The Changes Of Malic Acid And Lactic Acid In Wine Brewing Process

the wine can only be made of broken or undamaged fresh grapes or grape juice that completely or partially ferment. Each organic acid of wine all has its own special flavor. The content of malic acid is very high. The usual method to detect the malic acid in wine is HPLC,and there is still a high accuracy detection methods with lower cost. But in recent years, a number of small wineries usually cannot afford to buy liquid chromatograpH, so a low-cost alternative method is needed to detect the malic acid.This thesis establishes a new method for malic acid detection in wine, and the method is with high accuracy, fast detecting speed, high recovery rate and low cost. Law measured by colorimetry malic acid and lactic acid content of the relationship, and the lactic acid content was calculated by malic acid content, through the analysis of the data obtained, malic acid-lactic acid between the standard regression equation: y₁ = 119.674x-0.269 y₂-35.332, a correlation coefficient of 0.985, the average recovery was 101%, the relative standard deviation RSD = 0.678%, a description of this method is accurate and reliable. Determination wine fermentation process malate Another use HPLC, HPLC and colorimetric determination method malic acid content were consistent, indicating that the assay can be used as a low-cost method for the determination of the place of malic acid in wine content.This thesis determines the detected method of lactic acid, yeast dry weight, reducing sugar and alcoholic strength,mainly using colorimetric method, and its relative deviation is less than 1%. In addition, the interfere of other components in grape juice can be ignored, the absorbance values can be detected by concentration gradient, then the concentration gradient can be obtained by drawing its standard curve.By comparing the parameters changes and differences in grape juice fermentation process, we can find that malic acid content will increase with the fermentation, when the fermentation is over, malic acid content will gradually decrease and stabilize finally because of the reaction between malic acid and lactic acid.Fermentation parameters were determined by the respective content of malic acid under different sugar content, different temperature conditions and different grape varieties- lactatereaction known temperature malolactic reactions are obvious direct impact, indirect impact significantly reducing sugars alcohol content of 12% cut-off point of malic acid- lactic acid fermentation significantly affected.