Influence and Optimization of Long-Time Superfine Grinding on the Physicochemical Features of Green Tea Powder

Abstract

Superfine grinding is a crucial step in green tea powder (GTP) processing. In this work, the time-resolved changes of physicochemical properties (physical properties, main active components, etc.) of GTPs were investigated, and ball milling time (BMT) for tea grinding was optimized. Variable importance in projection was used to evaluate the importance of modification of each physicochemical parameter on BMT, and multi-objective fuzzy optimization model was used to obtain the optimal BMT. The results showed that BMT had a significant influence on the physicochemical properties of GTP. Mean particle size and color difference of GTP dramatically correlated with BMT and could be described by one-phase exponential decay function. The optimal BMT was 18 h and high quality GTP could be obtained under this condition with small particle size, bright green color and rich in theanine and total tea polyphenols.

Keywords: Green tea powder, Superfine grinding, Physicochemical properties, Ball milling time, Optimization