Comparative evaluation of the impact of processing methods in determining the levels of health promoting chemical constituents and quality of green tea

Abstract

The first step of green tea manufacture involves enzyme deactivation by heat application. The present study investigated the effects of various fixing and processing methods viz. steam-roasting (S-6), pan-firing (P-8), blanching (B-2), and CTC cuts after steam-roasting (S-CTC), on the bio-chemical profiles and organoleptic quality of green teas processed differently into orthodox and CTC types, from region-specific tea cultivars, suitable for green tea production under agroclimatic condition of Dooars, West Bengal, India. Differences in fixing method and processing style showed notable variation (p ≤ 0.05) in the chemical quality indicators of green tea viz. Total catechin, polyphenol, flavonoid, and water extract content among the differently processed green teas. The most significant finding of the study revealed that when B-2 is employed for deactivation, it resulted in a substantial reduction (47%−52%) of caffeine levels without affecting the catechins content and antioxidant potential of green tea samples when compared to S-6 and P-8 methods. Interestingly, our results demonstrated significantly higher water extract values (42.19% dry weight) in green CTC teas and lower values in B-2 green tea samples (33.67%), as compared to S-8 and P-8 green teas, which received better taster ratings (≥ 7). These findings have highlighted the role of processing method and the impact of fixing technique in determining the contents of health-promoting attributes and taste quality of green teas, thus providing diverse choices to tea producers and consumers to opt for specific green tea products and expediting the need to further explore its commercial application in the nutraceutical and pharmaceutical industry (Supplemental Fig. S1).

Keywords

• processing
• constituents
• quality
• green-tea
• biochemicals
• ctc
• orthodox