Optimization of fermentation technology of functional lotus leaf tea by response surface-principal component analysis

Using lotus leaf as raw material, a functional lotus leaf tea was prepared by fermentation with strong-flavor (Nongxiangxing) Daqu. Using the total flavonoids content, total phenols content and sensory score as evaluation indexes, the effect of Daqu inoculum, fermentation time and temperature, initial sugar content on the quality of the functional lotus tea were analyzed by single factor tests and the response surface method-principal component analysis. The results showed that the optimal fermentation conditions were Daqu inoculum 8%, fermentation time 30 h, temperature 27 ℃, and initial sugar content 9%. Under the optimal conditions, the functional lotus leaf tea had strong flavor and unique taste, and the total flavonoids, total phenols contents and sensory score in functional lotus leaf tea were 30.17 mg/g, 73.51 mg/g and 96.2 points, respectively. This study provided a theoretical basis for the application of lotus leaf.