Pottery jars are key for Baijiu aging, with their microstructure and macroscopic properties regulating liquor quality. This study investigated three origin-specific pottery jars (P1, P2, P3) for soy sauce-flavored Baijiu, analyzing their corrosion, mechanical and adsorption properties via multiple characterization and test methods. A novel "diffusion-complexation-crystallization-growth" cycle was revealed: iron ions leached from jars form iron oxide/salt crystals in Baijiu, modulating flavor evolution. The jars showed distinct superiorities: P3 had the optimal corrosion resistance (Fe leaching: 0.307 mg/L, P1 the poorest with 6.9 mg maximum mass loss); P2 possessed the largest specific surface area (0.323 m(2)/g), presenting the highest adsorption capacity (25.7 mg/g) and best mechanical stability (8.22% strength loss after corrosion); P1 selectively adsorbed high-boiling-point alcohols and ketones (2-undecanone residue: 10.71 mg/L). All jars followed the pseudo-second-order adsorption model (R-2 > 0.999),adsorption involves a rapid surface diffusion phase and a slow intraparticle diffusion phase; the overall adsorption rate is primarily governed by surface diffusion (liquid film diffusion) and had unique metal ion leaching fingerprints. This study establishes the structure-property-function relationship of pottery jars, providing a theoretical basis for their scientific selection in Baijiu aging.

Heap fermentation is a characteristic stage of sauce-flavor Baijiu production and represents a complex open solid-state fermentation system shaped by gradients in temperature, oxygen availability, and moisture. Rather than a universal model, it is treated here as a well-documented case through which observations from an industrial fermentation can be organized and evaluated. This review synthesizes current knowledge on microbial succession, functional groups, and metabolite formation during heap fermentation and discusses these observations in relation to ecological assembly perspectives. The evidential scope and limitations of commonly used approaches are examined, including amplicon sequencing, quantitative assays, multi-omics analyses, spatial measurements, and modeling methods such as network analysis and reaction-diffusion simulations. Particular attention is given to uncertainties in linking community composition with process behavior and to practical constraints of applying advanced analytical tools in open fermentation environments. Studies have reported that environmental gradients are associated with shifts in microbial populations. Open inoculation, however, contributes variability among batches. Across published reports, some studies report relatively stable fermentation outcomes, although the mechanisms remain unclear. Accordingly, heap fermentation is discussed as a case-based context for a broader question relevant to many solid-state fermentations: why similar operating conditions yield reproducible outcomes in some cases but variable results in others. The review organizes available evidence, highlights current limitations and identifies key questions that may require further investigation.

This study employed a multi-technique approach to explore the regional differentiation of sauce aroma baijiu (SAB) within the core production areas of the Chishui River Basin. Sensory analysis revealed significant regional differences: right bank (Guizhou) samples showed stronger sauce, qu, roasted, grain, and acidic aromas, while left bank (Sichuan) samples exhibited more intense fruity, floral, and grass notes. Orthogonal partial least squares-discriminant analysis (OPLS-DA) confirmed clear regional differentiation. Aroma recombination experiments demonstrated that the overall aroma profile, especially the characteristic “sauce” aroma, results from the combined contribution of compounds with an odor activity value (OAV ≥ 1), those with OAV < 1, and non-volatile organic acids. Through integrated analysis of OAV, variable importance in projection (VIP > 1), and correlation coefficients, 20 key regional aroma markers were identified that effectively explain the sensory differentiation patterns. These findings provide a scientific foundation for quality control and geographical origin authentication of SAB.

Moderate alcohol consumption has been suggested to alleviate anxiety and depression; however, it remains unclear whether Luzhou-flavor baijiu (LFB) exerts similar effects and what underlying mechanisms may be involved. To investigate this, we established a chronic restraint stress (CRS)-induced depression model in C57BL/6 mice (in vivo) and a corticosterone-induced depressive-like cell injury model in HT22 hippocampal neurons (in vitro). Behavioral assessments revealed that LFB significantly ameliorated depressive-like behaviors in CRS-exposed mice. Biochemical analyses indicated that LFB reduced Tyr1474 phosphorylation of the GluN2B subunit of N -methyl-D-aspartate receptors (NMDARs) and downregulated the downstream NMDAR cascade, specifically, by suppressing neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS) gene expression, reducing nitric oxide (NO) production, attenuating soluble guanylate cyclase (sGC) activity, and decreasing cyclic guanosine monophosphate (cGMP) levels. These findings suggest that LFB exerts protective effects against CRS-induced depressive phenotypes, likely by modulating the NMDAR-nNOS/iNOS-NO-sGC-cGMP signaling pathway. This provides a mechanistic basis for understanding its potential role in depression-related conditions.

