Effects of Eurotium cristatum on chemical constituents and α-glucosidase activity of mulberry leaf tea

To expand the range of mulberry leaf tea products, the present study used ‘Shaansang 707’, ‘Yuesang 10’ and ‘Husang 32’ as raw materials to prepare mulberry leaf Fu loose tea by solid-state fermentation, with artificial inoculation of Eurotium cristatum. The nutrients and active components of mulberry leaf tea before and after fermentation were determined. Compared with mulberry leaf raw dark green tea, the contents of tea pigments in Fu tea, especially theabrownin were greatly increased by more than 11%, while those of polyphenols, flavonoids and polysaccharides were significantly decreased (p < 0.05). In addition, mulberry leaf Fu tea exhibited better α-glucosidase inhibitory activity than mulberry leaf raw dark green tea. Multivariate analysis suggested that the enhancement of α-glucosidase inhibitory ability was most likely related to theabrownin. The results of this study will provide a theoretical basis for the industrial production of mulberry leaf Fu tea.