Stability and chemical changes of phenolic compounds during Oolong tea processing

A study was conducted to investigate the impact of lightly fermented Oolong tea processing on the alteration of constituents, particularly phenolic compounds. Harvested tea shoots were immediately processed under strict processing control. Tea infusions brewed with each process unit operation were analyzed for total polyphenols, caffeine (CF), gallic acid (G) and catechin profiles. During processing, the contents of total polyphenols and CF significantly remained constant, while G significantly increased. The content of total catechins was slightly decreased, approximately 10% during the manufacture of Oolong tea from fresh tea shoots. Among the process unit operations, indoor withering, pan-firing and drying steps had impact on catechin concentrations. This result should be considered for tea manufacturing in order to maximize potential health benefits from catechins in Oolong tea. (C) All Rights Reserved