Screening Of High-quality Fruit-flavored Indigenous Saccharomyces Cerevisiae

Current wine companies in China basically use commercial strains for fermentation to ensure the final quality of the wine,but this process can produce highly homogenized wines,reducing the complexity of the wine and losing the typical regional organoleptic characteristics.Preferential selection of indigenous Saccharomyces cerevisiae from grape origins is an effective means of protecting the typical flavors of wines produced in a given region.The selection and breeding of indigenous Saccharomyces cerevisiae in China is still in its infancy.In this study,based on the previous isolation,identification and screening work from the postdoc of Yantai Chang Yu Group,17 strains of indigenous Saccharomyces cerevisiae and the characteristic grape variety of Yantai appellation,Cabernet Gernischt,were used as research materials,and 6 strains of commercial brewer’s yeast were selected for comparative fermentation.The study investigated the applicability of indigenous Saccharomyces cerevisiae in the fermentation process based on the influence the aroma quality and sensory evaluation of wine,with the aim of screening indigenous Saccharomyces cerevisiae with strong fruity characteristics and laying the foundation for the commercialization of indigenous Saccharomyces cerevisiae.The main research results are as follows.(1)Primary sieving of fruity indigenous Saccharomyces cerevisiae: 17 strains of indigenous Saccharomyces cerevisiae: CY1,CY2,CY3,CY4,CY5,CY6,CY7,CY8,CY9,CY10,CY11,CY12,CY13,CY14,CY15,CY16,CY17 and two strains of commercial yeast: ES488 and RC212 were studied.The basic physicochemical indexes of the wine samples all conformed to GB/T 15037-2006;CY2 fermented wine samples had the highest total amount of aroma substances and CY9,CY6,CY2 and CY11 fermented wine samples had higher alcohol content,within the range of 147.59～325.84 mg/L;The content of esters in the fermented wine samples of CY2,CY6,CY4,CY1 and CY5 was high,within the range of 71.65～76.13 mg/L.The fruit aromas of the wines were mainly derived from the esters in the wines,such as ethyl acetate,ethyl butyrate,ethyl caprate,isoamyl acetate,ethyl caproate,which gave the wine samples a strong fruit aroma of peach,apple,pear,and strawberry.Principal component analysis was performed on the fruit aroma substances in the wines,and 18 characteristic fruit aroma substances were selected.The top 6 indigenous Saccharomyces cerevisiae were CY2,CY6,CY1,CY9,CY11 and CY4 after comprehensive sensory evaluation and principal component analysis of characteristic fruit aroma substances.(2)Rescreening of fruity indigenous Saccharomyces cerevisiae: Sensory evaluation,basic physicochemical indexes,and aroma substance analysis were conducted on wine samples fermented by 6 indigenous Saccharomyces cerevisiae and 4 commercial fruity yeast strains: FERMOL TROPICAL,SP,L.A,and XR.The results showed that the wine samples fermented by Saccharomyces cerevisiae CY2,CY6,CY1,and XR had higher ethanol ester content and showed strong fruit aroma characteristics.Sensory evaluation of wine samples fermented by indigenous Saccharomyces cerevisiae CY2,CY6 and CY1 had aroma characteristics of apple,pear,peach and strawberry,corresponded to the high content of ethyl butyrate,hexyl acetate,ethyl caproate,phenethyl acetate;wine samples fermented by CY9 and CY11 had aroma characteristics of cherry,citrus,lemon and banana;corresponded to the high content of isoamyl acetate,1-decanol.Combined with the analysis of the main components of the characteristic fruity aroma substances,we finally obtained that CY2,CY6 and CY1,the three strains of indigenous Saccharomyces cerevisiae fermented liquor had higher overall scores of fruity aroma.(3)Fruity indigenous Saccharomyces cerevisiae validation test: The sensory evaluation,basic physicochemical indexes and aroma substances of the fermented wine samples of the three indigenous Saccharomyces cerevisiae strains: CY2,CY6,and CY1 and the commercial fruity yeast SP validation test were studied.The total amount of esters,acetate esters and ethanol esters in the fermented wine samples of CY2,CY6 and CY1 were higher than those of the commercial fruity yeast SP.The sensory evaluation showed that the indigenous Saccharomyces cerevisiae after expanded production still had strong fruit flavor characteristics of apple,strawberry and peach.The basic physical and chemical indexes of the fermented wine samples,the content of fruity aroma characteristic substances,the sensory evaluation were integrated,and three indigenous Saccharomyces cerevisiae were selected from 17 indigenous Saccharomyces cerevisiae: CY2,CY6,and CY1.The wine samples fermented by these three indigenous Saccharomyces cerevisiae still had strong fruit aroma characteristics in the validation test,which laid the foundation for further commercialization of indigenous Saccharomyces cerevisiae.