Investigation Of The Correlation Between Microbial Community Structure And Aroma During The Spontaneous Fermentation Of Ice Wine Made From Vidal Grapes

The wine region of Yili is an important wine producing region in the Xinjiang Uygur Autonomous Region,because of its special geographical location and climatic conditions.Ice wine is known as “liquid gold” for its fragrant smell,mellow taste,unique flavor and high price.However,the structure of microorganism during the fermentation of ice wine and its influence on the aroma is still unclear.It not only enriches the theoretical basis of wine microbes and flavor,but also enhances our understanding of the fermentation mechanism of ice wine by analyzing the correlation between microorganisms and aroma during the fermentation of ice wine.This study used spontaneous fermentation to ferment the Vidal grapes from the Yili into ice wine.Samples were selected in 6 time point of natural fermentation.Analysis of sample microbial structure by using High-throughput sequencing technology.Analysis of aroma in samples by Headspace Solid-Phase Microextraction-Gas Chromatography-Mass Spectrometry(HS-SPME-GC-MS).Finally,the correlation analysis between microbial structure and aroma in the natural fermentation process of ice wine was carried out.The research results are as follows:For bacterium,1337 OTUs were clustered,belonging to 26 phylum such as Proteobacteria,Firmicutes and Cyanobacteria et al.The top 10 bacteria in the relative abundance are Bacteroides,Sphingobium,Macrococcus,Pseudomonas,Sphingomonas,Massilia,Lachnospiraceae NK4A136 group,Pedobacter,Alistipes,Lautropia.For fungi,875 OTUs were clustered,belonging to 10 phylum such as Basidiomycota,Ascomycota et al.The top 10 fungi in the relative abundance are Vishniacozyma,Hanseniaspora,Cladosporium,Wickerhamomyces,Aureobasidium,Alternaria,Udeniomyces,Cystofilobasidium,Botrytis,Penicillium.Through the α diversity analysis and β diversity analysis,it was found that the structure of microorganism has undergone succession during the fermentation of ice wine.The aroma components and changes in the natural fermentation process of Icewine were studied.A total of 69 volatile substances were detected,including 13 alcohols,8 acids,22 esters,6 aldehydes and ketones,and 3 furans,2 terpene,7 hydrocarbons,4 phenols.Among them,the relative content of alcohols is the largest,accounting for 40%-50% of the total volatile components.Followed by esters,accounting for 20%-30% of the total volatile components.The relative content of alcohols increased gradually during the fermentation process.The acids first increased and then decreased during the fermentation process.The trend of esters was not obvious.The relative content of aldehydes,furans,oximes,phenols and hydrocarbons is low.The correlation between microorganisms and aroma was studied by spearmen and CCA correlation analysis methods.The results show that bacteria and acid substances have a strong correlation,fungi and ester substances have a strong correlation.Through O2 PLS analysis,8 bacterial genera and 9 fungal genera and 21 aroma components established 208 correlations.In bacterium,Sphingobium has the highest correlation with aroma components and is associated with 17 aroma substances.in fungi,Candida has the highest correlation with aroma and is associated with 20 aroma substances.