Optimization of Fermentation Technology of Daqu Mulberry Leaf Tea by Response Surface Method and Principal Component Analysis

In order to study the quality of daqu-multi-strain coupling-fermentation mulberry leaf tea, the amount of daqu inoculum, initial sugar content, fermentation temperature and leaf water content were used as the technological indexes to study the effects of different technological parameters on the flavonoids, amino acids, total phenols and sensory quality of mulberry leaf tea. The optimal process was determined by response surface-principal component analysis. The results showed that the optimum conditions for the fermentation of mulberry leaf tea were 65% leaf water content, 8% daqu inoculum, 6% initial sugar content, 30 ℃ fermentation temperature, and 0.996±0.02 standardized synthesis score, which was close to 1.0105±0.01 theoretical normalization synthesis score. Under these conditions, the contents of flavonoids, amino acids and total phenols in fermented mulberry leaf tea were 35.81, 1.38 mg/g and 16.68 mg/g, respectively. In this study, the fermentation process of mulberry leaf tea was optimized by response surface-principal component analysis (RSA-PCA), which provided certain data support for the development and utilization of mulberry leaf tea.