Metzger L E, Barbano D M, Rudan M A, Kindstedt P S, Guo M R
Northeast Dairy Foods Research Center, Department of Food Science, Cornell University, Ithaca, NY 14853, USA.
J Dairy Sci. 2000 Jan;83(1):1-10. doi: 10.3168/jds.S0022-0302(00)74847-8.
Whiteness (L-value) changes in low-fat and low-moisture, part-skim Mozzarella cheeses during heating (7 to 60 degrees C) and cooling (60 to 7 degrees C) were evaluated. In low-fat Mozzarella, a large increase in whiteness was observed during heating, and a decrease in whiteness was observed during cooling. In low-moisture, part-skim Mozzarella, the whiteness changes during heating and cooling were smaller. Serum phase was removed from low-fat and low-moisture, part-skim Mozzarella cheeses. White protein gels were formed when the isolated serum phase from either low-fat or low-moisture, part-skim Mozzarella was heated. The white gel that formed was composed predominantly of casein and casein proteolysis products. The gel might have been produced by heat-induced, hydrophobic protein-protein interactions, and it tended to dissociate when cooled. Formation of a gel during heating increased light scattering, which increased the L-value. The gel dissociated during cooling and no longer scattered light, which decreased the L-value. We hypothesized that a gel, which was reversible, formed in the serum phase of cheese during heating and might have been responsible for the observed changes in the L-value of low-fat Mozzarella cheese during heating and cooling. The additional fat in low-moisture, part-skim Mozzarella compared with low-fat Mozzarella masked some of the color changes in the serum phase of low-moisture, part-skim Mozzarella. A model was developed to describe the contributions of the casein matrix plus serum phase of Mozzarella cheese and the contribution of fat to the changes in whiteness of Mozzarella cheese during heating and cooling.
对低脂低水分半脱脂马苏里拉奶酪在加热（7至60摄氏度）和冷却（60至7摄氏度）过程中的白度（L值）变化进行了评估。在低脂马苏里拉奶酪中，加热过程中观察到白度大幅增加，冷却过程中白度下降。在低水分半脱脂马苏里拉奶酪中，加热和冷却过程中的白度变化较小。从低脂低水分半脱脂马苏里拉奶酪中去除了血清相。当加热来自低脂或低水分半脱脂马苏里拉奶酪的分离血清相时，会形成白色蛋白质凝胶。形成的白色凝胶主要由酪蛋白和酪蛋白水解产物组成。这种凝胶可能是由热诱导的疏水蛋白质 - 蛋白质相互作用产生的，冷却时倾向于解离。加热过程中凝胶的形成增加了光散射，从而增加了L值。冷却时凝胶解离，不再散射光，从而降低了L值。我们假设在加热过程中奶酪的血清相中形成了一种可逆的凝胶，这可能是低脂马苏里拉奶酪在加热和冷却过程中观察到的L值变化的原因。与低脂马苏里拉奶酪相比，低水分半脱脂马苏里拉奶酪中额外的脂肪掩盖了低水分半脱脂马苏里拉奶酪血清相中的一些颜色变化。开发了一个模型来描述马苏里拉奶酪酪蛋白基质加血清相的贡献以及脂肪对马苏里拉奶酪在加热和冷却过程中白度变化的贡献。
