| dc.description.abstract | Fuzhuan Brick Tea (FBT), has a long history in China and other regions. It is considered a special type of tea with health-promoting functions, including antioxidant, anti-inflammatory, anti-obesity, antibacterial, and anticancer activities. However, the origins and components of its unique flavor and various biological activities are still not fully understood. The predominant microorganism in FBT is Eurotium cristatum, a fungus, which is believed to be closely associated with the characteristics and functions of FBT. This microorganism can utilize the organic compounds in tea, producing various compounds and enhancing their bioavailability, including gallic acid. Gallic acid is an important antioxidant found in tea and possesses bioactive properties such as antioxidant and anti-inflammatory effects, which are beneficial to human health. Despite the potential benefits of FBT, there have been relatively few studies on the impact of fermentation conditions on the quality and functionality of FBT. Therefore, this study focuses on the effect of fermentation conditions on the content of gallic acid and antioxidant properties of E. cristatum-fermented tea.
The study is divided into two parts. The first part is isolating and screening the required strain, and Eurotium cristatus DK was successfully isolated and purified from FBT, identified as Aspergillus cristatus DUCC5705 through 16S rDNA analysis. The second part explores various fermentation conditions — the amount of tea powder added, the initial pH value, different carbon sources and additions, different nitrogen sources, and fermentation temperature, optimizing these conditions based on the production of gallic acid and antioxidant activity. The study successfully identifies the optimal fermentation conditions, which include adding 4% tea powder, initial pH of 4.0, 3% lactose, 3% malt extract, and fermentation temperature 30°C.
Experimental results show that the content of gallic acid in the fermented tea by E. cristatus DK can reach 0.22-0.29 g/g, equivalent to 5.5-7.25% of the dry weight of tea. This is higher than the gallic acid content found in Gallanut (2-4% dry weight). In summary, the fermentation of tea with E. cristatus DK shows a high conversion rate of gallic acid and produces a tea fermentation product with high biological activity. These research findings can be applied to the development of tea beverages and health food products. | en_US |