Understanding the multi-scale structure of sorghum starch and sugar profile in different stages of solid-state stacking fermentation is essential for stabilizing the production of Sauce-flavor Baijiu. It was revealed that steaming induced starch gelatinization and then cooling facilitated the formation of V-type crystalline complexes, which are beneficial for managing the fermentation efficiency. During fermentation, amorphous regions were preferentially degraded, leading to the rapid accumulation of glucose (from 1.34 μg/mg to 28.84 μg/mg) and maltose (from 0.00 μg/mg to 2.94 μg/mg) at an early stage. Subsequently, the crystalline regions (relative crystallinity decreased to 12.03%) and long-chain fragments (content of longer amylose chains decreased to 10.70%) of sorghum starch were further hydrolyzed. This process was more pronounced in the center of the pile due to the more intense acid-enzyme synergistic degradation, resulting in spatial heterogeneity. These findings provide insights for improve brewing processes and product quality of Sauce-flavor Baijiu.

The identification of characteristic volatile compounds in Doubanjiang is of great significance for aroma analysis. In this study, the flavor components of Pixian Doubanjiang at different stages were systematically detected by using flavoromics techniques and quantum mechanics. The results suggested that electronic nose combined with OPLS-DA model effectively distinguished the samples with different fermentation stages. Linalool, phenylacetaldehyde, ethyl phenylacetate, ethyl decanoate, phenethyl ethanol and methyl linoleate were identified as the key aroma components based on OAV analysis, with ethyl phenylacetate being considered as the core aroma component. Then, density functional theory (DFT) was employed for the first time to explore the interactions among Doubanjiang flavor substances at the molecular level, which indicated that ethyl phenylacetate interacted with other flavor substances through electrostatic adsorption to achieve a steady state. These results elucidated core aroma components and molecular binding mechanisms governing Doubanjiang flavor, revealing DFT as a predictive framework for flavor modulation.

Conventional evaluation of volatile organic compounds (VOCs) in distilled spirits relies on aqueous ethanol solutions, neglecting matrix effects that critically modulate odor perception. To address this, we developed a Nongxiang-aroma base solution containing 12 compounds to simulate the aroma skeleton of Nongxiangxing baijiu (NXXB), China's most consumed baijiu. Using this physiologically relevant medium, we systematically characterized Qu-aroma in NXXB, the distinctive olfactory signature derived from medium-temperature Daqu (MT-Daqu). Integrative analysis of 37 Qu-aroma VOCs detected in MT-Daqu with volatile profiles in 53 NXXB samples (analyzed via HS-SPME-GC-MS and SBSE-GC-MS/O) identified 17 Qu-aroma active VOCs. Odor thresholds measured in the base solution were up to >200-fold higher than those in ethanol solution, highlighting profound matrix-dependent suppression of aroma potency. By integrating odor activity values (OAVs) with sensory recombination and omission tests, we identified eight key Qu-aroma contributors in NXXB: five direct odorants (isovaleraldehyde, hexanal, 2-methylbutanal, isovaleric acid, 1-hexanol; OAVs > 1) and three modulatory odorants (1-pentanol, benzaldehyde, phenylacetaldehyde; 0.1 < OAV < 1). This study provides a matrix-mimetic, sensory-validated strategy for accurate VOC contribution assessment in complex spirits, advancing baijiu aroma science and quality-oriented innovation.

Stacking fermentation of sauce-flavor Baijiu forms a 3D stratified solid-state bioreactor. The artisanal operations and environment create four microniches, driving yeast community complexity that regulates ethanol production, flavor biosynthesis, microbial balance, and Baijiu quality, yet yeast spatiotemporal dynamics and species-specific flavor roles remain unclear. Using amplicon sequencing and monoculture fermentations, this study mapped yeast distribution and quantified flavor contributions. Yeast richness peaked at 30 genera, dominated by Saccharomycopsis (41.88%), Pichia (17.28%), and Torulaspora (12.58%), with dynamics correlating with moisture, temperature, and acidity (p < 0.05). Key isolates had distinct traits: P. kudriavzevii JNPK produced floral and fruity flavor esters/alcohols, P. manshurica JNPM generated aldehydes, S. fibuligera JNSF produced fewer volatile organic compounds (VOCs), and T. delbrueckii JNTD produced organic acids/tetramethylpyrazine (all critical for aroma). This study provides theoretical support for optimizing yeast application in sauce-flavor Baijiu fermentation.

