Changes of some bioactive and physicochemical properties during the black tea processing

In this research, some physical and bioactive properties of tea samples collected from every processing stage of black tea production were investigated. The processing stages were significantly effective on the investigated properties (moisture content, color parameters [L^* , a^* , and b^* ], and pH values the total phenolic substance, antioxidant activity) (p < 0.01). The antioxidant activities were found to be at a high level in fresh tea but decreased during the processing stages. Furthermore, the lowest activity was observed in the drying stage for extracts prepared with water and in the drying and sorting stages for extracts prepared with ethanol. In addition, it was determined that palmitic acid, myristic acid, and capric acid as saturated fatty acids, oleic acid, heptadecenoic acid, and eicosenoic acid as unsaturated fatty acids formed the fatty acid profile. Palmitic acid was determined to be the dominant fatty acid in tea samples. PRACTICAL APPLICATION: Tea is a beverage known to have positive health effects. The chemical structure of tea is very effective in providing these positive effects on health. Black tea production takes place in five stages in general terms (withering, rolling, oxidation, drying, and sorting stages) after the harvesting. These processes are very effective in the quality properties of tea. This research provides information about effects of processing stages on black tea. Our results demonstrate that processing was significantly effective on the physicochemical and bioactive properties of tea. Functionality of bioactive compounds could be maintained by optimization of the applied processes.