Study on the Change Rules of Acids in Merlot Dry Red Grape Wine during Malolactic Fermentation

Malolactic fermentation(MLF) is an important approach to improve the quality of grape wine.For most red grape wine and some white grape wine,MLF was carried out to turn malic acid into lactic acid and carbon dioxide.In this paper,wine compositions during MLF in merlot dry red grape wine(made in Changli in 2007) were determined by wine ingredients rapid analyzer(WineScan FT120 type).The change rules of malic acid,lactic acid,total acids,pH value and volatile acids were analyzed.The results showed that it was easier to trigger MLF as pH value was high and SO2 content was low,and 80 % malic acid was degraded rapidly in the late stage of MLF.The coversion of malic acid to lactic acid might induce the decrease of total acids and the increase of pH value.Acid-reducing induced by malic acid decarboxylation accounted for more than 94 % of total acid-reducing quantity.pH value increased by 0.09～0.14 after MLF.And volatile acids content increased slightly to about 0.03～0.06 g/L.