Abstract The impacts of stirring and homogenisation processes on the physicochemical and sensory characteristics of stirred yoghurt produced from fresh, refrigerated and frozen/thawed sheep milk were studied. Yoghurt from frozen/thawed milk was more sensitive to post acidification and had a higher Casson yield stress than yoghurt from fresh milk. The main differences caused by stirring and homogenisation were observed in NIR backscattering and in rheological parameters of yoghurt from refrigerated and frozen/thawed milk (Casson yield stress reduced and Casson consistency index increased). These modifications, however, were not able to improve the low scores of sensory evaluation of yoghurt from frozen/thawed milk, probably penalised by their worst textures. Results suggest that sheep milk cold preservation, mainly freezing/thawing, negatively affects the characteristics of yoghurt; although some improvements in physicochemical parameters are observed after stirring and homogenisation, these were not enough to avoid poor sensory evaluation of the samples.

中文翻译：

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搅拌和均质过程是否能够改善用新鲜、冷藏和冷冻/解冻羊奶生产的搅拌酸奶的物理化学和感官特性？

摘要 研究了搅拌和均质过程对新鲜、冷藏和冷冻/解冻羊奶制成的搅拌酸奶的理化和感官特性的影响。与来自新鲜牛奶的酸奶相比，来自冷冻/解冻牛奶的酸奶对后酸化更敏感，并且具有更高的 Casson 产量压力。在 NIR 背向散射和来自冷藏和冷冻/解冻牛奶的酸奶的流变参数中观察到搅拌和均质引起的主要差异（Casson 屈服应力降低，Casson 稠度指数增加）。然而，这些修改无法改善来自冷冻/解冻牛奶的酸奶的感官评估的低分，这可能会受到其最差质地的影响。结果表明，羊奶冷藏，主要是冷冻/解冻，对酸奶的特性产生负面影响；尽管在搅拌和均化后观察到物理化学参数的一些改善，但这些还不足以避免对样品进行不良的感官评价。