This study investigated the physicochemical properties,enzyme activities,volatile flavor components,microbial communities,and sensory evaluation of high-temperature Daqu(HTD)during the maturation process,and a standar...This study investigated the physicochemical properties,enzyme activities,volatile flavor components,microbial communities,and sensory evaluation of high-temperature Daqu(HTD)during the maturation process,and a standard system was established for comprehensive quality evaluation of HTD.There were obvious changes in the physicochemical properties,enzyme activities,and volatile flavor components at different storage periods,which affected the sensory evaluation of HTD to a certain extent.The results of high-throughput sequencing revealed significant microbial diversity,and showed that the bacterial community changed significantly more than did the fungal community.During the storage process,the dominant bacterial genera were Kroppenstedtia and Thermoascus.The correlation between dominant microorganisms and quality indicators highlighted their role in HTD quality.Lactococcus,Candida,Pichia,Paecilomyces,and protease activity played a crucial role in the formation of isovaleraldehyde.Acidic protease activity had the greatest impact on the microbial community.Moisture promoted isobutyric acid generation.Furthermore,the comprehensive quality evaluation standard system was established by the entropy weight method combined with multi-factor fuzzy mathematics.Consequently,this study provides innovative insights for comprehensive quality evaluation of HTD during storage and establishes a groundwork for scientific and rational storage of HTD and quality control of sauce-flavor Baijiu.展开更多
A yeast strain had been isolated by dilution-plate from the Daqu samples in our study. The strain was identified as a strain of Rhodotorula aurantiaca through observation of its morphological features, micromorphologi...A yeast strain had been isolated by dilution-plate from the Daqu samples in our study. The strain was identified as a strain of Rhodotorula aurantiaca through observation of its morphological features, micromorphological observation and biolog identification system.展开更多
Abstract： Daqu distiller＇s grains were co-fermented as raw materials by Trichoderma.koningii and Trichosporon cutaneum to produce microbial oils, which can provide raw materials for bio-diesel development. The singl...Abstract： Daqu distiller＇s grains were co-fermented as raw materials by Trichoderma.koningii and Trichosporon cutaneum to produce microbial oils, which can provide raw materials for bio-diesel development. The single factor tests were used to investigate the effects of ratio of strains, inoculum size, culture temperature and culture time on the production of microbial oils. The best processing conditions were obtained by orthogonal test through measuring the content of microbial oils in product. The result shows that the microbial oils content of the co-fermented product under the ratio of Trichoderma.koningii to Trichosporon cutaneum of 1：1, the inoculum size of strains of 11% at 28 ℃ for 6 d is 7.15 g/L. It is shown that the production of microbial oils co-fermented by Trichoderma.koningii and Trichosporon cutaneum with Daqu distiller＇s grains is possible. The research provides a new idea for the reuse of Daqu distiller＇s grains and also provides a new way for the development of microbial oils.展开更多
The quality and aroma of strong-flavor Baijiu are mainly dependent on Daqu,pit mud(PM),and the interaction of both.However,little is known about how their combination patterns affect the microbiome and metabolome of Z...The quality and aroma of strong-flavor Baijiu are mainly dependent on Daqu,pit mud(PM),and the interaction of both.However,little is known about how their combination patterns affect the microbiome and metabolome of Zaopei,especially the metabolic function of rare taxa.Here,an experiment on industrial size was designed to assess the effects of 6 combinations(3 kinds of Daqu×2 kinds of PM)on the composition and assembly of different taxa,as well as the flavor profile.The results showed that Zaopei's microbiota was composed of a few abundant taxa and enormous rare taxa,and rare bacterial and abundant fungal subcommunities were significantly affected by combination patterns.The assembly processes of abundant/rare taxa and bacterial/fungal communities were distinct,and environmental changes mediated the balance between stochastic and deterministic processes in rare bacteria assembly.Furthermore,specific combination patterns improved the flavor quality of Zaopei by enhancing the interspecies interaction,which was closely related to rare taxa,especially rare bacteria.These findings highlighted that rare bacteria might be the keystone in involving community interaction and maintaining metabolic function,which provided a scientific foundation for better understanding and regulating the brewing microbiota from the viewpoint of microbial ecology.展开更多
Daqu is the fermenting starter in Chinese Baijiu brewing,contributing functional microorganisms,enzymes and flavor substances to the grain fermentation.Traditional daqu is produced in open environment where environmen...Daqu is the fermenting starter in Chinese Baijiu brewing,contributing functional microorganisms,enzymes and flavor substances to the grain fermentation.Traditional daqu is produced in open environment where environmental factors and microbiota are critical to daqu and Baijiu quality.Mechanization is the direction of Baijiu production development.In this study,we investigated the mechanism of the effect of mechanized environment and manufacturing process on daqu production.Many functional microorganisms(e.g.Acetobacter,lactic acid bacteria and yeast)were distributed in the process environment,including indoor air,tube and equipment surfaces,which contributed to the initial bacterial/fungal composition in daqu(71.62%/28.47%)along with mature daqu powder(21.1%/61.65%).Our results also showed daqu microbiota formation was influenced by both stochastic and deterministic processes.The initial microorganisms produced large amounts of organic acids(19.24 g/kg)and bioheat(58.3◦C)during early fermentation stage,leading to a rapid temperature rise and water loss under the stacking process.Mature daqu powder mainly provided thermophilic microorganisms for fermentation stages during and after temperature rise,including Thermoactinomyces,Thermoascus,Thermomyces,Rhizomucor and Rhizopus,which produced enzymes and amino nitrogen for Baijiu fermentation,also ensuring stable microbiota among process batches.This work revealed the origin of the microbial community of strong-flavor daqu and showed that ecological environment suitable for daqu fermentation was created during the long-term continuous production process by adding mature daqu powder during daqu brick making and sprinkling it in the workshop,by which product quality was guaranteed.展开更多
