Preparation Of Yeast-lactic Acid Bacteria Co-fermented Low Alcohol Pear Wine

Fruit wines brewing has a long history such as prestigious wines,ciders and persimmon wines and so on.However,the development of fermentation technology for low-alcohol fruit wines that has risen in recent years is still at an initial stage.At present,strains used for fermenting fruit wines were often selected from wine yeasts.In order to achieve low alcohol requirements,physical alcohol removal or control of fermentation conditions is often used.The research on using non-Saccharomyces yeast to ferment low-alcohol wines is still at a preliminary stage.In this paper,lactic acid bacterias and yeasts isolated from fruit or fruit fermentation broth were selected as research objects.Pears were selected as the fermentation material arid non-Saccharomyces yeast and lactic acid bacterias suitable for fermenting low alcohol pears were selected for co-fermentation.The main research content as follows:(1)Fruits such as grapes,pears,apples,dragon fruit,bananas,papaya,kiwifruit,etc.were selected as research objects for yeasts and Lactic acid bacteria,identification results showed that 8 strains of non-Saccharomyces yeast and 6 strains of lactic acid bacteria,and the research on the sugar-,acid-and lactic acid-tolerance or alcohol-tolerance characteristics released that the strains with good tolerance were screened out,including Pichia kudriazvii KD-5,Clavisopora lusitaniae PT-3,Lactobacillus plantarum ZG-2 and Lactobacillus paracasei BG-1.(2)Using pear juice as the fermentation substrate,the selected strains as fermentation strains,and determined the fermentation performance during the process.The results showed that the growth of Clavisopora lusitaniae PT-3 in pear juice was better than that of the library.In Pichia kudriazevii KD-5,the ethanol production was 6.5%and 4.0%,respectively,in line with the requirements for low alcohols;KD-5 and PT-3 were different in the utilization of carbohydrates and production of organic acids,KD-5 has higher utilization of sucrose,and the fermentation broth by KD-5 contains more abundant organic acids than PT-3,but the total amount is lower;meanwhile the fermentation broth also contains the most abundant volatile components such as 17 kinds of esters,4 alcohols,1 ketones and so on.Lactobacillus plantarum ZG-2 produced significantly more lactic acid than L.paracasei BG-1,however,BG-1 could produce most abundent volatile components at 72 h of fermentation among all the broth fermented by lactic acid bacterias.(3)According to the study of the potential symbiosis between yeasts and Lactic acid bacterias,it was found that the mixed cultures of Pichia kudriazevii KD-5 and Lactobacillus paracasei BG-1 have mutual promotion,as a result,the two strains were acted as the starter for co-fermentation.The impact of three factors that including yeast inoculation(A),fermentation time(B)and initial sugar concentration(C)on sensory characteristics,ethanol content and residual sugar content was analyzed through the orthogonal test L9(34).The results showed that the best combination was 5%yeast inoculation,7 days fermentation period and 14%initial sugar concentration.Under this condition,the alcohol content was 2.35%,and the residual sugar amount was 43.0g/L,sensory score was 86 of the fermented low alcohol pear wine with delicate and tasty feature,moderate sweetness,rich ester and mellow body.In this paper,non-Saccharomyces yeasts and Lactic acid bacterias were isolated from spontaneous fermentation broth of fruits,and the fermentation performance of selected strains fermentation performance was compared,and mixed fermentation of low-alcoholic pear wine was enriched on the one hand.The microbial resources of the alcoholic fruit wine fermentation,on the other hand,provide the corresponding data basis for the development of low-alcohol fruit wine,which will facilitate the further development of low-alcohol wines with a promising future.