Search

In this study, six lipase-producing strains from food sources were screened for their ability to produce lipase. Among them, Staphylococcus epidermidis N30 and Yarrowia lipolytica C11 demonstrated high enzyme activities of 1.07 and 0.84 U/mL, respectively. They had the following enzymatic properties: optimum reaction temperature of 50 ℃ and pH of 8.0. The optimum substrate for S. epidermidis N30 was C4 ester, while that for Y. lipolytica C11 was C8 ester. The inoculation of sour meat with S. epidermidis N30 or Y. lipolytica C11 effectively enhanced the production of flavor substances, especially ethyl butyrate, ethyl caproate, ethyl caprylate, ethyl caprate, nonanal and 1-octen-3-ol, thus promoting the production of fruity, floral, wine-like, mushroom-like and fatty aromas in sour meat.

To examine the variances in volatile organic compounds (VOCs) and sensory attributes across various hop cultivars, an analytical approach was employed. Specifically, gas chromatography-ion mobility spectroscopy (GC-IMS), gas chromatography-mass spectrometry (GC-MS), and quantitative descriptive analysis (QDA) were employed to scrutinize the VOCs and sensory characteristics of four distinct hop varieties, namely Magnum, Palisade, Saaz, and Hersbrucker. The outcomes of QDA revealed a diverse array of sensory profiles in the hops, encompassing citrus and non-citrus fruit aromas, woody, floral, herbal, spicy, and green aromas, with noticeable distinctions in sensory attributes discernible among the various hop cultivars. The results showed that 79 VOCs were identified in the GC-IMS spectra of different varieties of hops, including terpenes, alcohols, esters, aldehydes, and ketones. 140 VOCs were identified in the GC-MS spectra of different varieties of hops, including terpenes, alcohols, ketones, esters, acids, and aldehydes, with terpenes and esters emerging as the prevailing constituents in hops. The principal component analysis (PCA) of different hop VOCs was performed to effectively identify the differences among hop varieties. This study can provide a valuable reference for the comprehensive analysis of VOCs and sensory attributes in hops. Furthermore, it contributes theoretical underpinnings to inform the precise application of hops in the context of beer brewing. [ABSTRACT FROM AUTHOR]

Strong-flavor Daqu, as a fermentation agent, plays a significant role in shaping the quality of strong-flavor baijius, and fungal species in Daqu are important factors affecting the quality of Daqu. Therefore, we selected strong-flavor Daqu from seven different origins to study the fungal composition and the effects of the fungal composition on the physicochemical properties and volatile organic compounds (VOCs). It was found that the fungal composition influences the physicochemical properties of Daqu. Specifically, there was a positive link between Rhizomucor, Rhizopus, Thermomyces, and liquefying activity and a positive correlation between Aspergillus and fermenting activity. Furthermore, the relationships between esterifying activity and Thermomyces, Rhizomucor, Aspergillus, Pichia, and Saccharomycopsis were found to be positive. The VOCs in Daqu were affected by Aspergillus, Issatchenkia, Pichia, and Thermoascus. Issatchenkia was significantly positively correlated with benzeneethanol as well as Aspergillus and pentadecanoic acid ethyl ester, ethyl myristate. Pichia and Thermoascus were significantly negatively correlated with benzaldehyde and 2-furaldehyde. This study deepens our understanding of the relationship between VOCs, the physicochemical properties with microbial communities, and reference significance for the production of better-quality strong-flavor Daqu. [ABSTRACT FROM AUTHOR]

Summary: The present study evaluated the relationship between the bacterial diversity and metabolites of various sour meats, a traditional fermented meat product. The results showed that sour meats had a low pH (average of 4.34), low water activity (aw, an average of 0.917), and high lactic acid (~19 177.48 mg kg−1) and free amino acid (FAA) (~4047.65 mg kg−1) concentrations. The lactic acid bacteria (LAB), especially Lactobacillus and Weissella, were predominated in the samples. The alcohols, aldehydes and esters accounted for the major components of volatile organic compounds (VOCs). Of which, (E)‐2‐octenal, nerol, cis‐4‐decenal, tetradecanal, linalyl acetate, linalool, 1‐octen‐3‐ol, hexanal, 1‐heptanol, benzaldehyde and (E)‐2‐decenal were considered as the key VOCs of sour meats. The redundancy analysis (RDA) and Pearson's correlation analysis revealed that LAB (Lactobacillus and Weissella) and salt were positively correlated with most FAAs and VOCs. Overall, higher salinity, lower aw and abundant LAB might be the indicators of good sour meat quality. [ABSTRACT FROM AUTHOR]

Pyrazines are important flavor components and healthy active components in Baijiu, which including tetramethylpyrazine (TTMP). During the brewing process, the traceability of microbial communities and the content distribution characteristics of TTMP are important for improving the quality and style characteristics of compound-flavored Baijiu (CFB). However, the traceability analysis of microorganisms in fermented grains (FG)-used in the production of CFB-lacks quantitative and systematic evaluation. In this study, the microbial communities and TTMP content of Jiuqu (JQ), Liangpei (LP), FG, and pit mud (CP) used in CFB production were characterized; further, coordinate and discriminant analyses were employed to determine differences in microbial communities. Additionally, traceability and correlation analyses were performed to reveal the origin of microbial communities in FG. The source, content, and distribution characteristics of TTMP based on the brewing process have also been discussed. The results showed that most of the bacterial and fungal communities at different levels of FG came from other sources, and the microorganisms of Cladosporium, Acetobacter, Aspergillus, Methanosarcina , and Bacillus were considered have a osculating correlations with TTMP content of FG. Taken together, this study provides insights into the origin of microbial communities in FG and the distribution characteristics of TTMP based on the CFB brewing process. The current findings are conducive for optimizing the fermentation process and improving the quality and style characteristics of CFB., Competing Interests: WC, XX, TP, NL, and HY were employed Anhui Jinzhongzi Distillery Co., Ltd. HL was employed China Resources Snow Breweries Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Cheng, Lan, Chen, Xue, Liang, Zeng, Li, Pan, Li and Yang.)