Optimization of the Ball Milling Process for Producing Superfine Green Tea Powder: An Analytic Hierarchy Process–Fuzzy Comprehensive Evaluation Approach

In this study, the ball milling method was used to produce superfine green tea powder (SGTP). We used the contents of chlorophyll, caffeine, tea polyphenols, and total free amino acids as indicators and combined the analytic hierarchy process (AHP) and fuzzy comprehensive evaluation to establish an AHP-fuzzy comprehensive evaluation approach applicable to SGTP. The production process of SGTP was optimized using the response surface methodology (RSM). The results showed that the three factors of grinding time, rotation speed, and ball-to-material ratio had significant effects on the content of the main components of the tea powder, and the order of the effects was as follows: ball-to-material ratio > grinding time > rotation speed. The optimal grinding time, rotation speed, and ball-to-material ratio for the preparation of SGTP were 5.85 h, 397 r/min, and 9.2:1, respectively. We also found that, compared with green tea powder made with the traditional crushing method, the SGTP prepared under these conditions possessed strong advantages in terms of particle size, the content and dissolution of major components, and antioxidant capacity. In this study, the optimization of the production process of tea powder is initially discussed, and then, a new evaluation method for tea powder is proposed, providing technical support for improving the quality of green tea powder. The AHP-fuzzy comprehensive evaluation approach, by quantifying qualitative assessments, significantly refined our optimization process, enabling a more precise determination of optimal SGTP production parameters.