酸面团（sourdough）发酵技术可明显改善面包品质，使其具有独特风味，但我国暂未实现工业化酸面团面包生产，因此探索采用酸面团技术改善面包品质的机理及方法有助于提高其经济和社会效益。本项目申请人在前期的研究中筛选获得一株产香酵母Pichia kudriavzevii，该菌株发酵小麦粉酸面团能明显改善面包风味，采用低温发酵能进一步促进面包芯特征风味物质乙酸-2-苯乙酯积累，然而，国内外关于低温胁迫改善酸面团面包风味的研究尚无明确阐述。本项目拟对低温发酵条件下乙酸-2-苯乙酯及合成相关前体物质、关键酶酶活、蛋白表达及其基因转录水平的变化规律进行研究，明确低温发酵时乙酸-2-苯乙酯的主要合成途径，在此基础上结合生物信息学分析，系统阐明低温对P. kudriavzevii发酵小麦粉酸面团促进乙酸-2-苯乙酯合成的调控机制。通过本项目的实施，以期为低温胁迫下酸面团主要风味物质合成机制提供理论基础。

Sourdough fermentation technology can improve bread quality and present a unique flavor. However, China has not achieved the industrialized production of sourdough bread yet. Therefore, the exploration of the mechanisms and methods of using sourdough technology to improve bread quality can help improve the economy and get social benefits. The applicant of this project obtained an aroma-producing strain of Pichia kudriavzevii in the previous study. The strain used in wheat flour sourdough fermentation can significantly improve the bread flavor, and low-temperature fermentation can further promote the accumulation of 2-phenylethyl acetate, which is the characteristic flavor substance of the bread crumb. The researches on improving the sourdough bread aroma by low-temperature fermentation have not been elaborated. This project aims to uncover the main synthetic pathways of 2-phenylethyl acetate by studying the changes in 2-phenylethyl acetate and its synthesis-related precursors, key enzymes, protein expression and gene transcription levels under low-temperature fermentation. Based on these results and bioinformatics analysis, the regulation mechanisms of P. kudriavzevii during low-temperature wheat flour sourdough fermentation will be systematically elucidated. Through the implementation of this project, the results may provide a theoretical basis for the synthesis mechanisms of the main flavor substances in low-temperature fermented sourdough, and then provide technical parameters to improve the bread quality using sourdough fermentation technology in the future.