Main parameters and the dynamics of volatile compounds during the fermentation of Chinese Mao-tofu from Huangshan region.

The physico-chemical parameters and kinetics of the volatile compounds during the fermentation of Chinese Mao-tofu was investigated. The levels of water soluble proteins, amino nitrogen and acidity increased gradually throughout the fermentation process, while that of reducing sugars peaked after 2 days before gradually declining. The protease activity increased significantly and reached the maximum levels at day 3, then it slightly decreased. The hardness and firmness decreased during the first 3 days, but both increased subsequently. The viscosity and adhesiveness was inversely related to the hardness and firmness. Forty-four volatile compounds were identified and quantified. Correlation analysis revealed significant correlation of the content of water soluble proteins and amino nitrogen with most volatile compounds. Acidity levels were positively correlated with that of ethyl caproate and hexyl alcohol, and negatively with 2-methyl butyric acid, palmitic acid, ethyl laurate, 1-octen-3-ol and 1-nonanol. Reducing sugar content was also positively correlated with ethyl caproate.