Simultaneous Determination of 13 Organic Acids during the Fermentation of Luocheng Vitis quinnquangularis Rehd by Kombucha Consortium

In order to get a feasible means to simultaneous detect organic acids in the fermentation process of kombucha bacteria, the method of accurate quantitation 11 organic acids and 2 relative quantitation in kombucha bacteria was established via liquid chromatography, and the changes of the organic acids in the fermentative kombucha broth of Luocheng Vitis quinnquangularis Rehd were also tracked. The analytical conditions of organic acids were optimized using the Atlanis T3 chromatographic column as follows:The mobile phase was 0.02 mol/L KH₂PO₄ (pH=2.6) with a constant flow rate of 0.4 mL/min.The column temperature and UV detection wavelength were set as 30℃ and 210 nm, respectively. Glucuronic acid and oxalic acid were completely merged into a co-elution peak, and the coelution peak was relatively quantified by standard curve of glucuronic acid. Meanwhile, the other 11 organic acids including gluconic acid and quinic acid were effectively separated in the fermentative kombucha broth of Luocheng Vitis quinnquangularis Rehd. The method has wide linear with correlation coefficients were all above 0.990. The quantitative limits were in the range of 0.080~4.789 mg/L, while he spiked recoveries ranged from 92.68%~107.35% with RSDs less than 5%. The fermentation process of Luocheng Vitis quinnquangularis Rehd was tracked and the synergistic evolution of organic acids was investigated. The contents of gluconic acid, acetic acid and malic acid keep on increasing during the fermentation process, while the changes of other acids turn to rise first and then fall later. Gluconic acid and acetic acid were the main organic acids, accounting for 75.03% and 10.46% of the measured organic acids in the fermentation broth of 17 d, respectively. This method is suitable to be applied to simultaneously determine the main organic acids in the fermentation broth of kombucha. The traced data during fermentation provide basic data for further development of acidic functional soft beverage from Luocheng Vitis quinnquangularis Rehd fermented by Kombuch consortium.