High content of ethyl acetate may destroy the typical flavor of Chinese Nong-xiang Baijiu.Formation of ethyl acetate is closely related to its precursor acetic acid from Daqu starter in the fermentation process of Chi...High content of ethyl acetate may destroy the typical flavor of Chinese Nong-xiang Baijiu.Formation of ethyl acetate is closely related to its precursor acetic acid from Daqu starter in the fermentation process of Chinese Baijiu.In this study,the potential functional microbiota responsible for production of acetic acid was explored by correlation analysis and function prediction in Nong-xiang Daqu from different geographical regions.Our results revealed that the microbial community of Daqu starter was correlated with its acetic acid content.In addition,the relative abundances of Weissella,Lactobacillus,Bacillus,Kroppenstedtia,and Pichia were higher in the Daqu with high content of acetic acid.Furthermore,Acetobacter,Weissella,Lactobacillus,Pichia,Candida,and Rhizo-mucor were significantly(p<0.01)and positively correlated with acetic acid.Meanwhile,higher abundances of most genes that encoding enzymes participated in glycolysis and pentose phosphate pathways for acetic acid synthesis,were observed by PICRUSt2 approach in the Daqu starters with high content of acetic acid.Taken together,Acetobacter,Weissella,Lactobacillus,Pichia,and Candida were determined as the potential functional microbiota for producing acetic acid in Nong-xiang Daqu starters.These results provided evidence of microbiota for revealing the possible causes of high acetic acid and ethyl acetate in Nong-xiang Baijiu brewing process,and laid theoretical foundation for regulation of Baijiu fermentation by functional microbiota.展开更多
There is increasing interest in the utilization of tartary buckwheat(TB)for making various fermented foods due to its unique starch structure and functional features.However,studies on Daqu starter produced with TB as...There is increasing interest in the utilization of tartary buckwheat(TB)for making various fermented foods due to its unique starch structure and functional features.However,studies on Daqu starter produced with TB as a raw material are lacking.This study aimed to compare the differences between conventional low-temperature Daqu(NDQ;65%barley and 35%pea)and Daqu made with TB(BDQ;55%barley,30%pea,and 15%TB)in physicochemical properties,microbial communities,and volatile and nonvolatile metabolites.Compared with NDQ,BDQ exhibited higher saccharifying power,liquefying power,acid protease activity,and lower pH value.High-throughput sequencing revealed that the microbial community structure of NDQ and BDQ had significant differences.NDQ were enriched in Kroppenstedtia,Bacillus,Saccharomycopsis,Issatchenkia,Cladosporium,and Aspergillus,while BDQ were dominated by Kroppenstedtia,Comamonas,Pseudomonas,Acinetobacter,Rhizopus,and Saccharomycopsis.There were notable distinctions in volatile and nonvolatile metabolomic profiles between NDQ and BDQ.The physicochemical differences between NDQ and BDQ were driven by their different microbiota,which also led to the inconsistency of their metabolite profiles.The bacterial community was significantly correlated with pH and acid protease activity,whereas the fungal community was only strongly correlated with saccharifying power.In addition,the correlation network demonstrated that the resident dominant microbes in Daqu had strong connections to numerous important volatile and nonvolatile compounds.This study provided a detailed insight into the microbiome characteristics that differ between the NDQ and BDQ,and it can be helpful to develop a TB-based starter applied in making traditional fermented foods.展开更多
文摘This study investigated the physicochemical properties,enzyme activities,volatile flavor components,microbial communities,and sensory evaluation of high-temperature Daqu(HTD)during the maturation process,and a standard system was established for comprehensive quality evaluation of HTD.There were obvious changes in the physicochemical properties,enzyme activities,and volatile flavor components at different storage periods,which affected the sensory evaluation of HTD to a certain extent.The results of high-throughput sequencing revealed significant microbial diversity,and showed that the bacterial community changed significantly more than did the fungal community.During the storage process,the dominant bacterial genera were Kroppenstedtia and Thermoascus.The correlation between dominant microorganisms and quality indicators highlighted their role in HTD quality.Lactococcus,Candida,Pichia,Paecilomyces,and protease activity played a crucial role in the formation of isovaleraldehyde.Acidic protease activity had the greatest impact on the microbial community.Moisture promoted isobutyric acid generation.Furthermore,the comprehensive quality evaluation standard system was established by the entropy weight method combined with multi-factor fuzzy mathematics.Consequently,this study provides innovative insights for comprehensive quality evaluation of HTD during storage and establishes a groundwork for scientific and rational storage of HTD and quality control of sauce-flavor Baijiu.
