In this study, characterises of the microbial community structures of three typical Chinese liquor Daqu, as well as different kinds of light flavour Daqu were investigated using nested PCR-denaturing gradient gel electrophoresis (DGGE). The results showed that microbial diversity was considerably different, and the microfloral compositions were highly variable among various Daqu. Lactic acid bacteria, which accounted for 30.95 % of all identified bacteria, were dominant in all Daqu samples, whereas Bacillus species were also predominant in the Luzhou (14.8 %) and Langjiu Daqu (18.2 %). Citrobacter and Burkholderia were first identified in light flavour Daqu. Aspergillus was the dominant moulds, and the non-Saccharomyces yeast species, Saccharomycopsis fibuligera, Wallemia sebi, Wallemia muriae, and Pichia subpelliculosa, were the dominant yeasts. Rasamsonia, Galactomyces, Geotrichum and Wallemia were first identified using nested PCR-DGGE. Cluster analysis indicated that the microbial community structures of different Daqu samples exhibited some differences. These may be ascribed to the different peak production temperatures, raw material constituents and microhabitats around the liquor enterprises. The current study provides insights into the microbial community structures of three typical Daqu samples, and may facilitate the development of starter cultures for manufacturing Chinese liquor.

It is vital to understand the changing characteristics of interphase microbial communities and interspecies synergism during the fermentation of Chinese liquors. In this study, microbial communities in the three indispensable phases (pit mud, zaopei, and huangshui) of Luzhou-flavored liquor manufacturing pits and their shifts during cellars use were first investigated by polyphasic culture-independent approaches. The archaeal and eubacterial communities in the three phases were quantitatively assessed by combined phospholipid ether lipids/phospholipid fatty acid analysis and fluorescence in situ hybridization. In addition, qualitative information regarding the microbial community was analyzed by PCR-denaturing gradient gel electrophoresis. Results suggested that the interphase microbial community profiles were quite different, and the proportions of specific microbial groups evolved gradually. Anaerobic bacteria and gram-positive bacteria were dominant and their numbers were higher in pit mud (10 cells/g) than in huangshui (10 cells/ml) and zaopei (10cells/g). Hydrogenotrophic methanogenic archaea were the dominant archaea, and their proportions were virtually unchanged in pit mud (around 65%), whereas they first increased and then decreased in zaopei (59%-82%-47%) and increased with pit age in huangshui (82%-92%). Interactions between microbial communities, especially between eubacteria and methanogens, played a key role in the formation of favorable niches for liquor fermentation. Furthermore, daqu (an essential saccharifying and fermentative agent) and metabolic regulation parameters greatly affected the microbial community.

APM cultivation technology was necessary to promote enriching functional liquor-brewing microbes into APMs. These results may facilitate understanding the microbial succession during APMs manufacture.

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Present study was to characterize the physiochemical properties, free amino acids (FAAs), volatiles and microbial communities of various moromi, respectively sampled from different stages of high-salt dilute-state (HSDS) and low-salt solid-state (LSSS) fermentation, using multiphase analyzing methods. Phospholipid fatty acids (PLFA) analysis indicated that Gram-positive bacteria were dominant bacteria and fungi were principal microbes. For DGGE analysis, dominant microbes in moromi were mainly fell into Weissella, Tetragenococcus, Candida, Pichia, and Zygosaccharomyces. During fermentation, the dominant microbes shifted from nonhalophilic and less acid-tolerant species to halophilic and acid-tolerant species. Total of 15 FAAs and 44 volatiles were identified in moromi, mainly Glu, Asp, Tyr, and acids, alcohols, esters, aldehydes, respectively. Odor activity values analysis suggested that the final moromi of LSSS fermentation had more complicated odors than that of HSDS fermentation. Conclusively, technological parameters, microbial communities, raw materials and fermentation process may result in the discrepancy of HSDS and LSSS moromi.

Trimethylamine (TMA) is one of the important chemical indexes to judge the freshness of marine fish. It is necessary to develop a low temperature TMA sensor to help the monitoring and prediction of the quality of marine fish in cold chain. Herein, a flexible low temperature TMA gas sensor featuring antifreezing and superior mechanical properties was developed based on the Au nanoparticle-modified MXene (MXene@Au) composite. MXene@Au was synthesized and then polymerized with a hydrogel composed of acrylamide (AM), N,N′-methylenebisacrylamide (BIS), sodium carboxymethyl cellulose (CMC), and EG, and the resultant MXene@Au hydrogel was found to exhibit excellent antifreezing performance even at extremely low temperature as well as high tensile strength, ultrastretchability, and toughness, which enabled an efficient gas sensing platform for TMA detection at low temperature. The TMA sensing properties of the flexible MXene@Au DN hydrogel sensor at 25 °C and a low temperature of 0 °C were studied, and a linear relationship between TMA sensitivity and concentration was built. The excellent sensing properties were maintained even under deformation. The application of the MXene@Au DN hydrogel sensor in detection of fish freshness at 0 °C was investigated. The result indicated the potential application of the flexible MXene@Au DN hydrogel gas sensor in dynamic quality monitoring and prediction of marine fish products during its transportation and storage in the cold chain.

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