| Shanxi aged vinegar is traditional solid-state fermented food,which is taking sorghum and Daqu as row materials and Starter,respectively.Here the whole brewing process of Shanxi aged vinegar was taken as sample system,reseached the brewing mechanism by microorganisms of Shanxi aged vinegar.We performed Illumin Mi Seq sequencing to trace the dynamics of microbial community structure and diversity during the whole fermentation of Shanxi aged vinegar,firstly.And then,the composition and dynamic changes of physical and chemical factors and flavor(organic acids and volatile aroma compounds)during whole brewing process of Shanxi aged vinegar were analyzed by modern analytical instrument(High performance liquid chromatography and Gas chromatography-mass spectrometry).Finally,the multivariate statistical analysis method was used to find the correlation among vinegar microbes,physicochemical factors and flavor substances,searched for microbial flora related to physical and chemical factors and flavor.The dynamics of microbial community succession during the whole fermentation stages were investigated by Illumina Miseq High-throughput sequencing.The resuts showed that the sequences were distributed among 5 bacterial phyla of Firmicutes(81.24%),Proteobacteria(15.78%),Actinobacteria(0.10%),Bacteroidetes(0.16%)and Cyanobacteria(0.65%).A total 12 bacterial genra were identified,mainly Weissella(28.01%)and Lactobacillus(59.48%).Weissella thrived first and then declined with the relative abundance of 3.01% at the end of alcohol fermentation.Lactobacillus gradually proliferated to 94.61%.At the acetic acid fermentation,Acetobacter(65.37%)and Lactobacillus(29.15%)were the mainly bacterial genra.Lactobacillus hold higher relative abundance in first 3 days and then decreased.Howere,Acetobacter increased to 87.58% at end of acetic acid fermentation.The resuts showed that the sequences were distributed among 5 bacterial phyla of Ascomycota(81.24%),Basidiomycota(15.78%)and Zygomycota(0.65%).A total 28 fungal genra were identified,mainly Candida(88.39%)and Trichoderma(2.01%).Candida hold higher relative abundance during alcohol fermentation,Trichoderma gradually decreased to 2.97%.Alternaria(24.81%),Candida(20.49%),Monilia(12.36%)and Cryptococcus(7.93%)were the mainly bacterial genra in acetic acid fermentation.Alternaria tended to increase firstly,and then decline.The relative abundance of Candida was 15.42 at end of acetic acid fermentation.Monilia was detected from 9 days of acetic acid fermentation,and its gradually proliferated to 35.11%.Cryptococcus decreased to 5.97% at end of acetic acid fermentation.The dynamics of physical and chemical factors during brewing process of Shanxi aged vinegar were monitored.At the alcohol fermentation,p H reducing sugar and soluble solids were decreased,the content of alcohol and acidity were increased to 5.7% and 1.34 g/100 g,respectively.The dynamics of flavor during the whole brewing process were investigated by chromatography.The content of total organic acids was increased from 0.5050 g/100 g at AF0 to 1.5229 g/100 g at AF8,lactic acid accounts for 58.88% of total organic acid content,acetic acid,oxalic acid,pyruvic acid,citric acid and succinic acid were ended to increase.Also,a total 66 volatile aroma compounds were detected in the alcohol fermentation,the relative contents of ester,alcohol and volatile acid reached 51.18%?17.21% and 0.77%,respectively.The acidity was increased to 4.66 g/100 g sharply,Non-volatile acid,amino nitrogen content and temperature tended to increase firstly,and then decline.Acetic acid and lactic acid were increased from 0.0950 g/100 g and 0.2343 g/100 g at AAF0 to 0.9530 g/100 g and 0.6775 g/100 g at AAF12,accounts for 64.43% of total organic acid content.35 kinds of ester,7 kinds of alcohol and volatile acid reached 53.26%?9.35% and 14.5%,respectively.The physical and chemical factors during fuming stage and leaching vinegar of Shanxi aged vinegar were monitored.Non-volatile acid and acidity tended to increase.The content of acetic acid declined,however lactic acid inriched.The relative contents of ester,alcohol and volatile acid declined,furfural and tetramethyl pyrazine increased rapidly.In leaching vinegar,12 kinds of ester,3 kinds of alcohol and 1 kinds of volatile acid,8 kinds of aldehydes and 10 kinds of heterocyclic compounds were detected.The canonical correspondence analysis was used to analyze the association between microbiota and physical and chemical factors during fermentation process.During alcohol fermentation,acidity was positively correlated with Weissella and Lactobacillus in AF4.p H was positively correlated with Pediococcus and Bacillus in AF0.p H and acidity were the dominant environmental factors during acetic acid fermentation,which was positively correlated with Leuconostoc,Lactococcus,Acetobacter and Pantoea.The correlation between flavor and microbiota in the fermentation process of Shanxi aged vinegar was investigated by partial least squares analysis.Lactobacillus was highly correlated with lactic acid,acetic acid,citric acid,pyruvic acid,oxalic acid and succinic acid,Lactococcus and Weissella were associated with tartaric acid and malic acid during alcohol fermentation.Lactobacillus and Acetobacter had correlation with acetic acid,citric acid,oxalic acid,tartaric acid and malic acid during acetic acid fermentation.Pediococcus and Weissella were associated with 3 kinds of ester,Lactobacillus was highly correlated with ethanol and most of ester during alcohol fermentation.Acetobacter,Lactococcus and Weissella were associated with acetic acid,ethyl acetate and acetoin.The association between microbiota and physical and chemical factors was investigated.The results showed that reducing sugar,p H and alcohol were the dominant environmental factors during alcohol fermentation.Alcohol was positively correlated with Candida and Phialemonium,and was negative correlated with reducing sugar during alcohol fermentation.Temperature and non-volatile acid was negative correlated with Davidiella,Bullera and Hannaella.Candida and Fusarium were associated with lactic acid.Candida was correlated with ethanol and ethyl acetate.During acetic acid fermentation,Candida and Moniliella were associated with ethyl acetate and acetoin,Alternaria had contribution to most of ester.The ~1H-NMR fingerprints of the four famous Chinese vinegars in different aging years showed that 28 chemical constituents were identified.10 years Shanxi vinegar aged and 8 years Baoning bran vinegar had high correlation with Trp,Tyr and 5-hydroxymethyl fural.8 years Zhenjiang aged vinegar was associated with acetic acid,pyruvic acid,Tyr and Trp.8 years Yongchun aged vinegar was highly correlated withacetic acid,pyruvic acid,choline,choline phosphate,Glu,Arg,Asp and Gly.Fourier transform infrared fingerprint was identify the main compounds in vinegar.S5,S8,S9,S10 and S13 sensors of electronic nose sensors were sensitive to ethyl acetate,acetic acid,3-methyl butyric acid,tetramethylpyrazine and furfural.S1 was highly correlated with ethyl lactate,benzaldehyde and coconut aldehyde.Sensors S7 and S11 was associated with 2-methyl butyric acid,2-acetylfuran and 3-octanone.Sensors S2 and S4 are highly correlated with acetoin,nonanal and decanal.Four famous Chinese vinegars of different aging years were distinguished by electronic tongue. |
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