Determination of 18 Organic Acids in Rice Flavored Liquor Fermentation Broth by High Pressure Liquid Chromatography

In order to establish organic acid quality control method including short chain volatile fatty acids for Baijiu distillery, the quantitative method of 18 organic acids was developed by HPLC. Each organic acid was separated effectively by flow rate and gradient optimization. The final optimized analytical conditions were listed as follows: the column was Atlanis T3 column(4.6 mm×250 mm, 5 μm), flow rate was 0.4 mL/min, gradient elution was adopted, column temperature was 30 ℃, detection wavelength was 210 nm, and sample loading volume was 10 μL. This method had a wide linear range, R²>0.989, as well as quantitative limits were from 0.280 to 3.138 mg/L, recovery rates were from 93.03% to 107.21%, relative standard deviations were less than 3.70%. The results of tracking the changes of the contents of organic acids in the ferment broth of rice-flavored liquor during its fermentation process showed that the content of each organic acid showed different changing trends during fermentation. Comparing with those of initial fermented mash, the contents of all the organic acids except citric acid, L-malic acid, fumaric acid increased in the fermented mash of 12th day. L-lactic acid, acetic acid, isobutyric acid, isovaleric acid and succinic acid were the five most abundant organic acids in fermented mash of 12th day, the amounts of them were all more than 10% of total organic acid. In addition to the even increasing of the total organic acid amount, the distributions of organic acids in different stages of fermentation were significantly different. It was suggested that the composition of rice flavor organic acids could be effectively controlled by adjusting the fermentation duration. This method is an effective analysis method for the acidity quality control of rice-flavored liquor production.