This review summarizes recent research progress in applying omics technologies, including metagenomics, metatranscriptomics and metaproteomics, to analyze the structure and function of the microbial community in Daqu. In terms of community composition, Daqu harbors a vast reservoir of uncultured microbial resources, with core taxa predominantly consisting of Aspergillus, Bacillus, and Lactobacillus. Regarding community function, studies identify the microbial origins of key metabolic enzymes, such as ester synthases, and elucidate the synergistic role of the microbiota in raw material degradation and flavor formation. With respect to driving factors, omics analyses confirm that environmental factors, such as temperature, influence the fermentation process by regulating microbial transcriptional and protein expression activities. Future research in this field should focus on integrating multi-omics approaches with culturomics, metabolomics, and computational modeling to establish a systematic framework spanning from genes to products and from prediction to regulation. This will facilitate a paradigm shift in Daqu fermentation from empirical control to precision design and performance prediction, thereby deepening the understanding of the principles of Daqu fermentation and enhancing the controllability of the production process.

The utilization of Baijiu distiller’s grains (BDGs), commonly used as a feed ingredient, remains limited due to challenges such as elevated levels of anti-nutritional factors (ANFs), high fiber content, and low protein concentration. Microbial fermentation has been recognized as an effective strategy to improve the nutritional quality of feed substrates. However, its efficacy is highly dependent on process parameters such as temperature. Despite its significance, the effect of temperature on the interaction between microbial communities and the physicochemical properties of BDGs during fermentation remains poorly understood. To address this gap, BDGs were fermented using Bacillus subtilis, Candida utilis, and Geotrichum candidum under varying temperatures. Comprehensive physicochemical analyses combined with high-throughput sequencing of microorganisms were performed to investigate the dynamic changes in both fermentation products and microbial kinetics. The results revealed that the optimal fermentation performance was achieved at 34 °C. At this temperature, compared to untreated BDGs, phytic acid, tannin, and crude fiber levels were significantly reduced by 65.18

Fe2O3 is the most abundant metal oxide in pottery jars after silicon and aluminum oxides, playing a crucial catalytic role in the transformation of flavor compounds during the aging of Baijiu. In this study, three porous Fe2O3 samples (S1, S2, and S3) with varying nano/micron particle ratios were prepared, exhibiting specific surface areas of 3.18, 3.62, and 3.49 m(2). g(-1) and average pore sizes of 11.70, 13.16, and 25.92 nm, respectively. Adsorption kinetic experiments revealed that S3 achieved the highest equilibrium adsorption capacity (16.29 mg/g), with the pseudo-second-order model (R-2 > 0.999) confirming chemisorption as the dominant mechanism. GC-MS analysis demonstrated that Fe2O3 exhibits weak adsorption of esters (e.g., ethyl acetate, with a post-adsorption concentration of only 2.53 mg/L) but selective adsorption of aldehydes and alcohols (e.g., 3-furfural and dimethylsilanediol), potentially facilitating oxidation and hydrolysis reactions. Molecular dynamics simulations indicated significantly higher diffusion rates for water (diffusion coefficient: 2.61 x 10(-7) m(2)/s) and ethanol in 25 & Aring; pores compared to 35 & Aring; pores, suggesting that smaller pores enhance molecular migration and surface catalysis.

Environment serves as the pivotal medium to produce fermented food, with fluctuations in environmental factors exerting a profound impact on the modulation of fermentation microbial communities. Such shifts are crucial for the distinctiveness of fermented food flavor and the variability in quality. Chinese liquor (Baijiu) is one of the typical representatives of spontaneous fermented food. In this review, the multifaceted relationship between regional environmental attributes and the fermentation dynamics of Baijiu was examined, with a spotlight on the strong-flavor, sauce-flavor, and light-flavor varieties. It reveals the influence of regional environmental factors and brewing environmental factors on microbial function and metabolism, which results in the formation of unique flavor characteristics of Baijiu. The 9 main factors affecting the microecology of Baijiu fermentation were further explored, including environmental sensitivity, microbial interactions, biogeographic patterns, and key abiotic factors such as temperature and humidity. Environmental factor management is crucial for controlling microbial community in fermentation. Intelligent detection of the fermentation system is combined with artificial intelligence to realize the digitalization of Baijiu fermentation, with a view to further studying the environmental mechanism or quantitative control relationship of natural fermentation, improving the environmental stability of natural fermentation, and promoting the mechanization and intelligence of fermentation production.

