Acid gels and yoghurts were made from goat milk that was heated at 72C/30 s, 85C/5 min and 95C/5 min, followed by acidification with starter culture at 43C until pH 4.6. The rheological and textural properties of acid gels and yoghurts were analyzed using dynamic low amplitude oscillatory rheology and back extrusion texture analysis, respectively. The effect of goat milk heat treatment on the mean casein micelle diameter and protein profile were also determined by dynamic light scattering (DLS) and SDS PAGE electrophoresis, respectively. The shortest gelation and fermentation time was recorded for yoghurt prepared from milk heated at 85C/5 min. Also, the pH of gelation, the storage moduli (G') and yield stress were higher for this yoghurt, compared with the other two. Textural properties of goat milk yoghurts such as firmness and consistency were strongly affected by milk heat treatment, and the highest values were recorded for yoghurt produced from milk preheated at 85C/5 min, as well. The largest casein micelles were measured after 85C/5 min treatment and their size decreased at higher temperature, despite higher denaturation of whey proteins at the most intense heat regime, indicating the structure changes that influence on the acid gelation. This article is protected by copyright. All rights reserved.

中文翻译：

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山羊奶热处理对酸凝胶和凝固型酸奶酪蛋白胶束大小、流变学和质地特性的影响

酸性凝胶和酸奶由山羊奶制成，以 72C/30 秒、85C/5 分钟和 95C/5 分钟加热，然后在 43C 下用发酵剂酸化至 pH 4.6。分别使用动态低振幅振荡流变学和反挤压质地分析来分析酸凝胶和酸奶的流变学和质地特性。山羊奶热处理对平均酪蛋白胶束直径和蛋白质分布的影响也分别通过动态光散射 (DLS) 和 SDS PAGE 电泳确定。最短的凝胶化和发酵时间被记录为由以 85C/5 分钟加热的牛奶制成的酸奶。此外，与其他两种酸奶相比，这种酸奶的凝胶化 pH、储能模量 (G') 和屈服应力更高。山羊奶酸奶的质地特性（例如硬度和稠度）受到牛奶热处理的强烈影响，并且记录了由以 85C/5 分钟预热的牛奶生产的酸奶的最高值。最大的酪蛋白胶束是在 85C/5 分钟处理后测量的，它们的大小在较高温度下减小，尽管在最强烈的加热状态下乳清蛋白的变性程度更高，表明结构变化会影响酸凝胶化。本文受版权保护。版权所有。尽管在最强烈的加热状态下乳清蛋白的变性程度更高，这表明影响酸凝胶的结构变化。本文受版权保护。版权所有。尽管在最强烈的加热状态下乳清蛋白的变性程度更高，这表明影响酸凝胶的结构变化。本文受版权保护。版权所有。