Research of the technology of production of black and green tea extracts with antioxidant activity: determination of the effect of the extraction temperature

Many factors can influence the efficiency of the extraction of antioxidants from plants. The most important parameters that affect extraction efficiency in terms of yield and quality include temperature, extraction time, and particle size. The aim of our study was to select the optimal extraction temperature for two types of tea, to obtain extracts with high values of total phenols, flavonoids, antiradical activity according to the DPPH method, restoring strength according to the FRAP method and tannins. The objects of the study were extracts of two types of tea, obtained using one type of solvent - water, a grinding degree of 0.5 mm and three extraction temperatures of 20-25 °C, 40-50 °C and the boiling point of the solvent. A large amount of phenols is extracted from black tea extracts (493 mg (HA) / 100 g) with a temperature equal to the boiling point of the solvent, green tea (936 mg (HA) / 100 g) shows high values of phenol content at an extraction temperature of 40-50 (С. High values of the total content of flavonoids were observed at a temperature equal to the boiling point of the solvent in both black (456 mg (K) / 100 g) and green (502 mg (K) / 100 g) tea. The most tannins were found in extracts of black (98.3 mg catechin / 100 g) and green (224.9 mg catechin / 100 g) tea at a temperature of 40-50 °C. The lowest antiradical activity was found in extracts of black (Ec50 = 1.6 mg / cm3) and green (Ec50 = 4.0 mg / cm3) tea with an extraction temperature of 40-50 °C. The highest index of restorative power was in extracts of black (14.04 mmol Fe2+ / kg) tea with an extraction temperature equal to the boiling point of the solvent, and in green (12.15 mmol Fe2+ / kg) tea at a temperature of 40-50 (С.