Regulating electron transfer pathway is an effective strategy for enhancing anaerobic digestion (AD) performance. In this study, biochar derived from tree branches, straw, coconut shells, and sewage sludge were used to adjust the AD of liquor wastewater, significantly increasing methane production (from 286.23 mL to 1305.12-1585.54 mL) and soluble chemical oxygen demand (sCOD) removal efficiency (from 23.11 % to 65.88-91.92 %). Feedstock lignin content affected both the specific surface area (SSA) and electron-donating capacity (EDC) of biochars, which exhibited strong positive correlations with cumulative methane production (r =1, p < 0.05). High SSA supported microbial colonization, while EDC facilitated interspecies electron transfer. Biochar enriched for the Firmicutes, Synergistota, and Proteobacteria involved in hydrolysis and acidification processes, enhancing metabolic pathways including fatty acids degradation and aromatic compound degradation. Synergistota and Proteobacteria harbor potentially electroactive bacteria that may facilitate direct inter-species electron transfer (DIET) with Methanosaeta and Methanobacterium to promote DIET pathway. This study provides insights for optimizing biochar preparation in AD systems.

To investigate the distinctive cellar aroma differences between traditional and modern upper steaming distilled strong-aroma type of Baijiu (SAB), Napping-ultraflash profile (Napping-UFP) combined with flavoromics was used. Significant distinctions of the cellar-aroma among 18 different upper steamed distilled samples were observed between LZLJ-T7 and LZLJ-M7 using Napping-UFP. Moreover, 44 odorants with FD >= 9 were identified using comparative aroma extract dilution analysis and further quantified using multiple quantitative techniques. Among them, 28 odorants with OAVs >= 1 were identified as important. In addition, 18 key discriminant mark substances were identified through partial least squares discriminant analysis. Further verification using aroma recombination and omission identified 17 key aroma compounds in LZLJ-T7 and 14 in LZLJ-M7. Partial least squares regression revealed ethyl hexanoate, ethyl 3-phenylpropionate, isovaleric acid, dimethyl trisulfide and ethyl caprylate as the primary contributors to the differential cellar aroma between traditional and modern upper steaming distilled SAB.

Driven by health consciousness and shifting consumer preferences, the baijiu market is undergoing a significant trend toward alcohol reduction. However, producing high-quality low-alcohol baijiu (typically <40% vol) presents considerable technical challenges. Key among these are the inevitable turbidity caused by the precipitation of higher fatty acid esters upon dilution, and the fundamental flavor instability characterized by an "increase in acids and decrease in esters" due to ester hydrolysis. This review systematically summarizes the core technical bottlenecks and emerging strategies in this field. It provides a comprehensive analysis of clarification technologies—comparing freeze filtration, adsorption, and membrane separation—and discusses stabilization approaches, including process control, skillful blending, and novel non-conventional techniques. By offering a holistic perspective on balancing visual clarity with flavor integrity and ensuring long-term stability, this review aims to inform and guide the future development of the low-alcohol baijiu industry.

This study investigates the release behavior of ferric oxide (Fe₂O₃) in Baijiu and its regulation of flavor evolution. Kinetics analysis indicated the leaching process follows the shrinking core model (Ea = 44.52 kJ·mol-1), controlled by surface chemical reactions. Fe₂O₃ particles undergo surface erosion and amorphization, eventually recrystallizing into a FeOOH shell to form a core-shell composite structure. Electrochemical tests confirmed that this surface reconstruction alters interfacial electron transfer properties. The leaching of Fe₂O₃ significantly catalyzed pyrazine formation, resulting in a twofold increase in tetramethylpyrazine at 25 °C and a 107% rise in 2,3-dimethyl-5-isopentylpyrazine at 65 °C. The total ester content exhibited a 42.0% decrease under accelerated aging at 65 °C, compared to a 28.4% reduction at 25 °C. The migration and surface reconstruction of Fe₂O₃ facilitate the catalytic evolution of Baijiu compounds, driving the evolution and reshaping of its theoretical aroma profile based on OAV assessment.

