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Objective: The production process of esterified Monascus bran koji was optimized, and its effect on Luzhou-flavor liquor was explored. Methods: Five strains of Monascus were screened from Daqu, and the esterifying enzyme production ability of the strains was detected by the ester decomposition method. The strain with the most prominent enzyme production ability was selected to prepare Monascus bran koji. The koji-making process was optimized by single factor and orthogonal experiments and applied to liquor production. Results: Among the five strains, the J-3 strain had the strongest ability to produce esterification enzyme. Under the conditions of 50% moisture, 4% inoculation amount, pH 4.0 and 32 ℃ culture temperature, the esterification enzyme activity was as high as 77.78 mg/g bran koji. The bran koji was added to the fermented grains according to different inoculation amounts. Compared with the fermented grains without bran koji, when the inoculation amount of bran koji was 1%, the content of ethyl acetate in the fermented grains increased by 4.84 times, and the content of ethyl caproate increased by 3.55 times. When the inoculation amount was 1.5%, the content of ethyl butyrate increased by 4.72 times. The addition of esterified Monascus bran koji can improve the utilization rate of alcohol and starch, and significantly increase the total ester content in fermented grains. Conclusion: Adding Monascus bran koji to fermented grains according to the appropriate inoculation amount can improve the quality of Luzhou-flavor liquor.

Sub-high temperature Daqu, a traditional solid fermenting agent used in Chinese strong-aroma Baijiu production, is abundant in diverse microorganisms, including bacteria, yeasts, molds, and actinomycetes. Among these, yeasts are pivotal for ethanol production and flavor formation. However, counting yeasts in Daqu is challenging due to interference from molds and bacteria. Antibiotics are employed to inhibit bacterial growth, but there is no practical way to suppress molds without affecting the growth of yeasts. In this study, short-chain carboxylates (C1-C6) were added to the culture medium at various pH conditions to investigate their effects on the growth of molds and yeasts. The results demonstrated distinct inhibitory effects of the short-chain carboxylates, depending on both pH and concentration. Several tested short-chain carboxylates effectively suppressed mold growth on agar plates while leaving yeast growth unaffected. This suggests a simple and feasible method for enhancing the efficiency of yeast isolation and counting in Daqu. Such an approach is valuable for studying yeasts in diverse and complex habitats.

In order to clarify the succession pattern and potential functions of the microbial communities in fermented grains for Nongxiangxing baijiu, high-throughput sequencing was used to investigate the dynamic change of microbial community structure, and the correlations between microbial community structure and physicochemical indicators were analyzed at different fermentation stages. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) was used to predict the potential functions of microbial communities in fermented grains. The results showed that Firmicutes, Proteobacteria, Actinobacteriota, Ascomycota, and Basidiomycota were the dominant phyla in fermented grains. The dominant genera were Lactobacillus, Bacillus, Staphylococcus, Thermoactinomyces, Kazachstania, Wickerhamomyces, Penicillium, Candida, Aspergillus, Meyerozyma, Debaryomyces, with Lactobacillus, Kazachstania and Wickerhamomyces being the absolutely dominant ones. The contents of reducing sugar and starch showed a significantly positive correlation with 8 bacterial genera (P < 0.05). Acidity and moisture content showed a significantly negative correlation with 10 bacterial genera. Some fungi were significantly correlated with physicochemical indicators. PICRUSt analysis showed that the relative abundance of functional enzymes was significantly different at different fermentation stages, and the dominant microorganisms in fermented grains participated in glycolysis, acid metabolism and ethanol synthesis to form a complete metabolic chain, indicating that the microbial community succession of fermented grains could be the major reason for the differences in metabolism at different fermentation stages. The findings of this study would provide a theoretical basis for the study of the metabolic mechanisms of microorganisms used for baijiu brewing.

