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Aspergillus amstelodami A1 isolated from Pu-erh tea was inoculated in sterilized or unsterilized sun-dried green tea leaves to develop pure culture fermentation and enhanced fermentation (EF) of Pu-erh tea. The results showed that the content of tea polyphenols and five catechins in tea decreased significantly, and the content of thearubigins and theabrownins increased significantly after pure culture fermentation. Compared with natural fermentation, the levels of soluble sugars and theabrownins in EF were significantly higher, whereas the levels of gallic acid, (+)-catechin, (-)-epicatechin, (-)-epigallocatechin and caffeine were significantly lower; the scores of sensory evaluation including appearance, color of infusion, taste, aroma and infused leaves in EF were significantly higher; while the value of a* and b* of EF's tea infusion were higher and the value of L* was lower. A. amstelodami A1 didn't become the dominant fungi in EF, while the microbial communities in EF were different from those in NF. Therefore, the enhanced fermentation by inoculation of A. amstelodami A1 changed the chemical components of tea leaves through the synergistic effect with other microorganisms, therefore improving the sensory quality of Pu-erh tea. [ABSTRACT FROM AUTHOR]

Wuliangye‐flavor liquor (WLFL), a specific Chinese traditional liquor, one of the major type of global distilled spirits, offers a unique flavor system acquired across thousands of years of development. Free amino acids (FAAs), as major health factors, are considered to be primarily derive from the hydrolysis of protein from the Zaopeis (ZPs) by microbial populations during fermentation. Here, we investigated the changes of microbial communities in ZPs and FAAs in raw liquor (RL) directly related ZPs from different ages of WLFL fermentation pits by phospholipid fatty acid fingerprint (PLFA) and high performance liquid chromatography method. Results indicated that the total PLFAs of 20‐ and 50‐year ZPs were significantly higher (p <.05) than 1‐ and 5‐year ZPs. Gram‐positive bacteria (G+), anaerobic bacteria, and fungi were dominant in the ZPs. Furthermore, the total of FAAs content was highly increased (p <.05) in RLs of aged fermentation pit (20‐ and 50‐year, 24.86–30.23 mg/g, 28.73–37.15 mg/g) compared with young (1‐ and 5‐year, 20.97–26.46 mg/g, 17.83–28.70 mg/g), while, the different ages of RLs could be distinguished according to 9 biomarkers of FAAs (Variable importance in projection, VIP >1; p <.05), including tyrosine, aspartic acid, leucine, glutamic acid, citrulline, alanine, proline, glycine, and valine. Particularly, the biomarkers of FAAs were positively correlated with gram‐negative bacteria (G−) and fungi, but negatively correlated with G+. This is the first report to uncover the microbial communities in zaopeis, free amino acids in RL, and their correlations for Wuliangye‐flavor raw liquor production. [ABSTRACT FROM AUTHOR]

• Wuliangye-flavor liquor uses various grades of raw liquors with specific proportions. • 75 aroma components were identified by HS-SPME/LLME-GC–MS. • 13 differential aroma components were negatively correlated with G+ and aerobe. • Improving the utilization rate of raw liquors with medium and low quality. As the main raw material for commercial Wuliangye-flavor liquor, Wuliangye-flavor raw liquor (WFRL) plays an important role in the formation of flavor components. Aroma components and microbial community diversity of 4 WFRLs produced by the same fermenting cellar were investigated by headspace solid phase microextraction, liquid-liquid microextraction combined gas chromatography-mass spectrometry and phospholipid fatty acid fingerprint method. Correlations between aroma components and microbial community of WFRL were disclosed by multivariate statistical analysis techniques. Results indicated that a total of 75 aroma components were identified, including 39 esters, 11 alcohols, 9 acids, 7 aldehyde, 5 ketones and 4 others, whereas esters were dominant for the samples (67.49%). Meanwhile, Gram-positive bacteria (G+) and aerobe in the fermenting cellar increased gradually from top to bottom, compared with Gram-negative bacteria (G−), anaerobe and fungi showed the opposite trend. Furthermore, 4 WFRLs could be distinguished according to 13 differential aroma components (VIP > 1, P < 0.05). Whereas, the differential aroma components were positively correlated with G−, anaerobe and fungi, but negatively correlated with G+ and aerobe. In particular, 4 key esters including ethyl caproate, ethyl acetate, ethyl butyrate and ethyl lactate that determine the grade of WFRL were positively correlated with anaerobe and fungi. Therefore, the results can be used as a reference to understand the correlation between aroma components and microbial communities in different quality grades of WFRL. [ABSTRACT FROM AUTHOR]