Regional features of the formation of the antioxidant properties of black tea

Abstract

The article considers the influence of the region of origin of black tea on the formation of its antioxidant properties. The study involved samples of black tea, coming to the retail trade of St. Petersburg from Indian, Ceylon, Chinese and Kenyan. Significant differences were found in the quantitative composition of individual antioxidants in black tea samples, depending on the region of growth, both in the dry tea leaf and in the infusion. Water-soluble extractives in dry tea leaves and infusion prevailed in Ceylon tea. Tannin prevailed in Indian tea, and total phenolic compounds and flavonoids in Kenyan. The maximum transition of tannins in the infusion occurred in Kenyan tea, which accounted for 97.9% of its content in dry tea leaves. The higher brewing temperature of black tea increased the extraction of individual antioxidants. Black tea, depending on the region of origin, was distributed according to the content of total phenolic compounds and flavonoids as follows: Kenyan tea samples > Chinese tea samples > Indian tea samples > Ceylon tea samples. The antioxidant properties of tea were studied for anti-radical activity by the DPPH method and chelation ability by the FRAP method. Chinese tea samples had the highest antiradical activity, and Kenyan tea samples had the ability to bind chelate compounds into complexes. The deviation of antioxidant properties between samples of black tea from different regions was a maximum of 10% in terms of chelating ability (FRAP method) and 35.5% in anti-radical activity (DPPH method). The maximum antiradical activity and chelating ability of all samples of black tea was indicated at a higher tea brewing temperature.