This study was performed in order to understand the differences in bacterial communities and physicochemical indicators between bottom and wall pit mud for nongxiangxing baijiu. Five physicochemical indicators of pit mud were analyzed. High-throughput sequencing technology was used to investigate the bacterial communities, and correlation analysis was carried out between bacterial communities and physicochemical indicators. The results showed that the pH and catalase activity in bottom pit mud were significantly higher than those in wall pit mud (P < 0.05), while the opposite was true for ammonium nitrogen content (P < 0.05). The dominant bacterial phyla in pit mud were Firmicutes, Bacteroidetes, and Synergistetes. The dominant genera in bottom pit mud were Hydrogenispora, Caproiciproduces, Aminobacterium, and Proteiniphilum, the relative abundance of Hydrogenispora being significantly higher than that in wall pit mud (P < 0.05). The dominant genera in wall pit mud were Capriocipiroducens, Lactobacillus, Syntrophaceticus, and Aminobacterium, the relative abundance of Capriocipiroducens, Lactobacillus and Syntrophaceticus being significantly higher than that in bottom pit mud (P < 0.05). The physicochemical indicators and bacterial communities in bottom and wall pit mud were different. Among the physicochemical indicators, pH had the greatest impact on the bacterial community in bottom pit mud, and Hydrogenispora was the iconic genus of bacteria in pit bottom mud. The relative abundance of enzymes involved in acid metabolism was higher in pit wall mud. In conclusion, there were spatial differences in the bacterial communities between bottom and wall pit mud, which could have an important impact on the fermentation of baijiu.

The unloading effect is an important factor for the failure of surrounding rock in deep underground engineering projects, especially under high-stress conditions. To investigate the deformation and failure characteristics of sandstone at different unloading rates, the evolution law of the surrounding rock stress caused by excavation was clarified. Then, the single-side unloading test of surrounding rock at different unloading rates was conducted using a true triaxial rock mechanics test system. During the test, the acoustic emission (AE) signals were monitored using an AE monitoring system. The test results show that excavation disturbance leads to complete single-side unloading at the boundary of the surrounding rock, and partial single-side unloading occurs as the depth of the surrounding rock increases. The ultimate strength of the sandstone specimen decreases as a power function with the increasing unloading rate. The unloading rock mass is mainly subject to shear failure. However, the increasing unloading rate raises the proportion of tension cracks. The sudden high strain rate on the unloading side can be used as precursor information of rock fracture, which can effectively prevent accidents caused by loss of rock bearing capacity. The AE signal is active and releases less energy in the unloading stage. At this time, the internal fractures are in the development stage, and the energy is still mainly accumulated. The unloading and failure are not synchronized but suffer from the hysteresis effect. Additionally, the AE and the strain rate change on the unloading side are consistent. Due to the hysteresis effect of damage on unloading, anchor bolts (cables) should be installed to support the surrounding rock immediately to compensate for the stress loss caused by excavation in engineering practice.

(Objective) This study aimed to develop the application of Polygonum lapathifolium in Luzhou-flavor Fuqu. (Methods) In the process of making Luzhou-flavor Fuqu, P. lapathifolium was added. The culture conditions such as the addition amount of P. lapathifolium, the inoculation amount of Luzhou-flavor Daqu, the moisture content and the culture time were optimized. The number of bacteria, the number of yeasts and the activity of glucoamylase were used as indicators to determine the optimal culture conditions. Under the optimal process conditions, GC-MS was used to detect the volatile flavor components in Luzhou-flavor Fuqu Baijiu. (Results) When the addition amount of P. lapathifolium was 8%, the inoculation amount of Luzhou-flavor Daqu was 4%, the moisture content was 55%, and the culture time was 48 h, the number of bacteria in Fuqu was 6.22X 107 CFU/g, the number of yeasts was 6.14X 108 CFU/g, and the glucoamylase activity was 671 U/g. 57 and 51 volatile flavor components were detected in Luzhou-flavor Fuqu Baijiu with and without P. lapathifolium. (Conclusion) The addition of P. lapathifolium could improve the quality of Luzhou-flavor Fuqu and enrich the flavor substances of liquor body. [ABSTRACT FROM AUTHOR]

Recent advances in speaker embeddings promote a great development of speaker diarization. However, determining 'who spoke when' in the meeting scenarios is still challenging due to similar speaker voices and unknown speaker quantity. In this paper, this research proposes enhanced discriminative features for speaker diarization, including discriminative speaker-specific features based on Siamese networks, and a speaker re-verification method. With Siamese architecture, SiamTDNN, this research first explores latent representations which is capable of modeling intra-class and inter-class differences between speakers, by training with audio pairs. Then, the re-verification method is introduced with a local-global strategy to identify speakers in a multi-person talking scene. Our method provides a novel speaker embedding with enhanced discriminative power for disambiguated speakers and achieves an elevated upper bound on the number of speakers. The proposed speaker embedding achieved an EER of 1.1% and a minDCF of 0.1192 on VoxCeleb1 for the speaker verification task. Extensive experiments on AiShell-4, ICSI, AMI and VoxConverse demonstrate the effectiveness of the proposed method with an average DER reduction of 3% and an RTF of 0.0792. [ABSTRACT FROM AUTHOR]