文摘A yeast strain had been isolated by dilution-plate from the Daqu samples in our study. The strain was identified as a strain of Rhodotorula aurantiaca through observation of its morphological features, micromorphological observation and biolog identification system.
基金Project(10A110) supported by Hunan Provincial Education Department of ChinaProject(2010JT4055) supported by Hunan Provincial Science & Technology Department of China
文摘Abstract： Daqu distiller＇s grains were co-fermented as raw materials by Trichoderma.koningii and Trichosporon cutaneum to produce microbial oils, which can provide raw materials for bio-diesel development. The single factor tests were used to investigate the effects of ratio of strains, inoculum size, culture temperature and culture time on the production of microbial oils. The best processing conditions were obtained by orthogonal test through measuring the content of microbial oils in product. The result shows that the microbial oils content of the co-fermented product under the ratio of Trichoderma.koningii to Trichosporon cutaneum of 1：1, the inoculum size of strains of 11% at 28 ℃ for 6 d is 7.15 g/L. It is shown that the production of microbial oils co-fermented by Trichoderma.koningii and Trichosporon cutaneum with Daqu distiller＇s grains is possible. The research provides a new idea for the reuse of Daqu distiller＇s grains and also provides a new way for the development of microbial oils.
基金supported by the Cooperation Project of Luzhou Laojiao Co.,Ltd.Sichuan University (21H0997)。
文摘The quality and aroma of strong-flavor Baijiu are mainly dependent on Daqu,pit mud(PM),and the interaction of both.However,little is known about how their combination patterns affect the microbiome and metabolome of Zaopei,especially the metabolic function of rare taxa.Here,an experiment on industrial size was designed to assess the effects of 6 combinations(3 kinds of Daqu×2 kinds of PM)on the composition and assembly of different taxa,as well as the flavor profile.The results showed that Zaopei's microbiota was composed of a few abundant taxa and enormous rare taxa,and rare bacterial and abundant fungal subcommunities were significantly affected by combination patterns.The assembly processes of abundant/rare taxa and bacterial/fungal communities were distinct,and environmental changes mediated the balance between stochastic and deterministic processes in rare bacteria assembly.Furthermore,specific combination patterns improved the flavor quality of Zaopei by enhancing the interspecies interaction,which was closely related to rare taxa,especially rare bacteria.These findings highlighted that rare bacteria might be the keystone in involving community interaction and maintaining metabolic function,which provided a scientific foundation for better understanding and regulating the brewing microbiota from the viewpoint of microbial ecology.
文摘该研究通过顶空固相微萃取-气相色谱-质谱联用技术(headspace-solid phase microextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS)和高通量测序技术系统解析了3种大曲的特征香气化合物及微生物群落结构。研究发现,3种大曲分为以吡嗪类或以酯类化合物为主体风味两类。采用多元统计分析并根据变量投影重要性指标(variable importance in the projection,VIP)分析共鉴定出31种特征香气化合物。利用高通量测序技术对大曲的细菌群落结构进行解析,结合相关性分析,从多个维度判定了其核心微生物为火山渣芽孢杆菌属(Scopulibacillus)和芽孢杆菌属(Bacillus),其与多种吡嗪类、酚类、醇类等特征风味物质显著相关。通过分离培养及固态发酵实验探究其风味代谢能力,核心微生物的应用结果表明大曲细菌菌群的生物量及吡嗪类化合物的含量明显提升,改变了大曲的香气组成,进一步证实了其对大曲主体风味的调控功能。该研究在实现大曲风味定向调控、提升白酒品质方面具有重要意义。
基金This work was financially supported by the National Natural Science Foundation of China(22138004)the first phase of the connotation construction of the 14th Five-Year Plan of Tibetan medicine(2021ZYYGH008)Sichuan post-doctoral program.
