Study On The Dynamics Of Fungal Flora And Quality Of Wine During Fermentation In Linfen Production Area,Shanxi

This study took three dry red wines from the Linfen production area in Shanxi as the research object.Samples were taken in the early stage(day 1),middle stage(day 4),and later stage(day 8)of fermentation,high-throughput sequencing technology and traditional culture medium were used to explore the flora diversity and succession law of dry red wine in the Linfen production area of Shanxi.In addition,starting from the 0th day of fermentation,the fermentation broth was sampled every 24 hours to determine the changes in physical and chemical components during the fermentation process,providing a theoretical basis for the monitoring and optimization of the winemaking process and the introduction of wine grape varieties.In addition,three dry red wines of Cabernet Sauvignon,Marselan and Cabernet Franc,and three dry white wines of Chardonnay,Noble Fragrant,and Longan in the Linfen region of Shanxi were studied.Spectrophotometry and nuclear magnetic resonance technology were used to analyze Research on the antioxidant properties and metabolites of wine was carried out to compare the differences in the composition of different varieties of wine,and to provide a reference for scientific evaluation of the biological activity and taste and flavor of the wine in this region.The main findings are as follows:1.Diversity and dynamic changes of the fungal flora during the fermentation of dry red wine in the Linfen production area of Shanxi(1)The dry red wines in the Linfen production area of Shanxi have the highest fungal flora in the early stage of fermentation.The fungal composition of Cabernet Franc is relatively stable before,during and after fermentation.The fungal flora of Cabernet Sauvignon and Marselan changed drastically in the early stage of fermentation,and stabilized in the middle to late stage.(2)The dynamic changes of the fungal flora during the fermentation process are:in the early stage of fermentation,the main strains are Hanseniapora uvarum,Aureobasidium pullulans,Mortierella alpina,and Guehomyces pullulans,Saccharomyces cerevisiae,Rhodotorula sp,Candida tropicalis,Issatchenkia orientalis;among which H.uvarum occupies a dominant position,reaching more than 70%.In the middle of fermentation,Aspergillus niger,Rhodotorula mucilaginosa,and Rhodotorula diobovata appeared,but R.sp ceased to exist,and the proportion of S.cerevisiae rose to over 75%,occupying a dominant position,while H.uvarum fell to second place.Other strains have declined.In the late fermentation stage,Stachybotrys microspora appeared,and S.cerevisiae accounted for more than 90%,which had an absolute advantage.(3)The main yeast species in the fermentation process of dry red wine in the Linfen production area of Shanxi were detected using traditional culture media as H.uvarum,S.cerevisiae,C.tropicalis,I.orientalish and R.sp,which were consistent with the sequencing results,Once again verify the accuracy of the high-throughput sequencing method.2.Changes in physical and chemical components of dry red wine in the Linfen production area of Shanxi during the fermentation process(1)Different varieties affect the start time,rate and cycle of fermentation in wine.In natural fermentation mode,Cabernet Sauvignon starts fermentation on the first day,and the fermentation cycle is 11 days;Cabernet Franc starts fermentation on the second day,and the fermentation cycle is 8 days;Marselan starts fermentation on the third day,and the fermentation cycle is 10 days.(2)The changes in physical and chemical components of the dry red wines during the fermentation process are similar:the total sugar and soluble solids continue to decrease,the alcohol content and chroma continue to rise,the total acid first rises and then falls,the pH changes unstable but the pH at the end of fermentation is lower than the pH before fermentation.(3)The physical and chemical components of the new varieties of Marselan wine meet the requirements of dry wine:residual sugar content is below 4 g/L,total acid content and pH value are 6.10 g/L and 3.4 respectively.And the chromaticity value is higher,which has color advantages.It shows that the Marselan variety in the Linfen production area of Shanxi has the potential to make dry red wine and can be developed and utilized.(4)The physical and chemical components of wine are related to Hanseniaspora,Mortierella,Aureobasidium and Saccharomyces.Among them,the chromaticity has a strong correlation with Hanseniaspora and Saccharomyces.3.Antioxidant and metabolites of wine in the Linfen production area of Shanxi(1)There are differences in the content of phenolic substances among six kinds of wines in Linfen,Shanxi.Among them,Cabernet Sauvignon has the highest content of total phenols,total flavonoids,and total flavanols,reaching 1341.67 mg/L,872.08 mg/L and 536.67 mg/L,respectively.But Marselan wine has the highest total anthocyanin content,reaching 228.08 mg/L.(2)There are differences in the antioxidant capacity of six kinds of wines from the Linfen production area in Shanxi.Among them,Cabernet Sauvignon wine has the highest cupric reducing antioxidant power,DPPH scavenging capacity,and ABTS scavenging capacity,which are 12075 μmol/L,9079 μmol/L and 11898 μmol/L,respectively.(3)The composition of metabolites of different varieties of wine is the same,mainly including amino acids,organic acids,sugars,phenols,etc.However,there are differences in content:Cabernet Franc wines have higher levels of glycerol and succinic acid,Cabernet Sauvignon wines have higher levels of gallic acid,malic acid,and choline,Marselan wines have higher levels of proline,alanine,lactic acid,and ethyl acetate.Therefore,in this experiment,Cabernet Franc wine has a richer taste,Cabernet Sauvignon wine has stronger biological activity and healthy functions,and Marselan wine has a soft taste and richer aroma.