Spatial changes in leaf biochemical profile of two tea cultivars following cold storage under two different vapour pressure deficit (VPD) conditions

摘要

Withering is considered a crucial stage of black tea processing. In this study, tea shoots from two cultivars (cvs. Yabukita and Clone 2) were stored at 5 degrees C, in either a low or high vapour pressure deficit (VPD) environment, to determine the impact of different withering rates on physiology (viz. respiration rate [RR], colour and moisture loss) and biochemical profile (viz. individual catechins, methylxanthines) of tea shoots (Camellia sinensis). Low VPD and high VPD conditions during withering increased caffeine levels in Clone 2 and Yabukita, respectively (p 0.05). Caffeine levels steadily increased over time in both cultivars (p 0.05), coinciding with a rapid decline in theobromine (TB). Furthermore, stems contained lower epigallocatechin gallate (EGCG) and caffeine (ca. 75 and 56%, respectively) compared to bud and larger leaf (LL) (p 0.05). Overall, the results of this study highlight factors such as mechanical harvesting, and hard or soft withering, which could affect final tea beverage quality.