To investigate the changes of phenolic metabolite during different grains fermentation stages of Chinse Baijiu, the ultra-performance liquid chromatography-quadrupole time of-flight mass spectrometry (UHPLC-QTOF-MS) was applied to identify and analyze the different phenolic metabolites, combined with principal component analysis and partial least squares discriminant analysis. Results indicated that significant differences in phenolic metabolites during different fermentation stages were found. Among the 231 phenolic metabolites detected, 36, 31, 19, 23, 14, and 50 differential phenolic metabolites were screened between different groups using partial least squares discriminant analysis. Twelve metabolic pathways with high correlation of differential phenolic metabolites and 23 main participating differential metabolites were identified through KEGG metabolic pathway enrichment analysis. The present study preliminarily revealed the differences of phenolic metabolites at different fermentation stages, and providing a theoretical basis for the further improving of the taste and quality of Chinese Baijiu.

The fermentation process of Chinese Baijiu\'s fermented grains involves the intricate succession and metabolism of microbial communities, collectively shaping the Baijiu\'s quality. Understanding the composition and succession of these living microbial communities within fermented grains is crucial for comprehending fermentation and flavor formation mechanisms. However, conducting high-throughput analysis of living microbial communities within the complex microbial system of fermented grains poses significant challenges. Thus, this study addressed this challenge by devising a high-throughput analysis framework using light-flavor Baijiu as a model. This framework combined propidium monoazide (PMA) pretreatment technology with amplicon sequencing techniques. Optimal PMA treatment parameters, including a concentration of 50 μM and incubation in darkness for 5 min followed by an exposure incubation period of 5 min, were identified. Utilizing this protocol, viable microorganism biomass ranging from 8.71 × 106 to 1.47 × 108 copies/μL was successfully detected in fermented grain samples. Subsequent amplicon sequencing analysis revealed distinct microbial community structures between untreated and PMA-treated groups, with notable differences in relative abundance compositions, particularly in dominant species such as Lactobacillus, Bacillus, Pediococcus, Saccharomycopsis, Issatchenkia and Pichia, as identified by LEfSe analysis. The results of this study confirmed the efficacy of PMA-amplicon sequencing technology for analyzing living microbial communities in fermented grains and furnished a methodological framework for investigating living microbial communities in diverse traditional fermented foods. This technical framework holds considerable significance for advancing our understanding of the fermentation mechanisms intrinsic to traditional fermented foods.

Molecular mechanisms underlying the aging of Chinese Baijiu remained elusive. This study proposed the self-assembly behavior of amphiphilic molecules dominated by hydrogen bonds in Chinese Baijiu for the first time. The self-assembly degree of amphiphilic clusters gradually intensifies with the prolonged storage time of Baijiu, comprehensively characterized at both micro and macro levels. The results indicated that the blue-shift of the Raman hydrogen bond vibrational peak (about 11 cm-1 and 7 cm-1, respectively), the increase in viscosity (5.71% and 2.22%, respectively), and the rise in dielectric constant (95.63% and 94.99%, respectively) during the 17-year cellaring process of Strong-flavor Baijiu and Jiang-flavor Baijiu were consistent with the evolutionary trends observed in molecular dynamics simulations. The essential driving factors of cluster structure alteration of amphiphilic aroma substances in Chinese Baijiu during cellaring were demonstrated from molecular level. This study provided a research approach to comprehending the aging mechanism of Chinese Baijiu from the micro level.

Chinese Baijiu (Liquor) is a popular alcoholic beverage, and the ethanol content in Baijiu is closely related to its quality; therefore, it is of great significance to explore a facile, sensitive, and rapid method to detect ethanol content in Baijiu. Hydrophobic carbon quantum dots (H-CQDs) with bright red fluorescence (24.14 %) were fabricated by hydrothermal method using o-phenylenediamine, p-aminobenzoic acid, manganese chloride, and hydrochloric acid as reaction precursors. After the introduction of ultrapure water into the ethanol solution dissolved with H-CQDs, the aggregated H-CQDs resulted in significant changes in fluorescence intensity and absorbance. On this basis, a sensor for detecting ethanol by optical dual-mode and smartphone imaging was constructed. More importantly, the sensor can be used for detecting ethanol content in Chinese Baijiu with satisfactory results. This sensing platform has great potential for quality identification in Chinese Baijiu, broadening the application scope of CQDs in food safety detection.

In this study, the novel polysaccharides named HSP-0 M and HSP-0.1 M were successfully purified from Huangshui (HS), and their structural properties and bioactivities were investigated. Structural analysis revealed that HSP-0 M had a molecular weight of 493.87 kDa and was composed of arabinose, galactose, glucose, xylose, and mannose in a molar ratio of 1.48:1.09:26.52:1.33:1.00. On the other hand, HSP-0.1 M was made up of fructose, arabinose, galactose, glucose, xylose, mannose, ribose, galacturonic acid and glucuronic acid in a ratio of 2.67:26.00:29.10:36.83:16.22:30.53:1.00:1.43:3.64 with a molecular weight of 157.6 kDa. Methylated and 2D NMR analyses indicated that T-Glcp-(1 → 4)-Glcp-(1 → 2)-Glcp-(1 → 3)-Glcp was the primary chain of HSP-0 M, and the backbone of HSP-0.1 M was made up of →3)-Galp-(1 → 6)-Manp-(1 → 3)-Glcp-(1 → 6)-Glcp-(1 → 2)-Manp-(1 → 6)-Glcp-(1 → 3)-Galp. Morphological research showed that both polysaccharides were homogeneous as well as exhibit a web-like structure and an irregular lamellar structure. Furthermore, HSP-0 M demonstrated the capacity to safeguard Lactococcus lactis from damage caused by low temperatures and freeze-drying, while HSP-0.1 M exhibited noteworthy antioxidant activity. These results established a theoretical foundation for the applications of HSPs in food products, cosmetics, and medicines.

