Acharya M R, Mistry V V
MN-SD Dairy Foods Research Center, Dairy Science Department, South Dakota State University, Brookings 57007, USA.
J Dairy Sci. 2004 Dec;87(12):4004-12. doi: 10.3168/jds.S0022-0302(04)73541-9.
The objective of this study was to compare the effects of vacuum-condensed (CM) and ultrafiltered (UF) milk on some compositional and functional properties of Cheddar cheese. Five treatments were designed to have 2 levels of concentration (4.5 and 6.0% protein) from vacuum-condensed milk (CM1 and CM2) and ultrafiltered milk (UF1 and UF2) along with a 3.2% protein control. The samples were analyzed for fat, protein, ash, calcium, and salt contents at 1 wk. Moisture content, soluble protein, meltability, sodium dodecyl sulfate-PAGE, and counts of lactic acid bacteria and nonstarter lactic acid bacteria were performed on samples at 1, 18, and 30 wk. At 1 wk, the moisture content ranged from 39.2 (control) to 36.5% (UF2). Fat content ranged from 31.5 to 32.4% with no significant differences among treatments, and salt content ranged from 1.38 to 1.83% with significant differences. Calcium content was higher in UF cheeses than in CM cheeses followed by control, and it increased with protein content in cheese milk. Ultrafiltered milk produced cheese with higher protein content than CM milk. The soluble protein content of all cheeses increased during 30 wk of ripening. Condensed milk cheeses exhibited a higher level of proteolysis than UF cheeses. Sodium dodecyl sulfate-PAGE showed retarded proteolysis with increase in level of concentration. The breakdown of alphas1- casein and alphas1-I-casein fractions was highest in the control and decreased with increase in protein content of cheese milk, with UF2 being the lowest. There was no significant degradation of beta-casein. Overall increase in proteolytic products was the highest in control, and it decreased with increase in protein content of cheese milk. No significant differences in the counts of lactic starters or nonstarter lactic acid bacteria were observed. Extent as well as method of concentration influenced the melting characteristics of the cheeses. Melting was greatest in the control cheeses and least in cheese made from condensed milk and decreased with increasing level of milk protein concentration. Vacuum condensing and ultrafiltration resulted in Cheddar cheeses of distinctly different quality. Although both methods have their advantages and disadvantages, the selection of the right method would depend upon the objective of the manufacturer and intended use of the cheese.
本研究的目的是比较真空浓缩（CM）乳和超滤（UF）乳对切达干酪某些成分及功能特性的影响。设计了五种处理方式，包括来自真空浓缩乳（CM1和CM2）和超滤乳（UF1和UF2）的2种蛋白质浓度水平（4.5%和6.0%）以及一种蛋白质含量为3.2%的对照。在第1周时对样品的脂肪、蛋白质、灰分、钙和盐含量进行分析。在第1、18和30周时对样品进行水分含量、可溶性蛋白质、融化性、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）以及乳酸菌和非发酵乳酸菌计数。在第1周时，水分含量范围为39.2%（对照）至36.5%（UF2）。脂肪含量范围为31.5%至32.4%，各处理间无显著差异，盐含量范围为1.38%至1.83%，存在显著差异。超滤干酪中的钙含量高于CM干酪，其次是对照，且其随干酪乳中蛋白质含量的增加而增加。超滤乳制成的干酪蛋白质含量高于CM乳。所有干酪的可溶性蛋白质含量在成熟30周期间均增加。浓缩乳干酪的蛋白水解程度高于超滤干酪。SDS-PAGE显示随着浓度水平的增加，蛋白水解受到抑制。αs1-酪蛋白和αs1-I-酪蛋白组分的分解在对照中最高，且随干酪乳蛋白质含量的增加而降低，UF2最低。β-酪蛋白无显著降解。蛋白水解产物的总体增加在对照中最高，且随干酪乳蛋白质含量的增加而降低。在乳酸菌发酵剂或非发酵乳酸菌的计数方面未观察到显著差异。浓缩程度及方法影响了干酪的融化特性。对照干酪的融化性最大，浓缩乳制成的干酪融化性最小，且随乳蛋白质浓度水平的增加而降低。真空浓缩和超滤产生了质量明显不同的切达干酪。虽然两种方法都有其优缺点，但正确方法的选择将取决于制造商的目标和干酪的预期用途。
