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Research on identification, function and safety of Aspergillus Niger, a preponderant fungus during the fermentative process of Pu'er tea

Objective To understand the function and safety of Aspergillus niger during the fermentative process of Pu'er tea. Methods The preponderant fungus S6 was separated and purified from Pu'er tea in the plate method, and it was Aspergillus niger through the use of molecular identification. Then Aspergillus niger, following suspension 107/m L, was inoculated on the sun-dried green tea with 35% water, cultured for 25 d with 30 ℃, then the sensory, security, physical and chemical evaluations of fermented sample were operated according to GB 22111-2008. Results The research results showed that compared with CK, the content of the tea sample in fermentation of Aspergillus niger was the abrownins, redness and brightness. It was achieved the third standard and was changed significantly in the fermented sample with sweet aroma, black brown tang, velvety flavor, and the content of ochratoxin was 3.80 μg/kg under the limitation of home and abroad. Conclusion Aspergillus niger is one of preponderant fungus during the fermentative process of Pu'er tea, and plays a very important role to the formation of Pu'er tea quality with high safety.