Luminescence and fahua-fermentation qualities of an autofluorescent microorganism from Fu brick tea

Recently, the autofluorescence of Fu brick tea was observed during its production and consumption. Notably, the autofluorescence intensity of Fu brick tea varies in different locations. To explore underlying cause of autofluorescence, we detected ten types of microorganisms from Jingwei Fu tea and Xiangyi Fu tea, which contain the same raw materials but undergo different processing environments, leading to different autofluorescence levels. Consequently, we found that Eurotium cristatum and Aspergillus chevalieri are responsible for the autofluorescence of Fu tea. The differences in autofluorescence intensity are due to different densities of the two fungal species. And the fluorescence intensity of these fungi was affected by pH, temperature, and staining concentration. Therefore, different processing environments lead to different autofluorescence intensities of Fu tea. Additionally, we inoculated the two strains into raw dark tea, we observed altered contents of amino acids, catechins, etc.in dark tea, and these changes correlated with the autofluorescence intensity. Novelty impact statement The cause of autofluorescence of Fu brick tea was obtained. We observed E. cristatum and A. chevalieri produced autofluorescence in these teas. Microorganisms caused changes in various biochemical components of the teas.