This work reports a detailed study of the effect of ultrafiltration (UF) and diafiltration (DF) on the acid-induced gelation behavior of fresh milk retentates (2× and 4×). Concentrates were heated at 80°C for 15 min, and compared to unheated samples. The use of extensive DF caused a significantly greater amount of protein (both caseins and whey proteins) in the supernatant fraction, compared to UF retentates at the same concentration, both in unheated and heated samples. DF retentates showed higher pH of gelation, compared to the corresponding UF retentates. The development of tan δ is reported for the first time as a function of colloidal calcium release, and the protein gelation behavior discussed in light differences in composition of the soluble fraction. The results demonstrate how processing history can affect compositional changes and the gelation behaviour of fresh milk retentates. Membrane filtration is a widespread unit operation in the dairy industry, employed either to prepare fresh concentrates for further processing, or ingredients with specific functional properties. This work describes in detail the effect of processing history during membrane filtration on the rheological properties of acid induced gels and will help in optimizing formulations and prepare the right ingredients for the right application. It will also be possible to determine new ways to define processing quality of the milk protein concentrates, as it relates to their ability to form texture in fermented dairy products. This article is protected by copyright. All rights reserved.

中文翻译：

---

膜过滤浓缩脱脂乳的酸诱导凝胶行为

这项工作详细研究了超滤 (UF) 和渗滤 (DF) 对新鲜牛奶滞留物（2×和 4×）酸诱导凝胶行为的影响。浓缩物在 80°C 下加热 15 分钟，并与未加热的样品进行比较。与相同浓度的 UF 滞留物相比，在未加热和加热的样品中，大量 DF 的使用导致上清液部分中蛋白质（酪蛋白和乳清蛋白）的含量显着增加。与相应的 UF 滞留物相比，DF 滞留物显示出更高的凝胶 pH 值。tan δ 的发展首次被报道为胶体钙释放的函数，并在可溶部分组成的光差异中讨论了蛋白质凝胶行为。结果表明加工历史如何影响新鲜牛奶滞留物的成分变化和胶凝行为。膜过滤是乳制品行业中广泛使用的单元操作，用于制备用于进一步加工的新鲜浓缩物或具有特定功能特性的成分。这项工作详细描述了膜过滤过程中的加工历史对酸诱导凝胶流变特性的影响，并将有助于优化配方并为正确的应用准备正确的成分。还可以确定定义乳蛋白浓缩物加工质量的新方法，因为这与它们在发酵乳制品中形成质地的能力有关。本文受版权保护。版权所有。