini Fontoura.pdf: 162872 bytes, checksum: ba234bd6702c33d0a239b0d5b99ca17b (MD5) / Universidade de Caxias do Sul, UCS. / The unstable non-acid milk (UNAM) is characterized by the instability of caseins in the ethanol test and low acidity (≤ 18 °D). This kind of milk is not transported to the industry due to the subjectivity and low precision of the ethanol test, which is not able to differenciate normal (stable), UNAM, and acid milk. The objective of the present work was to contribute for the understanding of the physic-chemical fenomena involved in the stability and instability of the casein micela in UNAM and stable bovine milk, and to develop reliable tests for the identification and diferenciation of stable, unstable, and acid milks. This study included 58 Jersey and 130 Holland cows in lactation. The subclinical mastitis test of Jersey animals resulted in 67% positivity. The most prevalent microbial agent isolated from subclinical mastitis milks was coagulase-positive staphylococci. It was not evidence any relation between subclinical mastitis and UNAM. Significant differences were detected between Jersey and Holland milks, but these were not related with milk stability. Animals with longer lactation period showed highest frequency of UNAM, independent of cow´s race. No significant differences for pH, acidity, somatic cell count, and total bacterial count, were detected between races and stable milk and UNAM. The UNAM showed all the parameter within the patterns stablished by Brazilian legislation, with not significant differences from stable milks. Stability tests in different ethanol concentrations showed that 72% (v/v) ethanol clarely discriminated UNAM and stable milk. Both UNAM and stable milk exhibited the same behavior at high temperatures, indicating that ethanol and thermal stability are not correlated. No differences were detected between the protein electrophoretic profile of stable milk and UNAM, indicating that the instability is not associated with qualitative or quantitative modification of milk caseins. The analysis of total, micelial and soluble calcium and phosphorus showed that calcium concentration in the soluble fraction is higher in UNAM than in stable milk, indicating that ionic calcium can be an important factor in milk stability. Moreover, Ca/P relation was 1.1/1 and 1.6/1 in stable milk and UNAM, respectively. The highest Ca/P relation in UNAM can contribute for the destabilization of the casein micela in the presence of ethanol. The present study originates an invention patent for the evaluation of milk stability, and a logical system for milk transport, that can reduce losses by the correct determination of milk quality. The patented method allows the rapid and efficient identification and differenciation of stable, UNAM and acid mik in the rural property and industry.

