Effects of processing methods on quality, antioxidant capacity, and cytotoxicity of Ginkgo biloba leaf tea product

Ginkgo biloba leaves contain beneficial flavonoids, bilobalide (BB), and ginkgolides. However, the toxic ginkgolic acid (GA) limit its application. In this study, various traditional processing methods were used to prepare G. biloba leaf tea (GBLT), including white tea, black tea, dark tea, green tea, and freeze-dried as control, followed by investigations of their effects on quality, antioxidant capacity, bioactive components, and cytotoxicity of the tea products.

Results showed that different processing methods significantly impact the tea products' quality indexes and the principal component analysis (PCA) and hierarchical cluster analysis (HCA) corroborated it. White tea had the highest total sugar (TS) and GA content and the most potent cytotoxicity on HepG2 cells. However, TS and GA content and the cytotoxicity of GBLT markedly decreased during fermentation and fixation. Moreover, white tea possessed higher total phenolic content (TPC), total flavonoid content (TFC), and more vigorous antioxidant activities than green tea, black tea, and dark tea. Terpene trilactones value was stable, but different catechins contents fluctuated according to the manufacturing process of different GBLTs. Among the four GBLTs, dark tea combining fixation and fermentation had the lowest GA content and cytotoxicity, less bioactive components reduction, appropriate quality, and stronger flavor.

These findings demonstrate that fixation and fermentation help reduce GAs during the manufacturing of GBLT. However, their ability to retain bioactive substances needs further optimization in future studies. © 2023 Society of Chemical Industry.