以海藻糖和鲜牛奶为主要原料,用保加利亚乳杆菌和嗜热链球菌的混合菌种作为发酵剂来研制海藻糖功能性酸奶。以海藻糖添加量、蔗糖添加量、接种量和发酵时间为因素,采用单因素和正交试验设计,根据感官评价和酸度、黏度来确定最佳配方和工艺参数,并采用固相微萃取气质联用技术对海藻糖酸奶和全蔗糖酸奶的挥发性风味物质进行测定;用质构仪对海藻糖酸奶及全蔗糖酸奶进行质构特性的测定。结果表明,海藻糖凝固型酸奶的最佳工艺配方为:5%海藻糖、4%蔗糖,4%接种量,在42 ℃下发酵4 h时酸奶的口感最佳;此外,在最佳工艺的条件下应用气相色谱质谱联用技术对海藻糖酸奶和普通蔗糖酸奶的挥发性风味物质进行差异性研究表明海藻糖酸奶中酮类物质和芳香杂环类物质集其他风味物质含量比全蔗糖酸奶要高。经过质构仪检测,两种酸奶在硬度、内聚力和弹性方面相差甚微,在黏附性与咀嚼性上稍有不同。
This experiment was developed with Trehalose and fresh milk as the main raw materials. Mixture of Lactobacillus bulgaricus and Streptococcus thermophilus was used as starter cultures to prepare trehalose functional yoghurt. The optimum formulation and technological parameters were determined by sensory and acid viscosity, the addition of trehalose, the amount of sucrose, the inoculum size and the time of fermentation. The volatile flavor compounds in the whole yoghurt were determined by solid-phase microextraction and GC-MS. The results showed that the optimum formula of trehalose yogurt with the best the taste after fermentation at 42 ℃ for 4 h was 5% trehalose, 4% sucrose, 4% inoculum. In addition, results from gas chromatography mass spectrometry under optimum conditions showed that the contents of ketones and aromatic heterocyclic compounds and other flavor substances in trehalose yogurt were higher than those of sucrose yoghurt. The texture parameters of these two kinds of yogurt were compared. They had little differences in hardness, cohesion and elasticity, and their adhesiveness and chewiness.