O leite instável não ácido (LINA) caracteriza-se pela perda da estabilidade da caseína ao teste do etanol, sem apresentar acidez acima de 18 °D. Este tipo de leite não é transportado para a indústria devido à subjetividade e imprecisão do teste do etanol, o qual não diferencia os tipos de leite, sendo eles: leite normal, LINA e o leite ácido. Este trabalho teve como objetivo contribuir para a compreensão dos fenômenos físico-químicos envolvidos na estabilidade e instabilidade das micelas de caseína em LINA e leite estável bovino e, desenvolver testes alternativos para a identificação e diferenciação de leite estável, ácido e LINA. Para este estudo foram utilizadas 58 vacas da raça Jersey e 130 vacas da raça Holandês em lactação. Teste de mastite subclinica para os animais da raça Jersey revelou 67% de positividade. O principal agente microbiano isolado do leite foi o Staphylococcus coagulase positivo. Não foi evidenciada relação entre a mastite subclínica e o LINA. Os atributos químicos do leite apresentaram diferenças significativas entre as raças avaliadas, independente da estabilidade do leite. Animais com períodos de lactação mais longos apresentaram maior instabilidade da caseína independente da raça estudada. Quanto a acidez, pH, contagem de células somáticas e contagem de bactérias totais não houve diferenças significativas para a estabilidade e raças avaliadas. O LINA apresentou todos os parâmetros avaliados dentro dos padrões exigidos pela legislação brasileira e não apresentando variações significativas com o leite estável. Testes de estabilidade em distintas concentrações de etanol mostrou que 72% (v/v) de etanol diferenciam claramente leite estável e o LINA. Leite estável e LINA apresentaram estabilidade térmica, mostrando que os dois testes não estão correlacionados. O perfil eletroforético das proteínas de leite estável e LINA não apresentou diferenças evidentes, indicando que a instabilidade não está associada a modificações qualitativas ou quantitativas nas caseínas do leite. Os resultados da análise de cálcio e fósforo total, micelar e solúvel, indicaram que o teor de cálcio na fração solúvel é consideravelmente maior no LINA, evidenciando que o cálcio iônico pode ser um fator importante na estabilidade do leite. Além disso, a relação Ca/P foi de 1,1/1 e 1,6/1 em leite estável e LINA, respectivamente. O maior teor de cálcio em relação ao fósforo no LINA pode contribuir para a sua desestabilização da micela de caseína na presença de etanol. O presente estudo deu origem a uma patente de invenção e sistema logístico para coleta de leite, a fim de evitar desperdícios indevidos e interpretações equivocadas acerca do tipo de leite. Particularmente, os métodos patenteados permitem que sejam realizados testes em campo que identificam e diferenciam de forma rápida e eficiente as amostras de leite estável, LINA e leite ácido. / Universidade de Caxias do Sul, UCS. / The unstable non-acid milk (UNAM) is characterized by the instability of caseins in the ethanol test and low acidity (≤ 18 °D). This kind of milk is not transported to the industry due to the subjectivity and low precision of the ethanol test, which is not able to differenciate normal (stable), UNAM, and acid milk. The objective of the present work was to contribute for the understanding of the physic-chemical fenomena involved in the stability and instability of the casein micela in UNAM and stable bovine milk, and to develop reliable tests for the identification and diferenciation of stable, unstable, and acid milks. This study included 58 Jersey and 130 Holland cows in lactation. The subclinical mastitis test of Jersey animals resulted in 67% positivity. The most prevalent microbial agent isolated from subclinical mastitis milks was coagulase-positive staphylococci. It was not evidence any relation between subclinical mastitis and UNAM. Significant differences were detected between Jersey and Holland milks, but these were not related with milk stability. Animals with longer lactation period showed highest frequency of UNAM, independent of cow´s race. No significant differences for pH, acidity, somatic cell count, and total bacterial count, were detected between races and stable milk and UNAM. The UNAM showed all the parameter within the patterns stablished by Brazilian legislation, with not significant differences from stable milks. Stability tests in different ethanol concentrations showed that 72% (v/v) ethanol clarely discriminated UNAM and stable milk. Both UNAM and stable milk exhibited the same behavior at high temperatures, indicating that ethanol and thermal stability are not correlated. No differences were detected between the protein electrophoretic profile of stable milk and UNAM, indicating that the instability is not associated with qualitative or quantitative modification of milk caseins. The analysis of total, micelial and soluble calcium and phosphorus showed that calcium concentration in the soluble fraction is higher in UNAM than in stable milk, indicating that ionic calcium can be an important factor in milk stability. Moreover, Ca/P relation was 1.1/1 and 1.6/1 in stable milk and UNAM, respectively. The highest Ca/P relation in UNAM can contribute for the destabilization of the casein micela in the presence of ethanol. The present study originates an invention patent for the evaluation of milk stability, and a logical system for milk transport, that can reduce losses by the correct determination of milk quality. The patented method allows the rapid and efficient identification and differenciation of stable, UNAM and acid mik in the rural property and industry.

No description available.

No description available.

No description available.

No description available.

β-lactoglobulin (β-Lg), bovine serum albumin (BSA), α-lactalbumin (α-Lac), and β-casein were adsorbed onto silanized silica surfaces of low and high hydrophobicity for 8 h, and β-Lg and BSA for 1 h. The surfaces were incubated in buffer for 0, 5, 10, or 15 h and then contacted with Listeria monocytogenes for 3 h. Cell adhesion was quantified using image analysis. Following 8 h of protein contact, adhesion to both surfaces was greatest when β-Lg was present and lowest when BSA was present. Preadsorption of α-Lac and β-casein showed an intermediate effect on cell adhesion. Adsorption of β-Lg for 1 h resulted in lower numbers of cells adhered as compared to the 8 h adsorption time, while the opposite was observed with BSA, but adhesion to BSA was observed to decrease slowly with film age to values comparable to the 8 h tests. The adsorption of BSA and β-Lg to both surfaces was also carried out where each protein was allowed to contact the surface in sequence and simultaneously. In sequential tests performed with an 8 h contact/protein, cell numbers on each surface were near that expected for the bare hydrophobic surface when β-Lg contact preceded introduction of BSA, whereas adhesion was reduced to values below that expected for the bare hydrophilic surface when BSA preceded β-Lg contact. In short-term sequential tests (1 h contact/protein), adhesion was lower than that recorded on bare hydrophilic surfaces in each case. Adhesion to each surface following contact with an equimolar mixture of β-Lg and BSA was lower than that measured on the bare hydrophilic surface in each case, with adhesion following 1 h contact being greater than that following 8 h contact. Adhesion following competitive adsorption was greater to hydrophobic than to hydrophilic surfaces. These results were explained with reference to the surface passivating character of BSA, and its ability to rapidly attain a nonexchangeable state upon adsorption, relative to β-Lg. / Graduation date: 1995