Ethyl carbamate (EC), a 2A carcinogen produced during the fermentation of foods and beverages, primarily occurs in distilled spirits. Currently, most studies focus on strategies for EC mitigation. In the present research, we aimed to screen strains that can degrade EC directly. Here, we report two Candida ethanolica strains (J1 and J116), isolated from fermented grains, which can reduce EC concentrations directly. These two yeasts were grown using EC as the sole carbon source, and they grew well on different carbon sources. Notably, after immobilization with chitosan, the two strains degraded EC in Chinese Baijiu by 42.27% and 27.91% in 24 h (from 253.03 ± 9.89 to 146.07 ± 1.67 and 182.42 ± 5.05 μg/L, respectively), which was better than the performance of the non-immobilized strains. Furthermore, the volatile organic compound content, investigated using gas chromatography-mass spectrometry, did not affect the main flavor substances in Chinese Baijiu. Thus, the yeasts J1 and J116 may be potentially used for the treatment and commercialization of Chinese Baijiu.

Baijiu is a traditional spirit with high reputation in the Chinese community, and whisky, on the other hand, is a renowned spirit in Western culture, with both contributing a major proportion to the consumption and revenue in the global spirit market. Interestingly, starting with similar raw materials, such as grains, diverse production methods lead to different organoleptic profiles. In addition, such enormous attention they attract renders them as a crucial part in food and the related industry. Therefore, great efforts are made in improving product quality and optimizing production processes, such as flavor enhancement, facility development, and deep utilization of byproducts. Given the huge impacts and great involvements of these spirits in the general food industry, research focusing on either spirit is of referential significance for other relevant fields. With the aim of facilitating such collaboration, this review discusses the current research status, in a comparative manner, of both spirits in respect to key production processes-oriented sensory and flavor analysis, deep utilization of byproducts, and spirit-derived functional food investigations. Finally, the internal correlations based on the abovementioned criteria are identified, with research prospects proposed.

Commercial koji has been increasingly used in Chinese Baijiu brewing; however, there are only few studies comparing different koji and their relationship with key components of Chinese Baijiu such as ethyl acetate, ethyl lactate, and higher alcohols. Here, we studied six commercially available koji and showed that the microbial communities in the individual koji varied in composition, with Rhizopus, Aspergillus, and Bacillus primarily associated with starch hydrolysis and Saccharomyces mainly associated with alcohol production. In the brewing processes using the six koji, Saccharomyces was undoubtedly the most abundant fungus and Weissella, Bacillus, and Acinetobacter were the predominant bacterial groups. The levels of ethyl acetate, ethyl lactate, and higher alcohols in all brewing processes using the koji exhibited rapid increase in the early stages of fermentation, which stabilized in the later stages, followed by substantial increase after distillation. The results of metagenomic and redundancy analyses of samples taken during the brewing processes indicated that Saccharomyces from the koji was closely related to the production of ethyl acetate, ethyl lactate, and higher alcohols. This study provides a basis for the quality improvement and application of commercial koji.

The quality control of Baijiu is necessary including ethanol content. In this work, red-emitted carbon quantum dots based on p-phenylenediamine (PPD-CQDs) were fabricated for accurate determination of ethanol in Baijiu. The good linear response of PPD-CQDs to ethanol-water solution (E-Ws; 20-80 vol%) offered the potential for ethanol determination in practice. However, further application of this procedure to Baijiu resulted in a certain deviation. After excluding interference from most of the ingredients involved, a simple pH correction on Baijiu made application of the process practicable. The red-emission of PPD-CQDs supported analysis of Baijiu with different flavors and ethanol monitoring. Therefore, a quick-response fluorescence method was established for Baijiu ethanol determination; this method can be applied to the many varieties of Chinese Baijiu available and also has potential for use in other alcoholic beverages.

Developing highly sensitive fluorescent probe for Al3+ and H2O detection is highly desirable, due to aluminum toxicity poses a significant threat to public health. On the other hand, the determination of water content holds immense significance in a wide range of fields such as food processing, pharmaceutical manufacturing. In this paper, a novel acylhydrazone-based fluorescent probe P was successfully synthesized and characterized for the sequential detection of Al3+ and water in alcohols. The probe P exhibited a remarkable \"turn-on\" response towards Al3+ by emitting yellow fluorescence at 567 nm, with high selectivity and large Stokes shift (147 nm). Meanwhile, the in situ formed P-Al3+ complex demonstrated significant solvatofluorochromic characteristic, which could be utilized as a second probe for detecting water via fluorescence quenching with low detection limit in alcohols (0.008%, methanol; 0.013%, ethanol; 0.013%, isopropanol; 0.037%, n-butanol; vol.%) and acetonitrile (0.072%, vol.%). Moreover, the P-Al3+ complex was able to detect the alcoholic strength of Chinese Baijiu without the interference of other alcohols, providing an excellent recovery rate (100.0-107.0%). Different Chinese Baijius, with various alcoholic strength, could be distinguished by simple test strips. Furthermore, the P-Al3+ complex could also analyze the water content in organic solvents .