The quality and yield of Luzhou-flavor liquor is directly determined by the quality of pit mud from the Luzhou-flavor liquor distillery. The aged pit mud produces the good quality liquor while new pit mud dose not. The aim of this study was to investigate the prokaryotic community diversity between new and aged pit mud by high-throughput sequencing technique and the real-time quantitative PCR (qPCR) assay. Results indicated that diversities of prokaryotic community in new pit muds were higher than those in aged pit muds. The abundances of the phylum Bacteroidetes in aged pit muds were significantly (P < 0.05) higher than those in new pit muds, while the abundances of the genus Lactobacillus and Bacillus changed in the opposite trend. Additionally, the quantity of Clostridium Kluyveri in aged pit mud was higher than that in new pit mud. Bacteroidetes, Lactobacillus, Bacillus and C. kluyveri may be the potential indicator-like microbe to distinguish new and aged pit mud fast, conveniently and reliably by qPCR. Results presented in this study provide specific understanding of the differences in prokaryotic community between the new and aged pit muds, and have laid initial foundation for identifying aged pit mud and for advancing pit mud aged.

Fresh raw liquors distilled from Zaopei fermented in new, trend to‐be aged and aged pit mud, labelled as N1 and N2, T1 and T2, and A1 and A2, respectively, were analysed by sensory evaluation, two‐dimensional gas chromatography/time‐of‐flight mass spectrometry with combined principal component analysis, gas chromatography–flame ionization detection, liquid chromatography–mass spectrometry with combined hierarchical cluster analysis, and partial least square–discrimination analysis. Results showed that samples had the same grouping situations by each method: the N‐group containing N1 and N2; the T‐group containing T1 and T2; and the A‐group containing A1 and A2. The specific markers for the N‐group liquors were 2‐butanol and butanoic acid, and those for the A‐group were 1‐hexanol, ethyl pentanoate and 2‐pentanone. The threshold contents of 1‐hexanol, ethyl pentanoate, and 2‐pentanone for the A‐group liquors were 1207.95 ± 252.59, 469.89 ± 73.08 and 1105.12 ± 141.91 mg L−1, while those of 2‐butanol and butanoic acid for the N‐group liquors were 215.66 ± 179.50 and 430.65 ± 60.47 mg L−1, respectively. The results from modern chromatographic techniques and chemometric analyses verify the correctness of the traditional sensory evaluation used in controlling the quality of Chinese liquor, contribute to further studies related to the aroma and flavour of Chinese Luzhou‐flavour of fresh raw liquors and may provide significantly helpful thresholds in distinguishing Chinese Luzhou‐flavour fresh raw liquors distilled from Zaopei fermented in new, trend to‐be aged and aged pit muds. Copyright © 2017 The Institute of Brewing & Distilling

Modern techniques and metrology tools verified the correctness of the traditional sensory evaluation used in controlling the quality of pit mud, and will contribute to distinguishing different maturity levels of Chinese Luzhou-flavoured pit muds.

Distillers' grains are a co-product of ethanol production. In China, only a small portion of distillers' grains have been used to feed the livestock because the amount was so huge. Nowadays, it has been reported that the distillers' grains have the potential for fuel ethanol production because they are composed of lignocelluloses and residual starch. In order to effectively convert distillers' grains to fuel ethanol and other valuable production, sodium hydroxide pretreatment, step-by-step enzymatic hydrolysis, and simultaneous saccharification and fermentation (SSF) were investigated. The residual starch was first recycled from wet distillers' grains (WDG) with glucoamylase to obtain glucose-rich liquid. The total sugar concentration was 21.3 g/L, and 111.9% theoretical starch was hydrolyzed. Then the removed-starch dry distillers' grains (RDDG) were pretreated with NaOH under optimal conditions and the pretreated dry distillers' grains (PDDG) were used for xylanase hydrolysis. The xylose concentration was 19.4 g/L and 68.6% theoretical xylose was hydrolyzed. The cellulose-enriched dry distillers' grains (CDDG) obtained from xylanase hydrolysis were used in SSF for ethanol production. The ethanol concentration was 42.1 g/L and the ethanol productivity was 28.7 g/100 g CDDG. After the experiment, approximately 80.6% of the fermentable sugars in WDG was converted to ethanol.

The caproic acid-producing bacterial consortium (CAPBC) J 30 , isolated from Chinese Luzhou-flavored liquor distillery's pit mud, produces caproic acid as a metabolite. Constructed a 16S rDNA gene clone library and analyzed amplified ribosomal DNA restriction analysis, Clostridium genus was found predominating in CAPBC J 30 and C. kluyveri was the chief contributor to its caproic acid-producing ability. Then based on the Daqu extraction medium, effects of different carbon sources, nitrogen sources and growth factors on the caproic acid-producing ability were investigated, among which six key factors were chosen and optimized by Taguchi design. The estimated optimal medium was the Daqu extraction medium added 10 g•l _ 1 sodium acetate, ethanol 15 ml•l _ 1 , liquor tailing 15 ml•l _ 1 , urea 3 g•l _ 1 , yellow mud extraction 1 ml•l _ 1 , and (NH 4) 2 SO 4 0.5 g•l _ 1. After cultivated in this optimized medium for 15 days at 37℃, the caproic acid yield was up to 5024.11 mg•l _ 1. This optimal medium will help to produce high caproic acid of CAPBC J 30 to circumvent bottlenecks encountered in the high effective and adaptable ingredients in the field of Chinses Luzhou-flavored liquor manufacture.