Screening Of Fermentation Strains Of Kiwi Fruit Wine And Study On Quality Of The Wine Body

The lack of special fermented strains in the production of kiwi fruit wine and the wine prone to browning leads to the problems that lack of typicality,insufficient flavor and darkening of wine color.Thus,the purpose of this study was to screen yeasts with excellent fermented performance to enrich the composition of flavor compounds and improve the typicality of kiwi fruit wine,explore the main factors leading to the browning of kiwi fruit wine and find effective browning inhibitor to stabilize the color quality of the kiwi fruit wine,providing a theoretical basis for improving the quality of kiwi fruit wine.The main contents and results of this study were as follows:（1）The 2 native Saccharomyces cerevisiae with excellent fermentation performance were selected step by step from the natural fermentation broth of kiwi,the S.cerevisiae XX-16 was determined as the preferred strain for kiwi fruit wine brewing based on the physicochemical and sensory quality of kiwi fruit wine.Compared with the 3 control strains,the main fermentation time of XX-16 was reduced by 0.5 d,and the total phenolic content of kiwi fruit wine fermented by XX-16 was higher,at 740.51 mg GAE·L^-1;the strongest antioxidant activity in vitro with reducing power,ABTS⁺,and DPPH free radical scavenging activity of 635.75,603.21,and 743.35 mg VC·L^-1,respectively;the most abundant terpene of 22 species and the highest terpene content of 757.53μg·L^-1;the highest sensory score of 89.83 points.By combining the odor activity value and partial least squares regression analysis,it was indicated that XX-16 could improve the quality of wine body through enriching the aroma-active compounds of esters and terpenes in kiwi fruit wine.（2）The non-Saccharomyces N-12 with highβ-D-glucosidase enzyme activity and strong tolerance was screened out,which had the potential to enrich the volatile flavor compounds of kiwi fruit wine.N-12 was mixed with XX-16 to fermented kiwi fruit wine in different inoculation methods,the optimal inoculation method was XX-16 inoculated 48 h after N-12based on the physicochemical and sensory quality of kiwi fruit wine.Compared with XX-16pure breed fermented kiwi fruit wine（NX48）,the wine fermented with the optimal inoculation method had a richer flavor compound composition,with 15 new terpenes appeared,such as borneol,cineole and 1,4-cineole,the content of terpenes increased by 14.06-fold;the total content of esters and flavor compounds increased by 17.33%and 43.87%,respectively;the aroma was more abundant and pleasant with the sensory score increased by 13.00 points.Linalool,α-terpineol,eucalyptol,nonenol,borneol,isoborneol,myrcene,beta-damascenone and decanal were the key aroma compounds of NX48 kiwi fruit wine by combining the odor activity value and partial least squares discriminant analysis.（3）The potential application of different browning inhibitors in inhibiting the browning of kiwi fruit wine and the main factors leading to the browning of kiwi fruit wine was explored.It was determined that the browning of kiwi fruit wine mainly occurred during the storage by monitoring the browning degree,and the change value of browning degree during this stage was 10.53 times that of the main fermentation stage.The browning degree of kiwi fruit wine added with VC,GSH,EDTA and SO₂（added in the form of potassium metabisulfite）during storage was monitored,the results showed that only SO₂ could effectively inhibit the browning of kiwi fruit wine,the browning degree of kiwi fruit wine was the lowest when the addition amount of SO₂ was 150 mg·L^-1,and compared with the control,the change rate of browning degree at the end of storage was reduced by 14.53%.Correlation analysis showed that there was an extremely significant negative correlation between browning degree and total phenolic content,with a correlation coefficient of-0.830,which indicated that phenolic compounds were the main factors leading to the browning of kiwi fruit wine during storage.