Fonterra Research and Development Centre, Private Bag 11029, Dairy Farm Road, Palmerston North, New Zealand.
Fonterra Research and Development Centre, Private Bag 11029, Dairy Farm Road, Palmerston North, New Zealand.
Food Chem. 2015 May 1;174:339-47. doi: 10.1016/j.foodchem.2014.11.054. Epub 2014 Nov 14.
Milk was heated at different pH (pH 6.5-7.1) and temperatures (20-120 °C/10 min). This resulted in different levels of casein and denatured whey proteins to be distributed between the colloidal and serum phases. The milks were subsequently acidified and the distribution of protein between colloidal and serum was monitored at different pH. On acidification to pH 5.4, the serum phase caseins and denatured whey proteins partially reassociated with the caseins, although a complex behaviour was observed at ∼ pH 5.4 where additional casein dissociation occurred in some samples. At pH below 5.4 the caseins and denatured whey proteins rapidly aggregated. No separate aggregation of κ-casein/denatured whey protein complexes or κ-casein depleted micelles was observed. The earlier gelation of milks heated at higher pH was likely to be due to the destabilisation of the entire milk protein system rather than a preferential aggregation of the serum phase proteins.
牛奶在不同的 pH 值（6.5-7.1）和温度（20-120°C/10 分钟）下加热。这导致不同水平的酪蛋白和变性乳清蛋白在胶体和血清相之间分布。随后对牛奶进行酸化，并在不同 pH 值下监测蛋白质在胶体和血清之间的分布。在酸化至 pH 5.4 时，血清相中的酪蛋白和变性乳清蛋白部分与酪蛋白重新结合，尽管在约 pH 5.4 时观察到复杂的行为，因为在一些样品中发生了额外的酪蛋白解离。在 pH 值低于 5.4 时，酪蛋白和变性乳清蛋白迅速聚集。未观察到 κ-酪蛋白/变性乳清蛋白复合物或 κ-酪蛋白耗尽的胶束的单独聚集。在较高 pH 值下加热的牛奶较早凝胶化可能是由于整个牛奶蛋白质系统的不稳定，而不是血清相蛋白质的优先聚集。
