Comparison Of Yeast Diversity And Aroma Analysis In Naturally Fermented Cabernet Sauvignon Wine Under Different Planting Modes

Yeast is one of the factors that have the greatest impact on wine quality during the brewing process.Commercial yeast is widely used in domestic wineries,and research on the application of local yeast strains that can represent the characteristics of the production area is still ongoing.Organic and biodynamic planting methods are new agricultural models that fully utilize the natural fermentation of local yeast,which can produce more complex aromas and produce wines with distinctive regional flavors.In order to promote the promotion of organic planting and biodynamic planting methods in production areas and increase attention to local yeast strains,this study used’Cabernet Sauvignon’ grapes from Yinchuan production area in the Eastern Foot of Helan Mountain in Ningxia as raw materials.Four groups were set up for natural fermentation treatment,including organic planting group,organic planting control group,biodynamic planting group,and biodynamic planting control group.The grapes were crushed on the 0th day and 2nd day,Samples were taken from the fourth day,sixth day,and eighth day.Study the differences in yeast community structure during natural fermentation under different planting modes;Exploring the impact of natural fermentation on the main aroma substances under different planting modes,providing theoretical basis for the promotion of organic planting and biodynamic planting methods in production areas,and enhancing the importance of local yeast specialization in production areas.The main research findings are as follows:(1)Isolation and identification of naturally fermented Cabernet Sauvignon wine yeast under different planting modes resulted in 1075 strains of yeast.Through WL morphological identification,16 different types of yeast were identified,and representative strains were selected from different types of yeast at different stages for identification.The 26S rDNA D1/D2 region sequencing identified that the tested strains were 8 genera and 9 species,respectively,Hanseniaspora.uvarum,Candida zemplinina,Zygosaccharomyces bailii,Metschnikowia pulcherima,Metschnikowia fricicola,Saccharomyces cerevisiae,Cryptococcus saitoi,Pichia.kudriavzevii,and Kazachstania bulgari.The results showed that there were differences in the species and proportion of yeast in different cultivation modes during different periods of natural fermentation.In the 0th day,non-Saccharomyces cerevisiae was the main type of yeast in different cultivation modes;In the 2nd day,the organic planting group was mainly composed of S cerevisiae,with half of the organic planting control group consisting of S cerevisiae and non-S cerevisiae.The biodynamic planting group and the biodynamic planting control group were mainly composed of non-S cerevisiae;In the fourth day,different planting modes all entered a period dominated by S cerevisiae;The sixth day and the eighth day are the dominant periods when the proportion of S cerevisiae is over 90%.(2)The high-throughput sequencing technology was used to analyze the microbial community structure of Cabernet Sauvignon wine samples under different planting patterns in Yinchuan production area at the Eastern Foot of Helan Mountain in Ningxia;The most abundant fungal genera in Cabernet Sauvignon grape samples under different planting modes are Cladosporium,Sporulated Hanson Saccharomyces,Alternaria,Powdery Mildew,and Botrytis;At the level of bacterial genera,the dominant genera are lactic acid bacteria,Fructobacilli,unidentified Chloroplast,unidentified Mitochondria,and pan bacterial genera.(3)The aroma components of naturally fermented Cabernet Sauvignon wine under different planting modes were determined using headspace solid-phase microextraction technology combined with gas chromatography-mass spectrometry.The results showed that a total of 40 volatile aroma compounds were identified in naturally fermented Cabernet Sauvignon wine under different planting modes,including 13 esters,20 alcohols,4 acids,and 3 other compounds.The main volatile compounds were alcohols,followed by esters and acids.The differences in aroma types are relatively small,but there are significant differences in some different aroma contents.The higher content of higher alcohols in different fermentation groups was found in the biodynamic planting group;The overall content of aroma substances in the organic planting group wine is relatively low;The organic planting control group wine has the characteristics of high ester content and low alcohol content;The overall aroma profile characteristics of wines grown under different planting modes are relatively similar,but there are differences in the intensity of aroma characteristics.The intensity of berry,tropical fruit,temperate fruit,floral,citrus,herbaceous,and spicy flavors in the biodynamic planting group wine is higher than that in other planting modes wine;The dry fruit and floral aroma intensity in the organic planting group wine was higher than that in the organic planting control group and biodynamic control group wine.In summary,the biodynamic planting group had a high concentration and significant complexity of wine aroma.The biodynamic planting group increased the proportion of higher alcohols in wine aroma,while the proportion of esters significantly decreased;The significant enhancement of floral,tropical,and temperate fruit flavors provides a theoretical basis for the production of high-quality wines with local characteristics,as well as the promotion of organic and bio dynamic planting methods.