The Implications of Post-Harvest Storage Time and Temperature on the Phytochemical Composition and Quality of Japanese-Styled Green Tea Grown in Australia: A Food Loss and Waste Recovery Opportunity

James Krahe,Michelle A Krahe,Nenad Naumovski

doi:10.3390/beverages7020025

James Krahe, Michelle A Krahe + Show 1 more

Open Access

https://doi.org/10.3390/beverages7020025

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Abstract

The increases in consumer awareness of the potential health benefits of green tea have driven global demand for green tea products. This study investigated the effect of post-harvest processing and storage of Japanese-styled green tea (Camellia sinensis var. sinensis) grown in NSW, Australia. Harvested material underwent a processing delay of 6, 12, 18 or 24 h at temperatures of 0, 5 and 25 °C. Targeted green tea constituents: theanine, caffeine and catechins were determined using HPLC with UV detection. Product quality and commercial value were determined using the Quality Index (QI) Tool. Reductions in constituent levels were evident within all storage delays, with nominal quality preservation achieved by reducing the temperature. The green tea material stored at 25 °C for 24 h created the most commercially valued product, despite it having visual characteristics more akin to a semi-fermented tea. These visual characteristics are traditionally considered markers of green tea damage and are discarded; however, QI-Tool scoring suggests that this raw material presents as a commercially favourable source of food loss and waste (FLW). The findings of this study extend our understanding of post-harvest processing delays and storage on green tea quality and suggest the viability of a commercially valuable semi-fermented produced from FLW.

Highlights

The conversion of freshly harvested green tea obtained from Camellia sinensis var. sinensis, into Japanese-styled green teas (i.e., Sencha and Gyokuro) is a lucrative export market for several countries [1,2]
The green tea samples used in the current study were Camellia sinensis var. sinensis plants grown on the New South Wales, Central Coast of Australia
The raw green tea material quality was highest and most biochemically concentrated when it was freshly harvested from the plant

Summary

Introduction

The conversion of freshly harvested green tea obtained from Camellia sinensis var. sinensis, into Japanese-styled green teas (i.e., Sencha and Gyokuro) is a lucrative export market for several countries [1,2]. After the harvest of tea, PPO initiates oxidization of the catechins and chlorophyll complexes This reaction results in the formation of tannins and other products of fermentation and oxidation that typically characterize common tea varieties such as ‘semi’ or ‘completely fermented’ tea (i.e., oolong or black tea varieties) [5,6,7]. This process, resulting in the darkening of the leaves and stems, changes the overall phytochemical composition and alters the organoleptic profile of the final tea product

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