黑木耳多糖凝固型酸奶发酵工艺优化

Optimization of Fermentation Process of Set Yogurt with Auricularia auricular Polysaccharide

以黑木耳多糖(Auricularia auricular polysaccharide,AAP)和纯牛奶为原料,嗜热链球菌、保加利亚乳杆菌和干酪乳杆菌组成的混合菌为发酵剂,研究AAP凝固型酸奶的最佳发酵工艺。以感官评价为指标,单因素实验探究蔗糖添加量、AAP添加量、明胶添加量、发酵时间、发酵温度、发酵剂接种量对AAP凝固型酸奶的影响,进一步采用响应面试验设计对AAP凝固型酸奶的发酵工艺进行优化,并对其酸奶品质进行评价。结果表明:AAP固体酸奶的最佳发酵工艺参数为0.33%明胶、7.0%蔗糖、3.0%发酵剂、0.1%AAP、发酵时间6.9 h、发酵温度42℃。在此最优工艺下进行验证实验,得到的AAP凝固型酸奶的感官评分为(9.30±0.08)分,与预测值吻合;将其与普通酸奶的感官评分(8.83±0.12)分、持水力(63.83%±2.69%)和质构特性比较,AAP酸奶的持水力(72.14%±3.58%)和质构特性显著提高,感官评分更优;此外,AAP酸奶的游离氨基酸和胞外粗多糖显著(P<0.05)升高,脂肪含量(2.35±0.25 g/100 g)显著(P<0.05)低于普通酸奶(4.16±0.39 g/100 g),具有更高的营养价值和保健功效。因此,AAP凝固型酸奶具备开发成为一种新型功能性酸奶的潜力。

Auricularia auricular polysaccharide(AAP)and pure milk were used as raw material. The mixture of Streptococcus thermophiles,Lactobacillus bulgaricus and Lactobacillus casei were selected as starter culture to investigate best fermentation process of AAP setyogurt. With sensory evaluation as the index,effects of sucrose content,AAP contents,gelatin contents,fermentation time,fermentation temperature and fermentation agent contents on sensory evaluation of AAP set yogurt were studied by single experiments. Furthermore,response surface test was used to optimize the fermentation process parameters of AAP set yoghurt,and the yoghurt quality was analyzed. The results showed that the optimal technological parameters of AAP set yoghurt were gelatin 0.33%,sucrose 7.0%,fermentation agent 3.0%,AAP 0.1%,fermentation time 6.9 h and fermentation temperature 42 ℃. Under this optimal process,the sensory scores of AAP set yogurt was(9.30±0.08) score in the validation experiment,which was consistent with the predicted value. Compared with the sensory scores(8.83±0.12 score),water holding capacity(63.83%±2.69%)and texture characteristics of common yoghurt,the AAP set yoghurt had higher water-holding capacity(72.14%±3.58%)and texture characteristics,which result in better sensory scores. In addition,the free amino acids and extracellular crude polysaccharides of AAP yogurt significantly increased. And the fat contents(2.35±0.25 g/100 g)of AAP yogurt was significantly lower than that of common yogurt(4.16±0.39 g/100 g). It indicated that AAP set yogurt had higher nutritional value and health care function. Therefore,AAP set yogurt had the potential to develop into a new type of functional yogurt.