Study On Change Law Of Microorganisms And Metabolites During Fermentation Process Of Lycium Ruthenicum Murr.Jiaosu

Lycium Ruthenicum Murr.jiaosu is rich in various nutrients and active substances,which has broad prospect of market.In this study,using Lycium Ruthenicum Murr.as main raw materials,Lycium barbarum L.,Potentilla anserina L.,Lepidium meyenii Walp,powder of Hippophae rhamnoides L,etc.as auxiliary materials,Lycium Ruthenicum Murr.jiaosu was prepared.The change laws of metabolites and antioxidant activities,types of dominant microorganism and diversities of microbial community were studied during the natural fermentation process.The antioxidant activity in vitro was also studied.At the same time,the fermentation and preparation conditions of the active Lycium Ruthenicum Murr.jiaosu were explored.The main results are as follows.1.From 0th to 30 th day during fermentation of Lycium Ruthenicum Murr.single jiaosu(LS),changes of microbial growth were more complex and showed an overall upward trend,which gradually decreased after 35 th day.From 0th to 10 th day during fermentation of Lycium Ruthenicum Murr.complex jiaosu(LC),changes of microbial growth showed an upward trend,which gradually decreased after 15 th day.Titratable acid in both LS and LC increased during fermentation.The content of total sugar decreased in early stage and stabilized in later stage,and a similar trend for reducing sugar.For anthocyanin,it showed fluctuated change in LS,while it gradually decreased in LC.The content of total flavonoids increased during fermentation in both LS and LC,and the content of total phenols was similar to that of total flavones.The content of total protein increased first and then decreased in early stage,and tended to be stable in later stage for both samples.Activity of SOD showed the same trend with the content of total protein in both samples.Activity of amylase showed a slow upward trend in LS,while no significant change in LC.Eleven kinds of organic acids were detected and majority were lactic acid,ascorbic acid and ?-aminobutyric acid during fermentation of LS.Thirteen kinds of organic acids were detected and majority were lactic acid,ascorbic acid,acetic acid,?-aminobutyric acid,oxalic acid,succinic acid and malic acid during fermentation of LC.Changes of DPPH free radical scavenging ability for two jiaosu were similar,which generally increased during early stage and then tended to be stable.Reducing power showed a slight increase in LS,which was different from that in LC.2.Three kinds of yeasts(Candida boidinii,Hanseniaspora opuntiae,and Pichia kudriavzevii),one mold(Penicillium corylophilum)and three kinds of lactobacillus(Lactobacillus paralimentarius,Lactobacillus plantarum and Enterococcus faecium)were isolated from LS.One yeast(Pichia kudriavzevii),one mold(Penicillium corylophilum)and two kinds of lactobacillus(Lactobacillus paralimentarius and Lactobacillus plantarum)were isolated from LC.3.Based on high throughput sequencing technology,the dynamic succession of microorganisms in natural fermentation of Lycium Ruthenicum Murr.jiaosu was studied.The results showed that the diversity and abundance of bacterial community were relatively high from 0th to 20 th day during fermentation.The diversity and abundance of fungal communities were relatively high from 30 th to 50 th day during fermentation.Before fermentation,the main bacteria were Pantoea,while the fungi were complicated and unclassified.Alternaria was a large part of the known fungi.During natural fermentation process,main dominant bacteria were Lactobacillus,and dominant fungi were Ascomycota and Basidiomycota.After 60 th day of fermentation,the main bacteria were Lactobacillus,and the main fungi were Saccharomyces.4.Main components and antioxidant activity in vitro of Lycium Ruthenicum Murr.jiaosu with different raw material ratio were analyzed and compared.The results showed that contents of titratable acids,total flavonoids,total phenols and activities of SOD were all increased after 90 th day of fermentation for single jiaosu(XD)and complex jiaosu(XF)including fresh fruits of Lycium Ruthenicum Murr.and single jiaosu(GD)and complex jiaosu(GF)including dried fruits of Lycium Ruthenicum Murr.Contents of total sugar,reducing sugar,the p H values,total protein and anthocyanin were decreased.The amylase activities in XD,GD and XF were increased,while that in GF was decreased.Total organic acids amounts in XD,GD and GF were increased,while that in XF was decreased.There were 12,13,12,and 12 kinds of organic acids in XD,GD,XF,and GF after fermentation,mainly lactic acid,succinic acid and acetic acid.Moreover,the DPPH free radical scavenging ability,total antioxidant capacity,hydroxyl free radical scavenging capacity and reducing power of four jiaosu all showed dose-dependent effects.The EC50 of DPPH free radical scavenging ability,hydroxyl free radical scavenging ability and reducing power were 0.049,0.017 and 0.071 mg VC/m L,respectively.Among them,GD showed relatively strong antioxidant activity.5.Through single-factor experiment and orthogonal design,processing technology of Lycium Ruthenicum Murr.jiaosu were studied.Optimal fermentation conditions were that the strain ratio(Pichia kudriavzevii : combined lactobacillus)was 2:3,the inoculation amount was 4%,the fermentation time was 2 d,and the fermentation temperature was 34 ?.Under these conditions,activity of SOD was 802.99±13.18 U/m L,and titrable acid content was 18.80±0.76 g/kg.Centrifugation speed of 7000 r/min(centrifugal force of 3380 g)and centrifugation time of 15 min were selected as centrifugation conditions for production of jiaosu.The optimal dry conditions for bacterial sludge were that additive amount of skimmed milk powder was 8 g/100 m L,trehalose was 3 g/100 m L,?-cyclodextrin was 0.2 g/100 m L,and the ratio of bacterial sludge and protective agent was 1:10.Under these conditions,the number of viable lactobacillus was 2.24×109 CFU/g,and the survival rate of lactobacillus was 86.15%.