Study On The Fermentation And Volatile Flavor Of Red Bean Curd

The red bean curd is a kind of sufu, has a long history of production techniques, with strong local characteristics. Under the trend of modernization of traditional foods, this thesis studied the early fermentation conditions of red bean curd, tracked its fermentation process to discussed the different salt addition on chemical components and texture of sufu fermentation process, analyzed the volatile flavor components of the change process, and comparative analyzed the difference of volatile flavor components between red bean curd with commercially available type of bean curd, designed to establish a standardized red tofu manufacturing practices, reinforced the theoretical basis of the red bean curd, and also provided a reference for improving the quality of red bean curd.The early fermentation conditions of red bean curd were studied, the concentration of the bacterial suspension has a significant influence on the activity of protease. The optimum fermentation conditions: bacterial suspension concentration 3.2×107 / mL, fermentation time 42 h, fermentation temperature 26 ℃.The changes of chemical composition and texture in red bean curd during the post-fermentation process were investigated. Among them, the total acid content were increased; pH values were decreased; water-soluble protein content were increased, the amino nitrogen content was also a growing trend; while the hardness and the elasticity of red bean curd on post-fermentation process decreased gradually, and the viscosity increased gradually.Study on volatile flavor compounds in red fermented bean curd process shows that the relative content of aldehydes reduced from 69.5% to 7.92% after the fermentation of sufu. The alcohols were increased from 7.85% to 23.16%, the types and relative content of esters were also increased. With the extension of fermentation time, little changes on the substances species. The relative content of alcohols were reduced significantly, the esters were increased significantly.The comparative analysis on volatile flavor compounds between commercially available type of bean curd and homemade red bean curd were studied. 80,61,56,65 compounds were detected from different sufu, and there was a significant different among them. Among them, alcohol content was highest in red bean curd, the type and content of esters were higher, but ketones and aldehydes were lower. Methyl isovalerate, isovaleric acid ethyl ester, ethyl valerate, alpha pinene, limonene, incense tree ene were only detected in the red bean curd.