1-Propanol is a crucial flavor compound in Jiang-flavor Baijiu, yet the key microbial pathways and environmental factors controlling its synthesis have not been systematically investigated. Using an integrated approach of metagenomics and culture-dependent techniques, this study identified the key microbes, pathways, and factors controlling 1-propanol synthesis. The highest 1-propanol level was detected in first-round base Baijiu, with rapid accumulation during early pit fermentation. Metagenomics revealed the propanoate pathway as the dominant route, primarily contributed by Limosilactobacillus, while Pichia and Saccharomyces were key providers of pyruvate decarboxylase in the citramalate and threonine pathways. Pure-culture validation confirmed that L. panis MR32 predominantly utilizes 1,2-propanediol as the precursor, while yeasts such as P. kudriavzevii 2J2 and S. cerevisiae LB7A prefer the 2-ketobutyrate pathway. Environmental tests revealed optimal 1-propanol production by L. panis MR32 at pH 5.5 and increasing yields with temperature (25-45 °C). In contrast, most yeasts produced the most 1-propanol at 30 °C, beyond which yields declined, with only P. kudriavzevii 2J2 and I. orientalis IO tolerating high lactic acid. Our findings clarify the microbial division of labor and environmental drivers of 1-propanol formation, enabling targeted fermentation control.

Organic acids play crucial roles in both flavor quality and microbial succession of sauce-flavor Baijiu; however, the core microbial drivers responsible for their metabolism remain poorly understood. This study systematically investigated the microbial drivers of organic acid metabolism across six sequential rounds (R1-R6) of heaped fermentation. A total of 24 organic acids were identified, including nine non-volatile organic acids (NVOAs) and 15 volatile organic acids (VOAs). HPLC analysis revealed that the total content of acetic acid and nine NVOAs increased significantly across rounds, rising from 29.35 g/kg in R1 to 66.40 g/kg in R6. Lactic acid was the most abundant NVOA, while acetic acid, isovaleric acid, and hexanoic acid were the primary volatile contributors. Co-occurrence network analysis identified 488 consistently correlated bacterial pairs that clustered into two distinct guilds. Guild 2, mainly comprising Virgibacillus, Kroppenstedtia, Oceanobacillus, and Bacillus, exhibited high abundance (47%-78%) across all rounds and was defined as the core bacterial guild. Spearman correlation analysis revealed that guild 2 was positively correlated with NVOAs (69.41%) but negatively correlated with VOAs (63.02%). Metagenomic analysis reconstructed seven key pathways involved in organic acid biosynthesis. Kroppenstedtia, Lentibacillus, Desmospora, and Oceanobacillus were identified the taxa harboring the genetic potential most frequently detected across multiple pathways, with Kroppenstedtia and Lentibacillus exhibiting the highest gene abundances. These findings provide a theoretical foundation for targeted regulation of organic acid content in sauce-flavor Baijiu production.

To address production challenges in tea processing, freeze-withering was introduced for yellow tea. This study conducted a comprehensive assessment of the sensory quality, volatile compounds and metabolomics characteristics of freeze-withering yellow tea (FYT) and unfrozen withered yellow tea (UYT). The results indicated that the FYT samples contained higher levels of volatile compounds, including (E,E)-3,5-octadien-2-one, 1-octanol, linalool, beta-myrcene, 2,6-dimethyl-3,7-octadiene-2,6-diol, 2-pentylfuran, and phenylethyl alcohol, compared to UYT. Consequently, FYT exhibited more pronounced sweet, woody, and baked aromas. A total of 15 aroma compounds from the two tea samples were identified as key components and integrated into the flavor wheel model. The enhancement of umami, sweetness, and richness in yellow tea was attributed to increased levels of metabolites, including p-Coumaroyl quinic acid, D-Gluconic Acid, Theaflavin 3,3 '-digallate, Theaflavin-3-gallate, Theaflavin, and 9S,12R,13S-Trihydroxy-10E,15Z-octadecadienoic acid. Conversely, the reduction in bitterness was linked to decreased levels of compounds such as Epigallocatechin 3,4 '-di-O-gallate, (-)-gallocatechin gallate, (-)-catechin gallate, and Procyanidin B3. In addition, after freeze-withering, the content of theaflavins in yellow tea increased significantly. In conclusion, the freeze-withering process is demonstrated to enhance the quality of yellow tea, and it provides a one-month buffer period for tea processing, thereby providing a theoretical basis for alleviating the processing pressure of tea in spring.