氨基酸触发馒头面团中甲基营养型芽孢杆菌芽孢萌发机制研究

拉丝变质是最常见和最难克服的馒头变质问题之一。前期试验表明，蒸制阶段未致死的甲基营养型芽孢杆菌芽孢在贮藏期间萌发是拉丝变质发生的根本原因，在馒头醒发阶段，外源氨基酸能诱导芽孢快速萌发，萌发的芽孢能被蒸汽完全杀死。上述提前发生的萌发过程为防治拉丝变质提供了新思路，但其触发机制尚不明确。本研究探讨氨基酸（种类及浓度）对面团醒发阶段芽孢萌发特性的影响，在此基础上，分析醒发条件（温度、含水量、酵母量及二次和面时间）对芽孢萌发特性的影响，明确促进芽孢萌发的最适氨基酸及面团醒发条件；采用单胞分析技术和蛋白组学分析氨基酸对面团醒发期间芽孢萌发差异性、形态学特性和差异表达蛋白的影响，揭示氨基酸触发馒头面团中甲基营养型芽孢杆菌芽孢萌发机制。本项目创新点在于首次深入研究氨基酸触发下固态食品中非模式菌株芽孢萌发机制，为“先萌发后致死”方法在馒头保鲜贮藏的应用提供理论基础，也将会有效地推动馒头商品化的发展。

Drawstring metamorphism is one of the most common and difficult problems in the metamorphism of room temperature steamed bread. In the early stage of steamed bread, the germinating of the non lethal of Bacillus methylotrophic spore during storage is the root cause of drawstring metamorphism. In the fermentation of steamed bread, exogenous amino acids can induce rapid germination of the spores, and the germinated spores can be completely killed by steam. The earlier germination process provided a new idea for the prevention and control of drawstring degeneration, but its triggering mechanism was not clear. In this study, the effects of amino acids (types and concentrations) on the germination characteristics of spores in the fermentation of dough were studied. On this basis, the effects of fermentation conditions (temperature, water content, yeast quantity and secondary dough mixing) on the germination characteristics of spores were analyzed, and the optimum amino acids and dough fermentation conditions for promoting germination were determined. The effects of amino acids on the germination difference, morphological characteristics and differential protein expression of spores during dough fermentation were analyzed by cell analysis and proteomics, so as to reveal the mechanism of amino acids triggering spore germination of Bacillus methylotrophic spore in steamed bread dough. The innovation of this project lies in the first in-depth study on the germination mechanism of non model strains in solid food triggered by amino acids, which will provide theoretical basis for the application of "germination first and then death" method in the preservation and storage of steamed bread, and will effectively promote the development of commercialization of steamed bread.