Influence of manufacturing system scale for commercial Japanese green tea (Sencha) production on biochemical characteristics of tea leaf and infusion

Abstract

Dried green tea leaves (Sencha) were manufactured using various scale manufacturing systems, which processed batch‐wise for 15 kg (15 K), 60 kg (60 K), and 120 kg (120 K) fresh leaves. Total polyphenol content (TPC) and antioxidant activity (FRAP and DPPH) of dried tea leaves and infusions were evaluated. The values of TPC, FRAP, and DPPH of dried tea leaves processed by the larger systems (120 K and 60 K) were significantly higher than the values by the smaller system (15 K). In contrast, with the larger system scale, some of the leaves were not fully rolled and were not mechanically damaged during processing. These incomplete processing conditions led to the extraction of significantly fewer polyphenols in hot water, which might influence the health benefits of green tea infusions. This study indicated that there could be an optimal system scale that considers the balance between economic and health benefits, involving the optimization of production quality/amount. Practical Applications After harvest, Japanese green tea leaves are gradually dried using batch‐wise processing systems. The processing system scale is permanently fixed by the size of one batch, which is selected according to the circumstances of the production area and demand for tea production. However, tea leaf producers have experientially been aware of the quality variations in the final tea products, depending on the system scale. In this study, the impact of the scale of the manufacturing system on the functional properties of green tea was investigated. The results revealed that the hot water extract of dried tea leaves processed by a larger system scale tended to have less functional properties than those by a smaller system. This was due to the comparatively incomplete rolling conditions of tea leaves processed by larger manufacturing systems. These differences influence the preservability and extractability of the chemical components of the green tea leaves. Our findings provide beneficial information regarding processing conditions for better functional green tea infusions.