Isolation,Identification And Application Of Flavor Bacteria M5 Based On Flavor-Oriented

In order to tap the local high-quality strain resources,improve the quality of traditional liquor and vinegar products in Shanxi.In this paper,the fragrant bacteria were extracted and scented from the fragrant white liquor cellar by scenting technology combined with HS-SPME-GC-MS technology,and a strain M5 was obtained which could produce pleasant fruit fragrance,and tested the flavor substances to determine the best.The scented medium was identified by morphological,physiological and biochemical tests and 26 S r DNA sequence phylogenetic analysis,also researched on the growth,ester production ability and tolerance of the strain.Based on the main influence factors screened by single factor and PB test,the Box-Benhnken design was used to establish a mathematical model for response surface test.The optimal fermentation conditions for the ester production of the strain were determined and applied to the production of liquor and vinegar.The test results were as follows:(1)The best aroma culture medium for the production of fragrant bacteria analized by HS-SPME-GC-MS was sorghum solid medium,which had the best aroma,could produce fresh fruit flavor and contains milk flavor.The relative content of ?-phenylethyl alcohol in rose scent accounts for 28.14% of the flavor substance,and the ester content was as high as 26.5g/L.The strain,which confirmed by the morphological,physiological and biochemical tests and 26 S r DNA sequence phylogenetic analysis,belonged to the Geotrichum candidum of the genus Geotrichum,named as Geotrichum candidum M5.Through the study of the tolerance of the strain,it was found that the optimum growth temperature was 25°C,the sugar content was 10%,and the p H was 4.(2)Through the single factor,PB screening and response surface test,the optimal fermentation process parameters for the production of esters from G.candidum M5 were as follows:inoculum age 24 h,shaker speed 150r/min,inoculum size 11%,total ester content It reached 3.1301±0.0047g/100 m L,which was increased by 56% compared with the total ester content of the raw material.(3)The total ester and alcohol yield of the liquor were both increased,and extremely significant at the 1% level by strengthening alcoholic fermentation with G.candidum M5 and strengthening alcohol fermentation with Daqu.The highest total ester content of pre-mixed bacteria was 3.68±0.01g/L.Quantitative analysis by SPME-GC-MS showed that the aroma components of the liquor were enhanced and the ethyl acetate content was higher than the blank.Twice the control,making the aroma more harmonious.The fermented vinegar was enhanced by the G.candidum M5.Compared with the Daqu fermentation alone,the total acid and total ester content in the vinegar sample were significantly increased,which was extremely significant at the 1% level.Before the saccharification,the total acid and total ester content were increased by 21.52% and 28.22% respectively.The aroma components of each vinegar were analyzed by HS-GC-MS,and the relative content of acetic acid was obviously increased after the strengthening,acid,Esters,aldehydes,etc.are all tested with new ingredients.Considering the addition,the vinegar aroma is the most abundant in the addition of G.candidum M5 before saccharification.