文摘Daqu is the fermenting starter in Chinese Baijiu brewing,contributing functional microorganisms,enzymes and flavor substances to the grain fermentation.Traditional daqu is produced in open environment where environmental factors and microbiota are critical to daqu and Baijiu quality.Mechanization is the direction of Baijiu production development.In this study,we investigated the mechanism of the effect of mechanized environment and manufacturing process on daqu production.Many functional microorganisms(e.g.Acetobacter,lactic acid bacteria and yeast)were distributed in the process environment,including indoor air,tube and equipment surfaces,which contributed to the initial bacterial/fungal composition in daqu(71.62%/28.47%)along with mature daqu powder(21.1%/61.65%).Our results also showed daqu microbiota formation was influenced by both stochastic and deterministic processes.The initial microorganisms produced large amounts of organic acids(19.24 g/kg)and bioheat(58.3◦C)during early fermentation stage,leading to a rapid temperature rise and water loss under the stacking process.Mature daqu powder mainly provided thermophilic microorganisms for fermentation stages during and after temperature rise,including Thermoactinomyces,Thermoascus,Thermomyces,Rhizomucor and Rhizopus,which produced enzymes and amino nitrogen for Baijiu fermentation,also ensuring stable microbiota among process batches.This work revealed the origin of the microbial community of strong-flavor daqu and showed that ecological environment suitable for daqu fermentation was created during the long-term continuous production process by adding mature daqu powder during daqu brick making and sprinkling it in the workshop,by which product quality was guaranteed.
基金funded by the Sichuan Province Key Research and Development Project(2021YFS0340)Doctoral Scientific Fund Project of Southwest University of Science and Technology(20zx7130)Open Fund of Key Laboratory in Luzhou(NJ202201)。
文摘High content of ethyl acetate may destroy the typical flavor of Chinese Nong-xiang Baijiu.Formation of ethyl acetate is closely related to its precursor acetic acid from Daqu starter in the fermentation process of Chinese Baijiu.In this study,the potential functional microbiota responsible for production of acetic acid was explored by correlation analysis and function prediction in Nong-xiang Daqu from different geographical regions.Our results revealed that the microbial community of Daqu starter was correlated with its acetic acid content.In addition,the relative abundances of Weissella,Lactobacillus,Bacillus,Kroppenstedtia,and Pichia were higher in the Daqu with high content of acetic acid.Furthermore,Acetobacter,Weissella,Lactobacillus,Pichia,Candida,and Rhizo-mucor were significantly(p<0.01)and positively correlated with acetic acid.Meanwhile,higher abundances of most genes that encoding enzymes participated in glycolysis and pentose phosphate pathways for acetic acid synthesis,were observed by PICRUSt2 approach in the Daqu starters with high content of acetic acid.Taken together,Acetobacter,Weissella,Lactobacillus,Pichia,and Candida were determined as the potential functional microbiota for producing acetic acid in Nong-xiang Daqu starters.These results provided evidence of microbiota for revealing the possible causes of high acetic acid and ethyl acetate in Nong-xiang Baijiu brewing process,and laid theoretical foundation for regulation of Baijiu fermentation by functional microbiota.
基金supported by the Natural Science Foundation of China(Grant No.31972975).
文摘There is increasing interest in the utilization of tartary buckwheat(TB)for making various fermented foods due to its unique starch structure and functional features.However,studies on Daqu starter produced with TB as a raw material are lacking.This study aimed to compare the differences between conventional low-temperature Daqu(NDQ;65%barley and 35%pea)and Daqu made with TB(BDQ;55%barley,30%pea,and 15%TB)in physicochemical properties,microbial communities,and volatile and nonvolatile metabolites.Compared with NDQ,BDQ exhibited higher saccharifying power,liquefying power,acid protease activity,and lower pH value.High-throughput sequencing revealed that the microbial community structure of NDQ and BDQ had significant differences.NDQ were enriched in Kroppenstedtia,Bacillus,Saccharomycopsis,Issatchenkia,Cladosporium,and Aspergillus,while BDQ were dominated by Kroppenstedtia,Comamonas,Pseudomonas,Acinetobacter,Rhizopus,and Saccharomycopsis.There were notable distinctions in volatile and nonvolatile metabolomic profiles between NDQ and BDQ.The physicochemical differences between NDQ and BDQ were driven by their different microbiota,which also led to the inconsistency of their metabolite profiles.The bacterial community was significantly correlated with pH and acid protease activity,whereas the fungal community was only strongly correlated with saccharifying power.In addition,the correlation network demonstrated that the resident dominant microbes in Daqu had strong connections to numerous important volatile and nonvolatile compounds.This study provided a detailed insight into the microbiome characteristics that differ between the NDQ and BDQ,and it can be helpful to develop a TB-based starter applied in making traditional fermented foods.
