Study On Mixed Strain Fermentation Of Lonicera Japonica Thumb And Characteristics Of Fermentation Broth

Honeysuckle is the dried flower bud of Lonicera japonica in the honeysuckle family.It has the physiological functions of antipyretic,anti-inflammatory,antibacterial,anti-virus,immune regulation,lipidlowering and antioxidant.It is a typical drug and food homologous plant and has important food development value.Based on mass spectrometry,this study studied the effects of mixed strain fermentation on the antioxidant performance,functional components and volatile substances of honeysuckle extract,hoping to provide reference and theoretical basis for the development of functional honeysuckle fermented beverage.The main research contents are as follows:(1)The raw materials of honeysuckle were screened by ion trap mass spectrometry.Taking the peak intensity of Chlorogenic acid mass spectrometry as the index,honeysuckle with high Chlorogenic acid content was selected as the experimental material.Using Lactobacillus plantarum and Saccharomyces cerevisiae as fermentation strains,3% honeysuckle aqueous extract as culture medium and polyphenol content as detection index,the effect of mixed fermentation on honeysuckle extract was studied in shake flask.The fermentation process was optimized by selecting fermentation temperature,fermentation time,inoculation and the proportion of Lactobacillus plantarum and Saccharomyces cerevisiae.The optimized conditions were as follows: fermentation time 72 h,inoculation amount 4%,ratio of Lactobacillus plantarum to Saccharomyces cerevisiae 1:3,fermentation temperature 37℃,glucose addition 2%.After optimization,the polyphenol content increased from 59.15 mg/g to 73.53 mg/g,with an increase rate of 24.3%,the free radical scavenging rate of DPPH(1,1-diphenyl-2-picrylhydrazyl)increased from 55% to 71%,and the free radical scavenging rate of ABTS 2,2’-Azinobis-(3-ethylbenzthiazoline-6-sulphonate)increased from 57% to64%.Further experiments were carried out in a 5L fermentor.After fermentation,the polyphenol content was increased from 49 mg/g to 61.5 mg/g,with an increase rate of 25.5%,the DPPH radical scavenging rate was increased from 48% to 56%,and the ABTS radical scavenging rate was increased from 75% to 85%.(2)In order to study the reasons for the changes of antioxidant properties of fermentation broth,the components of fermentation broth were qualitatively detected by liquid chromatography-mass spectrometry.The results showed that there were great differences between mixed fermentation and single strain fermentation.A total of 117 components were detected in the four extracts,39 specific components were detected in mixed fermentation,32 in lactic acid fermentation,24 in yeast fermentation and 25 in the control.Among the unique components of mixed bacteria fermentation,3-dehydro shikimic acid,5-o-ferulic quinic acid,cinnamic acid,dihydrocaffeic acid,bisphenol glucuronic acid,gallic acid,kaempferol,quercetin,3-galactoside and other substances are unique substances in the phenylpropanoid cycle.Mixed bacteria fermentation can promote the phenylpropanoid cycle.The content of chlorogenic acid and Luteolin in the fermentation broth increased from 35.236 mg/g to 43.279 mg/g by 18.58%.The results of correlation analysis showed that the improvement of antioxidant performance was highly correlated with the content of polyphenols,and strongly correlated with the content of Chlorogenic acid,Luteolin and Luteoloside.(3)The changes of volatile substances in fermentation broth were detected by GC-MS.33 effective peaks were detected in the control group and 49 effective peaks were detected in the fermentation group,including esters,alcohols and phenols.Among them,esters are mainly methyl esters and ethyl esters,such as methyl formate,methyl tridecanoate,methyl octadecadienylate,3,5-dimethyl benzoate and ethyl linoleate.In addition,there are some phenolic esters and alkenyl esters,such as hydroquinone acetate and tetradecyl acetate;Alcohols are mainly ethanol and its corresponding compounds,such as phenylethanol;Phenols include catechol(catechol),resorcinol and its derivatives,such as ethyl catechol.In the control group,pentafluorouracil and xylopyranoside accounted for about 26%;The contents of propoxyphenol,hydroxyphenylethanol,phenylethanol and catechol in the fermentation group were higher,accounting for about 46%.The types and contents of alcohols and organic acids changed greatly,which could change the odor of the fermentation broth to a great extent and increase the flavor of the extract.