Warncke Malou, Kulozik Ulrich
Chair of Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University of Munich, Weihenstephaner Berg 1, 85354 Freising, Germany.
Foods. 2021 Jun 11;10(6):1361. doi: 10.3390/foods10061361.
Milk protein concentrate (MPC) and micellar casein (MC) powders are commonly used to increase the protein concentration of cheese milk. However, highly-concentrated milk protein powders are challenging in terms of solubility. The research question was whether and how incompletely dissolved agglomerates affect the protein functionality in terms of rennet gelation behavior. For the experiments, skim milk was enriched with either MC88 or MPC85 to a casein concentration of 4.5% (/) and sheared on a laboratory and pilot scale in rotor/stator systems (colloid mill and shear pump, respectively) and high-pressure homogenizers. The assessment criteria were on the one hand particle sizes as a function of shear rate, and on the other hand, the rennet gelation properties meaning gelling time, gel strength, structure loss upon deformation, and serum loss. Furthermore, the casein, whey protein, and casein macropeptide (CMP) recovery in the sweet whey was determined to evaluate the shear-, and hence, the particle size-dependent protein accessibility. We showed that insufficient powder rehydration prolongs the rennet gelation time, leading to softer, weaker gels, and to lower amounts of CMP and whey protein in the sweet whey.
乳蛋白浓缩物（MPC）和胶束酪蛋白（MC）粉末常用于提高奶酪生产用牛奶的蛋白质浓度。然而，高浓缩乳蛋白粉在溶解性方面存在挑战。研究问题是未完全溶解的团聚物是否以及如何根据凝乳酶凝胶化行为影响蛋白质功能。在实验中，脱脂奶用MC88或MPC85富集至酪蛋白浓度为4.5%（/），并分别在实验室规模和中试规模下，在转子/定子系统（分别为胶体磨和剪切泵）和高压均质机中进行剪切。评估标准一方面是作为剪切速率函数的颗粒大小，另一方面是凝乳酶凝胶化特性，即凝胶化时间、凝胶强度、变形时的结构损失和乳清损失。此外，测定了甜乳清中酪蛋白、乳清蛋白和酪蛋白巨肽（CMP）的回收率，以评估剪切作用以及因此与颗粒大小相关的蛋白质可及性。我们发现，粉末复水不充分会延长凝乳酶凝胶化时间，导致凝胶更软、更弱，甜乳清中的CMP和乳清蛋白含量更低。
