High-theabrownins instant dark tea product by Aspergillus niger via submerged fermentation: alpha-glucosidase and pancreatic lipase inhibition and antioxidant activity.
Wang YW, Zhang MY, Zhang ZZ, Lu HQ, Gao XL*, Yue PX*
J Sci Food Agric. 2017 Apr 19. doi: 10.1002/jsfa.8387.
Theabrownins (TB) are bioactive components usually extracted from Chinese dark tea, where they are present in low concentrations. This 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, namely inoculum size, liquid-solid ratio and rotation speed, were optimized using response surface methodology.
Optimum fermentation conditions were modeled to be an inoculum of 5.40 % (v/v), a liquid-solid ratio of 27.45 mL/g and a rotation speed of 184 r/min and were predicted to yield 292.99 g/kg TB. Under these conditions, the TB content of the instant dark tea was experimentally produced at 291.93 g/kg. 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.
Our findings show that careful management of culture conditions can produce a dark tea high in theabrownins. The results further suggested that high-theabrownins instant dark tea could serve as a source of bioactive products for use in functional foods as an ingredient imparting antioxidant properties and the ability to inhibit the enzymes pancreatic lipase and α-glucosidase.