Screening And Process Optimization Of Key Fragrant And Excellent Strains In Msalais

The increasing market demand for Msalais has prompted the Msalais industry to transform from traditional workshops to large-scale craftsmanship.Under the premise of modern large-scale production,the unique flavor characteristics of traditional Msalais are preserved as much as possible.It is known that the key aromas of Msalais are jam aroma,dry aroma and caramel aroma,and its important contributing compounds are 2,5-Dimethyl-4-hydroxy-3-(2H)-furanone(DMHF),5-Methyl furfural(5-MF)and3-Methylsulfanylpropan-1-ol(3-MTP),which are mainly produced in the fermentation process.In this regard,this study combined the aroma thresholds of DMHF,5-MF and 3-MTP and their binary interactions,The yeast strains that have been screened and completed the winemaking characteristics,aroma production and related tolerance experiments are screened for high-yield key aromas.After optimization of fermentation conditions and laboratory test of Msalais,we hope to lay the foundation for the large-scale production of Msalais.The research shows that G2 has the best ability to produce key aroma,and the fermentation temperature is 28°C,the sugar content of concentrated grape juice is 27°Brix,the inoculation amount is 4%(v/v),and the ratio of skin residue:water is 96:1(g:L)It is the best process for G2 to produce aroma.The research conclusions are as follows:(1)The simulated wine with 12%alcohol content and the Msalais deodorant with 12%alcohol content are used as the base liquid,and the concentration of monomer fragrance 5-MF,DMHF and 3-MTP series are respectively prepared by 2-fold dilution method.The aroma threshold was determined by 3-AFC,and the aroma threshold was analyzed by the sigmoid curve.The results showed that the aroma thresholds of5-MF,DMHF and 3-MTP in simulated wine were 190?g/L,45?g/L and 382?g/L,respectively.The aroma thresholds of 5-MF,DMHF and 3-MTP in Msalais deodorant solution were 97.580?g/L,798.950?g/L and196.533?g/L,respectively.By studying the Brix of 7.4?7.9°Brix and 6.4?7.9°Brix of Msalais deodorant(12%ethanol)and the alcohol content of 8%,10%,12%,14%Msalais deodorant(The effect of sugar content(7.4?7.9°Brix)on the three aroma thresholds,a certain range of alcohol content and sugar content will not affect the threshold concentrations of 5-MF,DMHF and 3-MTP.The S-shaped curve and?-?diagram were used to study the interaction of the three key aroma binary mixtures in the two base solutions,and the binary mixture solutions with equal aroma intensity were all showing addition effects.Among them,the?-?diagram reflects the existence of low additive effect between aromas,and the S-shaped curve reflects the existence of synergistic effect between aromas.(2)Fermentation experiments were carried out on the F1,C1 and G2 that have been isolated and completed the winemaking characteristics,aroma production and related tolerance experiments.By studying its Growth curve,CO₂weight loss,soluble solids and wine-producing ability,it can be used as an important basis for judging fermentation characteristics.The results showed that there was no significant difference in biomass,hypoglycemic properties,CO₂release characteristics and alcohol production capacity among F1,C1 and G2,all of which met the basic fermentation requirements of Msalais.The ability of the strain to produce key aroma was determined,and it was found that the aroma content of DMHF and 5-MF in the fermentation broth of G2 was the highest,which were(54.055±1.924)mg/L and(13.310±0.825)mg/L,respectively.The aroma content of 3-MTP in the fermentation broth of F1 was the highest,which was(1354.072±91.508)mg/L.Through key aroma sensory analysis,combined with its threshold value and binary interaction in Msalais deodorant liquid,G2 were finally selected as the optimal Saccharomyces cerevisiae for follow-up research.(3)Single factor experiment and response surface design were used to explore the effects of fermentation temperature,inoculation amount,sugar content of concentrated grape juice and water content of skin residue on the aroma of caramel produced by G2.The verification experiment showed that:fermentation temperature of 28?,sugar concentration of concentrated grape juice 27°Brix,inoculation amount of 4%(v/v),skin residue:water ratio of 96:1(g:L)was the best process for G2 to produce aroma.(4)The Msalais pilot test was carried out according to the best technology.The soluble solid content of the brewed Msalais was(7.8±0.1)°Brix,the total sugar content was(46.12±1.420)g/L,the total acid content was(6.93±0.150)g/L,and the alcohol content was(13.428±0.730)%vol.The catechin content was(30.509±2.550)mg/L,the ferulic acid content was(0.432±0.030)mg/L,the resveratrol content was(0.934±0.007)mg/L,and the quercetin content was(0.431±0.034)mg/L.In addition,the contents of glutamic acid and?-aminobutyric acid were(0.052±0.009)mg/L and(0.017±0.006)mg/L,respectively.The content of 5-MF was(1.901±0.043)mg/L,the content of DMHF was(43.605±3.450)mg/L,and the content of 3-MTP was(1667.988±108.113)mg/L.50 kinds of volatile substances were detected by HS-SPME-GC-MS.Among them,there are mainly 15 kinds of esters,11 kinds of alcohols,9 kinds of acids,4 kinds of ketones,8 kinds of aldehydes,and 1 kind of sulfur-containing compounds.Sensory analysis showed that the wine had a strong caramel aroma.