热处理乳清蛋白对凝固型酸乳凝胶品质的影响

为研究热处理后的乳清蛋白对凝固型酸乳品质的影响,以添加热变前乳清蛋白的凝固型酸乳为对照,采用质构仪对凝固型酸乳的质构特性进行测定,分析筛选出恰当的热变程度的乳清蛋白,应用质构仪与流变仪进一步研究不同热变乳清蛋白添加量、不同糖添加量对凝固型酸乳的质构特性和流变特性的影响,结合电镜扫描,观察其微观结构,选出品质较优的酸奶。结果表明,酸奶中添加0.30%经72 ℃,15 min热处理的变性乳清蛋白和7%白砂糖,制得的凝固型酸乳凝胶的硬度为(263.4±11.85) g,粘附性为(413.2±15.33) g·sec,其微观结构与其他凝固型酸乳凝胶相比,空隙明显更小且分布更均匀,形成的网络结构更为规则、紧密和均一。这说明此热处理条件下的乳清蛋白可作为一种食品添加剂,对生产优质强化型酸奶具有重要的实际意义和借鉴价值。

Effect of Heat-treat Whey Protein on the Gel Quality of Set Yogurt

To investigate the effect of thermal treated whey protein on the quality of set yogurt,the texture analyzer was used to determine the gel texture of set yoghurt by adding coagulation yoghurt with pre-heat whey protein as a control,and found out the heat-induced whey protein with the proper degree. Using the texture analyzer and rheometer to research the effect of different heat-changed whey protein addition amounts and different sugar additions on the texture and rheological properties of set yoghurt. And combined with electron microscopy,the microscopic structure of set yogurt was observed to elect the better quality set yogurt. The results showed that adding 7% sugar and 0.30% thermal treated whey protein,which had been heated at 72 ℃ for 15 min,in the yogurt,the hardness of the prepared yogurt gel was(263.4±11.85) g,and the adhesiveness was(413.2±15.33) g·sec,and which the microstructure was significantly smaller and more evenly distributed compared with other set yogurt,the resulting network structure was more regular,compact and uniform. This showed that whey protein under this heat treatment conditions could be used as a food additive,which would have a important practical significance and reference value for the production of high-quality fortified yogurt.