Thermal generation of 3-amino-4,5-dimethylfuran-2(5H)-one, the postulated precursor of sotolone, from amino acid model systems containing glyoxylic and pyruvic acids

Revealing the comprehensive effect of mechanization on sauce-flavor Daqu through high-throughput sequencing and multi-dimensional metabolite profiling

Mechanization has emerged as a focal point in the modernization of traditional enterprises, offering standardized production and labor reduction benefits. However, little is known about how mechanization affects the microbiota and metabolite profiles of Daqu. To address this gap, we conducted a comprehensive comparison between traditional and mechanical sauce-flavor Daqu using a multi-omics approach. Results showed that mechanical Daqu exhibited higher acidity, amino acid nitrogen and enzyme activity, alongside lower fat and moisture levels. Following mechanization, lactic acid bacteria (LAB), Staphylococcus, Aspergillus and Saccharomycopsis were enriched and identified as biomarkers, whereas Oceanobacillus, Monascus and Scopulariopsis were notably decreased. Furthermore, significant disparities in metabolic profiles were observed between the two types of Daqu based on GC-MS, GC-IMS, and LC-MS/MS analyses. The content of volatile compounds was significantly higher in mechanical Daqu (332.82 ± 22.69 mg/kg), while that of non-volatile compounds was higher in traditional Daqu (753.44 ± 41.82 mg/kg). Moreover, OPLS-DA models identified 44 volatile and 31 non-volatile compounds as differential metabolites. Multivariate statistical analysis indicated that bacteria and fungi primarily contributed to protease and saccharification activities, respectively. Additionally, the co-occurrence network revealed that Oceanobacillus and Scopulariopsis were closely associated with non-volatile compound formation, while LAB and Rhizopus significantly influenced volatile compound production. These findings elucidate the multi-dimensional relationship between mechanization and Daqu quality, offering insights to advance the modernization of traditional industries.

Characterization of Key Aging Aroma Compounds in Aged Jiangxiangxing Baijiu and Their Formation Influencing Factors during the Storge Process

Long-term storage Baijiu has an appealing sensory property, yet the chemical makeup is rarely reported. This study investigated a 30-year-old Jiangxiangxing (JXX) Baijiu and recognized and measured 69 aroma compounds. 3-Methyl-2,4-nonanedione (2.76 μg/L), 2,5-dimethyl-4-hydroxy-3(2H)-furanone (HDMF, 46.2 μg/L), 2-ethyl-4-hydroxy-5-methyl-3(2H)-furanone (HEMF, 61.7 μg/L), and piperitone (3.66 μg/L) were detected for the first time in Baijiu. Compared with 3-year-old JXX Baijiu, 24 compounds were significantly higher in the 30-year-old, mainly including furans, pyrazines, and aromatics. Notably, 4,5-dimethyl-3-hydroxy-2(5H)-furanone (sotolon), HDMF, HEMF, vanillin, acetovanillone, and alkyl pyrazines in 30-year-old JXX Baijiu were 2-7 times higher than those of a 3-year-old, and they increased steadily during aging for 3, 15, and 30 years, assumed to be associated with the aging aroma. Following 24 months of storing JXX Baijiu under different conditions, the pottery significantly promoted the synthesis of sotolon, HDMF, HEMF, and alkyl pyrazines. These findings suggest that pottery is a potential catalyst for enhancing aged Baijiu.

A systematic review on the flavor of soy-based fermented foods: Core fermentation microbiome, multisensory flavor substances, key enzymes, and metabolic pathways

The characteristic flavor of fermented foods has an important impact on the purchasing decisions of consumers, and its production mechanisms are a concern for scientists worldwide. The perception of food flavor is a complex process involving olfaction, taste, vision, and oral touch, with various senses contributing to specific properties of the flavor. Soy-based fermented products are popular because of their unique flavors, especially in Asian countries, where they occupy an important place in the dietary structure. Microorganisms, known as the souls of fermented foods, can influence the sensory properties of soy-based fermented foods through various metabolic pathways, and are closely related to the formation of multisensory properties. Therefore, this review systematically summarizes the core microbiome and its interactions that play an active role in representative soy-based fermented foods, such as fermented soymilk, soy sauce, soybean paste, sufu, and douchi. The mechanism of action of the core microbial community on multisensory flavor quality is revealed here. Revealing the fermentation core microbiome and related enzymes provides important guidance for the development of flavor-enhancement strategies and related genetically engineered bacteria.

Oxygen-induced faults in bottled white wine: A review of technological and chemical characteristics

Several changes can take place in wine after blotting. Some of them lead to the desired evolution of wine being more complex, round and pleasant. However, unexpected changes can also occur ascribable to the premature wine oxidation (PremOx) arising when a wine, presumably with aging potential, results oxidized and often undrinkable. The complexity of PremOx, where aromas are also involved, makes difficult to identify all the oxidation products, and to predict its occurrence in wines. Despite most studies have been focused on the effect of time after wine bottling on PremOx as well as pinking phenomena, identification of pinking markers, reliable methods for their detection in wine, and correlations between markers and the wine-bottle-closure system are still unknown. This review aimed to highlight aspects PremOx-related, including wine-bottle-closure system, color change, with particular emphasis on pinking, and aroma decay based on the current knowledge becoming the bases for future perspectives.

Rapid Determination of Sotolon in Fortified Wines Using a Miniaturized Liquid-Liquid Extraction Followed by LC-MS/MS Analysis

Sotolon (4,5-dimethyl-3-hydroxy-2,5-dihydrofuran-2-one) is a powerful odorant usually pointed out as being responsible not only for the characteristic curry notes of the finest fortified wines but also for the off-flavour notes in prematurely oxidized white wines. Most methods reported in literature for quantifying sotolon in wines are quite laborious and use large volumes of organic solvents. Thus, in the present study, the development of a simple, fast, and environment-friendly method for the quantification of sotolon in fortified wine is herein presented. The proposed method uses a single-step liquid-liquid extraction followed by RP-LC-MS/MS and was optimized using a full factorial design. The method showed good linearity (R ² = 0.9999), intra- and interday precision lower than 10% RSD, recovery of about 95%, and high sensitivity (LOQ of 0.04 μg/L). The method was applied to analyse 44 fortified wines from different styles (from dry to sweet wines) and ages (3-115 years old), and it was found that it covers the concentration range usually found for this compound in this kind of alcoholic beverages, which was found to be within 6.3-810 μg/L. Thus, it can be concluded that this method can be used as an accurate tool for the rapid analysis of sotolon, since the early stages of its formation up to long ageing periods.