Identification of “Golden Flower” Fungi and Quality Changes of Fermented Liupao Tea Inoculated with Them

Abstract

Four “Golden Flower” fungi were isolated from the pile-fermentation process of Liupao tea, and named LB-22, LB-32, LB-35 and LB-55, respectively. Based on colony morphological characteristics, optical microscopic structural characteristics, internal transcribed spacer (ITS) sequence alignment and analysis and phylogenetic analysis, the four strains were identified as Penicillium manginii, Aspergillus ruber, A. intermedius and A. amstelodami. The four “Golden Flower” fungi were separately inoculated into sterilized raw Liupao tea from the Cangwu variety group for solid-state fermentation. The effects of these fungi on the sensory quality and major physicochemical properties of fermented Liupao tea were investigated through sensory evaluation, biochemical component detection and principal component analysis (PCA). The results showed that the taste of Liupao tea changed from heavy and strong to mellow and thick after fermentation by “Golden Flower” fungi, the aroma changed from coarse-fired to stale, woody and arohid, and the color of tea infusion changed from bright yellow-green to bright, intense red. PCA and hierarchical cluster analysis (HCA) showed clear distinction between “Golden Flower” fungi fermented tea and the unfermented control. Compared with the control group, the contents of flavonoids, total free amino acids, tea polyphenols, thearubigin, catechin (EC, CG, C, EGCG, GCG and ECG) and total catechin significantly decreased in the fermented groups (P < 0.01), whereas the contents of theabrownins significantly increased (P < 0.01). This study provides a reference for the application of “Golden Flower” fungi in Liupao tea, and offers a theoretical basis for research on the industrialization and product development of “Golden Flower” fungi fermented Liupao tea.

Keywords

• liupao tea; “golden flower” fungi; solid-state fermentation; principal component analysis