Riddet Institute, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand.
Riddet Institute, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand.
J Dairy Sci. 2022 May;105(5):3871-3882. doi: 10.3168/jds.2021-21444. Epub 2022 Mar 10.
The interactions among the proteins in sheep skim milk (SSM) during heat treatments (67.5-90°C for 0.5-30 min) were characterized by the kinetics of the denaturation of the whey proteins and of the association of the denatured whey proteins with casein micelles, and changes in the size and structure of casein micelles. The relationship between the size of the casein micelles and the association of whey proteins with the casein micelles is discussed. The level of denaturation and association with the casein micelles for β-lactoglobulin (β-LG) and α-lactalbumin (α-LA) increased with increasing heating temperature and time; the rates of denaturation and association with the casein micelles were markedly higher for β-LG than for α-LA in the temperature range 80 to 90°C; the Arrhenius critical temperature was 80°C for the denaturation of both β-LG and α-LA. The casein micelle size increased by 7 to 120 nm, depending on the heating temperature and the holding time. For instance, the micelle size (about 293 nm) of SSM heated at 90°C for 30 min increased by about 70% compared with that (about 174.6 nm) of unheated SSM. The casein micelle size increased slowly by a maximum of about 65 nm until the level of association of the denatured whey proteins with casein micelles reached 95%, and then increased markedly by a maximum of about 120 nm when the association level was greater than about 95%. The marked increases in casein micelle size in heated SSM were due to aggregation of the casein micelles. Aggregation of the casein micelles and association of whey protein with the micelles occurred simultaneously in SSM during heating.
绵羊脱脂乳（SSM）中的蛋白质在热处理（67.5-90°C，0.5-30 分钟）过程中的相互作用通过乳清蛋白变性的动力学和变性乳清蛋白与酪蛋白胶束的缔合，以及酪蛋白胶束的大小和结构的变化来表征。讨论了酪蛋白胶束的大小与乳清蛋白与胶束的缔合之间的关系。β-乳球蛋白（β-LG）和α-乳白蛋白（α-LA）的变性水平和与酪蛋白胶束的缔合随加热温度和时间的增加而增加；在 80 至 90°C 的温度范围内，β-LG 的变性和与酪蛋白胶束的缔合速度明显高于α-LA；β-LG 和α-LA 的变性的阿伦尼乌斯临界温度均为 80°C。酪蛋白胶束的大小增加了 7 至 120nm，这取决于加热温度和保持时间。例如，在 90°C 加热 30 分钟的 SSM 的胶束大小（约 293nm）比未加热的 SSM（约 174.6nm）增加了约 70%。在变性乳清蛋白与酪蛋白胶束的缔合水平达到 95%之前，酪蛋白胶束的大小通过最大约 65nm 的缓慢增加，在缔合水平大于约 95%之后，通过最大约 120nm 的显著增加。加热 SSM 中酪蛋白胶束大小的显著增加是由于胶束的聚集。在加热过程中，SSM 中的酪蛋白胶束聚集和乳清蛋白与胶束的缔合同时发生。
