Eurotium amstelodami with bacterial assistance generated jinhua fungus aroma and enhanced hypoglycemic effect during compressed tea storage

Jinhua formation during storage (JFDS) is associated with golden-flower fungus and its microbial interaction, which can be used to investigate microbial effect during compressed tea storage. Contrastive analysis between jinhua raw Pu-erh tea (JRAPT) and its identical raw Pu-erh tea (RAPT) confirmed Eurotium amstelodami as dominant golden-flower fungus with a relative abundance over 98.0 % for the JFDS. Along with the JFDS, E . amstelodami showed positive correlation ( P < 0.05 and r > 0.80) with Ralstonia , Turicibacter , Methyloversatilis and Aquabacterium. With relevant bacterial assistance, E. amstelodami was responsible for characteristic flavor formation such as jinhua fungus aroma, and in vitro hypoglycemic effect improvement during tea storage. Concretely, E . amstelodami -mediated JFDS accelerated tea aging, and bitterness-astringency taste and in vitro antioxidant capacity reductions through hydrolysis, oxidative polymerization and condensation of catechins, rutin, 1,3,6-tri- O -galloyl- β -D-glucose and free amino acids to accumulate theabrownins, flavonols and phenolic acids. Additionally , β -linalool, trans - β -ionone, α -cedrene and (-)- α -santalene with floral, woody or herbal odor were derived from farnesyl diphosphate and β -carotene degradation, and linalool glycoside hydrolysis pathways to generate jinhua fungus aroma. This study would provide theoretical foundation for exogenous inoculation of E . amstelodami and other functional microbes in tea storage. • Eurotium amstelodami was golden-flower fungus for jinhua formation during storage (JFDS). • JFDS accelerated tea aging, bitterness-astringency and antioxidant ability decreases. • β -Linalool, trans - β -ionone, α -cedrene, (-)- α -santalene increases generated jinhua fungus aroma. • E. amstelodami dominated flavor formation and hypoglycemic effect improvement in JFDS. • Ralstonia , Turicibacter , Methyloversatilis and Aquabacterium were functional bacteria.