| Gongniang No.1 is a cold-resistant wine grape variety hybridized from Vitis amurensis and Muscat de Hamburg in China.One of the outstanding problems of Gongniang No.1 is that it is almost impossible for making drinkable dry red wine throughout the biological deacidification by the malolactic fermentation because of the too high acidity and too low pH of its grapes.In this study,we used Gongniang No.1 brut wine(wine that just finish the alcoholic fermentation but not sulphited)from the Gaomi,Shandong Province and the brut wine with low acidity of Ecolly,Meili and Hutai No.8 from the Yangling,Shaanxi Province to blend in different proportions then perform the malolactic fermentation for decreasing the acidity to obtain high-quality Gongniang No.1 blend wine,and to provide the theoretical and practical basis for making wine with Gongniang No.1 and other high-acid grape varieties,and also the table varieties with low acidity as Hutai No.8.The main results are as follows.1.Gongniang No.1 in Gaomi,Shandong was harvested on August 22,2018.The total acid content of grapes was 9.47±0.04 g/L(calculated as tartaric acid),mainly tartaric and malic acid,with less oxalic acid,succinic acid,citric acid,and lactic acid.2.The total acid content of Gongniang No.1 brut wine was 9.93±0.28 g/L(calculated as tartaric acid),pH 3.17±0.02.The total acid content of Ecolly brut wine was 7.04±0.11 g/L(calculated as tartaric acid),pH 3.26±0.02.The total acid content of Meili brut wine was 6.5 8±0.13 g/L(calculated as tartaric acid),pH 3.57±0.02.The total acid content of Hutai No.8 brut wine was 4.66±0.10 g/L(calculated as tartaric acid),pH 3.85±0.04.The organic acids in the 4 brut wines were all composed of tartaric acid,malic acid,succinic acid,and oxalic acid,mainly tartaric acid,followed by malic acid.3.After the malolactic fermentation of the blend wines of Gongniang No.1 and Ecolly brut wine in different proportions(3:1=E1,1:1=E2,1:3=E3,v/v),the content of total acid,dry extract,total phenols,anthocyanins,flavonoids,and flavan-3-ols gradually decreased and the pH gradually increased as the proportion of Ecolly brut wine increased.Ten kinds of monomeric phenols were identified in all of the blend wines,and the content of monomeric phenols in E1 was the highest.E3 had the highest score in clarity,aroma quality,aroma intensity,taste intensity,and overall sensory evaluation.Therefore,the optimal blending ratio of Gongniang No.1 and Ecolly brut wine was 1:3(E3).4.After the malolactic fermentation of the blend wines of Gongniang No.1 and Meili brut wine in different proportions(3:1=M1,1:1=M2,1:3=M3,v/v),the content of total acid,dry extract,total phenols,anthocyanins,and flavonoids gradually decreased,and the pH and flavan-3-ols content gradually increased as the proportion of Meili brut wine increased.Eleven kinds of monomeric phenols were identified in all of the blend wines,and the content of monomeric phenols in M1 was the highest.M1 had the highest score in clarity,aroma quality,aroma intensity,taste intensity,and overall sensory evaluation.Therefore,the optimal blending ratio of Gongniang No.1 and Meili brut wine was 1:3(M3).5.After the malolactic fermentation of the blend wines of Gongniang No.1 and Hutai No.8 brut wine in different proportions(3:1=H1,1:1=H2,1:3=H3,v:v),the content of total acid,dry extract,anthocyanins,and flavonoids gradually decreased,and the pH and flavan-3-ols content gradually increased as the proportion of Hutai No.8 brut wine increased.Nine kinds of monomeric phenols were identified in all of the blend wines,and the content of monomeric phenols in H1 was the highest.H2 had the highest score in color,aroma intensity,body,and overall sensory evaluation.Therefore,the optimal blending ratio of Gongniang No.1 and Hutai No.8 brut wine was 1:1(H2).6.The malolactic fermentation reduced the content of total acidity,malic acid,tartaric acid,and succinic acid,increased the content of lactic acid,and changed the content and proportion of phenolic substances in blend brut wines,and so improved their sensory quality.7.The results of the comparative experiment of malolactic fermentation of the blend brut wines started by native lactic acid bacteria SD-2a and imported commercial lactic acid bacteria L450 showed that SD-2a had better malolactic fermentation performance,the wine fermented by SD-2a was scored higher on the sensory evaluation.In summary,the method of blending the brut wine of low acid content and the Gongniang No.1 can effectively start the malolactic fermentation,decrease the total acid and improve the quality of the blend wine,and E3 showed the best.Native lactic acid bacteria SD-2a were excellent strains for malolactic fermentation. |
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