Study On Yeast Screening Of Kiwifruit Wine And Optimization Of Its Fermentation Conditions For Compound Barm

Kiwi fruit industry has become an emerging pillar industry in Neixiang County,Xixia County and other places in Nanyang,which with a planting area of about 200 thousand mu.However,due to the backward key technologies of preservation and processing,the planting income is low.Therefore,improving the quality of kiwi fruit wine can not only drive the development of kiwi fruit wine industry,but also increase the added value of products,promote the healthy development of kiwi fruit industry and help farmers increase their income.However,due to the influence of fermentation strains and technology,kiwi wine still has some urgent problems to be solved,such as weak flavor,weak fruit flavor and ester flavor.Using physical and chemical factors to mutate and improve yeast strains,and using non Saccharomyces cerevisiae to improve wine quality and enrich wine aroma have become research hotspots.Therefore,in order to solve the problems of insufficient aroma of Saccharomyces cerevisiae and poor tolerance of non Saccharomyces cerevisiae,mutation and protoplast fusion were used to improve the fermentation performance of the strains,and the optimization of kiwi fruit wine fermentation by compound barm was studied in this paper.The main research contents of this paper are as follows:1.Saccharomyces cerevisiae(SY)as a parent strain was treated by atmospheric and room temperature The results of the ARTP mutagenesis system were as follows:110W power,2 mm exposure distance and a mutagenesis time of 100s.Saccharomyces cerevisiae(SY)was mutagenized under these conditions,a mutant strain S2-15 that tolerated16%vol alcohol and p H 2.5 acid was obtained.The Kiwifruit wine is brewed,wine content is 12.17%vol and total acid is 10.63 g/L,the alcohol content increased by 12.9%and total acid decreased by 8.04%compared with the original strain,the residual sugar is low.It has obvious aroma with light floral and fruity aroma,and the mouth feel is better.The mutant strain S2-15 can be used to improve the winemaking process of kiwifruit wine.2.The Hanseniaspora vineae was subjected to atmospheric and room temperature plasma(ARTP)mutagenesis.The results showed that the mutant strain H5-4 was screened,that tolerated 10%vol alcohol and p H 2 acid was obtained,and the fermentation rate of kiwifruit wine was improved compared with that of H.vineae.The wine content of the wine after fermentation for 7 days was 9.83%vol,increased 30.2%,and the acidity was15.74 g/L.Decreased by 7.7%compared with that of H.vineae.And the fruit wine has a light aroma,with strong floral and fruity aromas.It is a non-Saccharomyces cerevisiae strain that can be used alone to brew low-alcohol and flavored Kiwifruit wine.3.In this study,Hanseniaspora vineae and Saccharomyces cerevisiae,mutant strains S2-15 and H5-4 were used as test strains and Kiwifruit was used as raw materials.On the basis of single factor test,orthogonal optimization test was carried out to determine the optimal fermentation process of Kiwifruit wine fermented by mixed bacteria.The optimum main fermentation process by the initial strain was determined as follows:H.vineae inoculation 36 h in advance;inoculation amount 4%;inoculation ratio of Saccharomyces cerevisiae to non-Saccharomyces cerevisiae 1:1.5(V:V);initial sugar content 25°Brix.After fermentation at 25?for 9 days,Kiwifruit wine with strong aroma,elegant flower and fruit aroma and mellow taste was obtained,and the alcohol degree was 13.83%vol.The optimum main fermentation process by the mutant strain was determined as follows:H.vineae inoculation 36 h in advance;inoculation amount 3%;inoculation ratio of Saccharomyces cerevisiae to non-Saccharomyces cerevisiae 1:2(V:V);initial sugar content24°Brix.After fermentation at 25?for 7 days,Kiwifruit wine with rich wine aroma,obvious flower and fruit aroma and rich wine body was obtained,and the alcohol degree was 14.43%vol,The total acid is 11.33%,which is 32.83%lower than the initial mixed bacteria fermentation fruit wine,and the total phenol and V_C content were increased by13.84%and 39.60%respectively,showing good fermentation characteristics.4.The mutant strains S2-15 and H5-4 were used as the parents,protoplast fusion technology was used to select acid-resistant and ethanol-tolerant kiwifruit wine brewing strains.First of all the protoplast preparation processes of Saccharomyces cerevisiae S2-15and non-Saccharomyces cerevisiae H5-4 were obtained by the ultrasonic-enzymatic hydrolysis composite method as follows:the enzymatic hydrolysis temperature was 30°C,the enzyme concentration was 8%and 3%,the ultrasonic time was 60 min,and the protoplast preparation rates were 60.17%and 76.48%.Secondly,the lethality of S.cerevisiae S2-15 and non-Saccharomyces cerevisiae H5-4 protoplasts reached 100%when heat-inactivated at 75°C for 420 s and UV-inactivated for 480s,and the fusion was induced by 35%PEG-6000 for 30 min.rate 7.5×10^-2.Then,12 acid-resistant and ethanol-resistant strains were screened by streaking and purifying the fusion strains with early growth and good growth and inserting into a Duchenne fermentation tube with an ethanol concentration of 16%and a p H value of 2.0.Finally,a high-tolerance and low-acidity aroma-producing strain R34,which can be used for kiwifruit wine brewing,was screened through comparative analysis of DNA content,fermentation capacity,physical and chemical indicators,and amino acid content.The kiwifruit wine brewed with this strain has an alcohol content of 11.71%vol,total acid content of 11.91 g/L,total phenolic content of827 mg/L,V_C content of 709.72 mg/L,total amino acid content of 14.77 mg/L,the sensory score of 84.33,the floral and fruity fragrance is elegant,and the sour taste is refreshing.