Yuwan Wang1, Mingyue Zhang1, Zhengzhu Zhang1, Hengqian Lu2, Xueling Gao1, Pengxiang Yue1,3. 1. State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, Anhui, China. 2. School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China. 3. Damin Foodstuff (Zhangzhou) Co. Ltd, Zhangzhou, Fujian, China.
Abstract
BACKGROUND: Theabrownins (TB) are bioactive components that are usually extracted from Chinese dark tea, in which they are present at low concentrations. The present study aimed to produce an instant dark tea high in theabrownins via submerged fermentation by the fungus Aspergillus niger. Three fermentation parameters that affect theabrownins content (i.e. inoculum size, liquid-solid ratio and rotation speed) were optimized using response surface methodology. RESULT: Optimum fermentation conditions were modeled to be an inoculum of 5.40% (v/v), a liquid-solid ratio of 27.45 mL g-1 and a rotation speed of 184 rpm and were predicted to yield 292.99 g kg-1 TB. Under these experimentally conditions, the TB content of the instant dark tea was 291.93 g kg-1 . The antioxidant capacity and α-glucosidase and pancreatic lipase inhibitory activities of the high-TB instant black tea were higher than four other typical instant dark tea products. CONCLUSION: The results of the present study show that careful management of culture conditions can produce a dark tea high in theabrownins. Furthermore, high-theabrownins instant dark tea could serve as a source of bioactive products and be used in functional foods as an ingredient imparting antioxidant properties and the ability to inhibit pancreatic lipase and α-glucosidase.
BACKGROUND: Theabrownins (TB) are bioactive components that are usually extracted from Chinese dark tea, in which they are present at low concentrations. The present study aimed to produce an instant dark tea high in theabrownins via submerged fermentation by the fungus Aspergillus niger. Three fermentation parameters that affect theabrownins content (i.e. inoculum size, liquid-solid ratio and rotation speed) were optimized using response surface methodology. RESULT: Optimum fermentation conditions were modeled to be an inoculum of 5.40% (v/v), a liquid-solid ratio of 27.45 mL g-1 and a rotation speed of 184 rpm and were predicted to yield 292.99 g kg-1 TB. Under these experimentally conditions, the TB content of the instant dark tea was 291.93 g kg-1 . The antioxidant capacity and α-glucosidase and pancreatic lipase inhibitory activities of the high-TB instant black tea were higher than four other typical instant dark tea products. CONCLUSION: The results of the present study show that careful management of culture conditions can produce a dark tea high in theabrownins. Furthermore, high-theabrownins instant dark tea could serve as a source of bioactive products and be used in functional foods as an ingredient imparting antioxidant properties and the ability to inhibit pancreatic lipase and α-glucosidase.