Effects of processing technologies on chlorogenic acid, gallic acid and theanine in selected Kenyan tea cultivars

Abstract

Tea (Camellia sinensis) is popular for its high levels of polyphenols which are attributed to its antioxidant properties. However, other associated biomolecules are also potent antioxidants and contribute to health effects. These include theanine which increases gamma-Aminobutyric acid (GABA) levels, serotonin and dopamine, thus reducing stress, relaxes the body and improves mood. Chlorogenic acid (CGA) which has antioxidant, anti-obesity, anti-atherosclerotic and anti-cancer properties; and Gallic acid (GA) has antioxidant and antimicrobial properties. A study was conducted to determine the variation of theanine, CGA, GA and with processing technologies including aeration and non-aeration coupled with Cut, Tear and Curl (CTC) and Orthodox maceration. Six (6) tea varieties including TRFK 6/8, TRFK 11/4, TRFK 12/2, TRFK 31/8, TRFK 54/40 and TRFK 306/1 were used. Profiling of theanine, CGA and GA was done using High Performance Liquid Chromatography and data analysis was done using SAS software (P=0.05). Chlorogenic acid ranged from 15.16 to 32.87% for green teas and 22.82 to 39.14% for black teas with the variety TRFK 12/2 registering least values and TRFK 306/1 the highest mean value. Galic acid values ranged from 0.28 to 0.51% for green teas and 0.28 - 0.55% for black teas with TRFK 6/8 registering the least content and TRFK 306/1 registering the highest amounts. Theanine range was highest in non-aerated teas at 0.97-1.82% and 0.79-1.47% for black teas with clone TRFK 6/8 registering the lowest level and TRFK11/4 the highest content. The research shows that theanine values in teas are best preserved through non-aeration processing, while CGA and GA values are enhanced by aeration processing.