Assessing biochemical changes during standardization of fermentation time and temperature for manufacturing quality black tea

Abstract

In black tea manufacturing, one of the most important steps is fermentation which influences the quality of tea. The macerated tea leaves were fermented at various temperatures (20, 25, 30, 35 °C) for different duration. Changes in polyphenoloxidase and peroxidase activities, depletion patterns of individual catechins, differences in individual theaflavin levels and formation of thearubigins were measured in leaves during fermentation. Higher stability of polyphenoloxidase and peroxidase enzymes was observed at lower temperature (20 °C), and increase in temperature, led to enzyme instability. The rate of degradation of all the catechins was found to be fastest at 35 °C and slowest at 20 °C. The formation and depletion of individual theaflavins varied with temperature and fermentation duration. The time required for the formation of maximum total theaflavins (TF) was highest at lower temperature and this time duration also varied for different theaflavins formation. Maximum amount of thearubigins (TR) content and liquor colour development was observed at 35 °C, and decrease in temperature reduced thearubigins accumulation. However, maximum brightness as well as TF/TR ratio was obtained at 20 °C, which suggests that fermentation at lower temperature is suitable for manufacturing quality black tea.

Analysis and modeling of major polyphenols during oxidation in production of black tea

“…Figures and show the effect of temperature and bed thickness on depletion of catechins (EGCG, ECG, EGC, and EC) during oxidation of CTC and orthodox leaves. The rates of catechin oxidation increased with the increase in air temperature, may be due to higher activity of PPO and PO at high temperature, as reported by Samanta et al (). Amount of EGCG is maximum in green leaf (nonoxidized sample) of TV25 clone, followed by EGC, ECG, and EC.…”

The effect of bacteria-based formulations on tea (Camellia sinensis L.) growth, yield, and enzyme activities

“…On the other hand, these enzymes are desirable in the process of black tea production, and can catalyse the transformation of catechin to thea avins (TF) and thearubigins (TR), responsible for the typical avour and colour of black tea [Jiang 2008]. The roles of PPO and PO in transforming catechin compounds to TF and TR have also been highlighted, and this has direct bearing on the quality of black tea [Samanta et al 2015]. Both of the oxidative enzymes PPO and POD are of considerable importance in black tea processing and for the quality and avour of the tea.…”

Optimization of Total Phenolics Content and Total Antioxidant Activity of Black Tea Using Response Surface Methodology

“…Reference [18] reported that with increase in temperature, the stability of enzyme decreased during fermentation and at 35 °C it can only be observed 90% stability of polyphenoloxidase up to 40 min. This decrease in polyphenoloxidase activity during fermentation could explain the increase in total phenolics content observed after fermentation beyond 38 °C for more than 1 h since polyphenoloxidase oxidizes the phenolic compounds.…”