Optimization of Aeration Time in the Development Theaflavin-3,3’-Digallate Rich Black Teas

Samuel Kimutai,Augustine Muthiani,Stephen Karori,Thomas Kinyanjui,John Wanyoko,Francis Wachira

doi:10.4236/ajps.2015.619295

Abstract

This study involved the selection of 11 cultivars out of 201 screened cultivars of fresh green and purple coloured tea leaves for use in the manufacture of black teas with optimized antioxidant activities. Individual cultivars containing a combination of high leaf concentrations of the catechin fractions; epicatechin gallate (ECG) and epigallocatechin gallate (EGCG) were used in the processing of theaflavin-3,3’ digallate (TF3) rich black tea. The black tea enrichment with TF3 was carried out through optimization of the processing conditions of each cultivar by varying the aeration times between 0 min and 80 min at an interval of 20 min. The differently processed teas were then assayed for the TF3 contents. The data analysis was carried out using the GENSTAT at p ≤ 0.05. The optimal processing time for Ejulu, TRFK 832/8, TRFK 831/11, TRFK 824/1, SC 31/37, SC 12/28, K-Purple and TRFK 6/8 was found to be 60 min while that of TRFK 301/6, TRFK 301/3 and TRFK 655/1 was 40 min. The optimal TF3 levels were found to range from 0.19% to 0.60%.

Highlights

Black tea is the second most consumed beverage in the world after water [1]
This reaction enables the polymerization of catechins to form theaflavins (TFs) and thearubigins (TRs), a group of homogenous substances, responsible for the yellowish brown coloration in black tea beverage [6] [7]
The black tea samples processed at each of the aeration times were characterized for their TF3 levels to ascertain the aeration time at which their contents were maximal

Summary

Introduction

Black tea is the second most consumed beverage in the world after water [1]. Since its introduction in Kenya. The manufacturing process in black involves weathering the leaves to reduce moisture content, and macerating them to initiate oxidation by an enzyme known as polyphenol oxidase This reaction enables the polymerization of catechins (one of the major polyphenolic compounds in tea) to form theaflavins (TFs) and thearubigins (TRs), a group of homogenous substances, responsible for the yellowish brown coloration in black tea beverage [6] [7]. Eleven different tea cultivars (green and purple leaf) endowed with high levels of EGCG and ECG in a ratio of 1:1 were selected for use as raw materials in the processing of TF3 rich black teas. They were transferred into a cool box containing ice packs (to preserve catechins) and delivered to the miniature factory for processing

Black Tea Enrichment with TF3

Quantification of TF3 and Other TF Fractions

Data Analyses

Results and Discussion

Conclusion