Research On The Metabolites And Flavor Of Naturally Fermented Sour Porridge In Inner Mongolia Based On The Change Of Bacterial Community Structure

Taking the naturally fermented sour porridge in Inner Mongolia as the research object,the bacterial community structures in different fermentation stages of the sour porridge were determined by the high-throughput sequencing method,and the correlation analysis between bacteria and physical and chemical indexes,flavor and nutrients was made by the multivariate statistical method.The experimental results were as follows:(1)According to the results of high-throughput sequencing,the composition of bacteria in sour porridge at the genus level was obtained.At the beginning of(2)fermentation(Oh),the relative abundance of Firmicutes accounted for 54.24%of the bacterial flora abundance,Proteobacteria accounted for 18%,and Cyanobacteria accounted for 27.66%.During the fermentation for 6h-36h,the main bacteria were Firmicutes and Proteobacteria.At the beginning of fermentation(Oh),the bacteria were mainly composed of Pediococcus and Lactobacillus at the genus level.Later,the relative abundance of Pediococcus decreased,while that of Lactobacillus increased.In addition to the two dominant genera,there were Cyanobacteria,Enterobacter,Enterococcus,Bacillus,Enterobacter,Clostridium,Streptococcus,and other bacteria with their relative abundance less than 1%.(2)After fermentation,the pH value of sour porridge decreased,and the total acid content increased.The total sugar and protein content increased,while the total fat content decreased.Through the correlation analysis,it was found that there was a positive correlation between pH value and 18 genera including Clostridium,Bacillus,Enterobacter,and Acidobacteria,a negative correlation between protein and 16 genera including Clostridium,Bacillus,Cuprobacter,Shigella,Streptococcus,a positive correlation between total sugar content and Paenibacillus,Bacillus,a positive correlation between total acid content and Lactobacillus,Acinetobacter,and a negatively correlated with clostridium.The change of fat content was positively correlated with Enterococcus and Pediococcus,and negatively correlated with Lactobacillus(|?|>0.5).(3)After fermentation,the content of 9 organic acids in the gruel increased.The highest content was lactic acid(7.06mg),followed by malic acid,oxalic acid,tartaric acid,acetic acid,succinic acid,citric acid,?-ketoglutarate and L-pyroglutamic acid.Correlation analysis showed that the tartaric acid forms positive correlation with Lactobacillus and Acinetobacter and negative correlation with 16 bacterial genus including Clostridium,Bacillus,Cupriavidus,Shigella and Streptococcus;lactic acid had positive correlation with Lactobacillus and Acinetobacter and negative correlation with 14 bacterial genus covering Clostridium,Bacillus,Cupriavidus,Shigella and Streptococcus;oxalic acid presented positive correlation with Lactobacillus and negative correlation with 18 bacterial genus such as Enterobacteriaceae,Rolstonia and Escherichia-Shigella;citric acid was positively related with Lactobacillus and negatively related with Enterobacteriaceae,Rolstonia and Escherichia-Shigella;succinic acid had positive correlation with Lactobacillus and negative correlation with Enterobacter;malic acid was positively related with Lactobacillus and negatively related with Enterobacteriaceae;acetic acid was positive correlation with Lactobacillus and negative correlation with Paenibacillus;?-ketoglutarate presented positive correlation with Acinetobacter while L-pyroglutamic acid presented negative correlation with Acinetobacter.(4)The content of 8 types of vitamins in sour porridge increased with fermentation.The highest content was Biotin(1132.67ug/ml),followed by folate,vitamin B12,vitamin B2,vitamin C,vitamin B5,niacinamide and vitamin B6.Nicotinamide presented positive correlation with Lactobacillus and Enterococcus while negative correlation with 14 bacterial genus including Clostridium,Bacillus,Cupriavidus,Shigella and Streptococcus;folic acid presented positive correlation with Lactobacillus and negative correlation with 12 bacterial genus covering Clostridium,Paenibacillus,Cupriavidus,Shigella and Streptococcus;vitamin B5 presented positive correlation with Lactobacillus and negative correlation with Paenibacillus.(5)During the fermentation,the sourness tended to increase,while saltness and sweetness decreased.Astringency increased in the fermentation process,while bitterness slightly increased.The values of aftertaste-A and aftertaste-B were almost the same.Umami showed a downward trend,and richness remained unchanged during the fermentation.The response values of the sensor 2 W5S(nitrogen oxides)and the sensor 6 W1S(alkanes)changed obviously.Sensor 2 rose with the maximum value at the 30th hour,while sensor 6 decreased and then increased with fermentation.The response value of sensor 7 W1W(inorganic sulfide)and sensor 9 W2W(organic sulfide)rose.The response values of sensor 8 W2S(alcohols,aldehyde ketone)and sensor 10 W3S(long-chain alkanes,aliphatics)of sensor 8 and sensor 10 first decreased,then increased and final decreased.The response value of sensor 1 W1C(aromatic benzene)was basically stable between 1 and 2.The response value of sensor 3 W3C(ammonia,aromatic component),sensor 4 W6S(hydride)and sensor 5 W5C(alkene,polar molecule,aromatic component)were basically the same.Correlation analysis showed that W1C(aromatic component,Benzene)was positively correlated with Enterobacter,W5S(nitrogen oxides)was positively correlated with Lactobacillus and Acinetobacter,the same kind of bacillus was negatively correlated.W3C(aromatic component)was positively correlated with Enterobacter.W6S(hydride)was positively correlated with Enterobacter,Ralstonia and Leuconostoc.W5C(short-chain alkane aromatic component)was positively correlated with Enterobacter.W1S(methyl group)was positively correlated with 18 genera,and W1W(sulfide)was positively correlated with Lactobacillus and Acinetobacter.W2S(alcohols,aldehyde ketone)was positively correlated with Enterobacter.W2W(organic sulfide)was positively correlated with Lactobacillus and Acinetobacter,and negatively correlated with Microbacterium.W3S(long-chain alkanes)was positively correlated with Enterobacter and Leuconostoc,and negatively correlated with Lactobacillus.Sourness,bitterness and astringency signals were positively correlated with Lactobacillus,and negatively correlated with Microbacterium.Umami,richness,saltiness,aftertaste-B signal values were negatively correlated with Lactobacillus,and positively correlated with Microbacterium.