抗冻剂对冷冻面团中酵母冷冻保护机理研究

Research on Freeze Protection Mechanism of Antifreeze for Yeast in Frozen Dough

研究了外源海藻糖、脯氨酸、甘油及其复合制剂对冷冻面团中酵母冷冻保护机理。采用气相色谱-质谱连用(GC-MS)检测面包酵母冷冻前后脂肪酸成分的变化,发现经冷冻后空白、2%海藻糖(2%T)、2%脯氨酸(2%P)、3%甘油(3%G)和2%海藻糖+2%脯氨酸+3%甘油(TPG)组酵母细胞中不饱和脂肪酸的种类、相对含量均增加,抗冻剂组比空白组增加幅度大,TPG组达到最高69.58%;-30℃冷冻7 d后,细胞蛋白含量明显增加,2%P组表达的蛋白量最多。通过SDS-PAGE凝胶电泳发现,酵母细胞在低温胁迫下会产生多种不同分子质量蛋白来抵御冷冻伤害,2%G和TPG组产生的蛋白种类最多。用透射电镜观察到低温冷冻、解冻会严重损伤酵母超微结构,抗冻剂对细胞超微结构均有不同程度的冷冻修复作用,修复后的细胞壁变厚、胞质均匀。

This study explored the freeze protection mechanism of exogenous trehalose ,proline,glycerin and itscompound preparation about the yeast which was in the frozen dough. Detect the change of the fatty acid compositionof unfrozen and frozen baker＇s yeast by a gas chromatography - mass spectrometry （ GC - MS）. Finding that, relativecontent and species of unsaturated fatty acids in the all groups （blank, 2% trehalose （2% T）, 2% proline （2% P）,3% glycerol （3%G） and 2% trehalose ＋2% proline ＋2% TPG） were increased after freezing. The more in-creased content was in antifreeze groups than the blank group. What＇ s more, the relative content of unsaturated fattyacids was the highest in the TPG group, reaching 69.58%. After 7d frozen under -30℃, the protein content in theyeast ceils increases significantly, especially the group of 2% P. Through SDS - PAGE gel electrophoresis, findingthat yeast cells under low temperature stress could produce a variety of different molecular weight protein, especiallythe groups of 2% G and TPG. Freezing and thawing could severely damage ultra - structure of yeast by transmission e-lectron microscope （TEM）, antifreeze had the different degrees repairing function for ultra - structure of cell, thancell wall turns thicken after repaired, and cytoplasm turns uniform.