Determination of 4 organic acids in yogurt by high-performance liquid chromatography

The research is to determine the organic acids in yogurt by high-performance liquid chromatography(HPLC),evaluate the flavor of yogurt by sensory evaluation,and compare the performances of 3 cultures.Three kinds of direct-vat-set cultures were used to produce yogurt respectively in a semi-industrialized way,and then the acidities of yogurt during fermentation were determined.Sensory evaluation was made to assess the quality of yogurt,and 4 kinds of organic acids(lactic,citric,pyruvic and formic acids) in yogurts were determined by HPLC.Results: It showed that all 3 cultures had quick acidity production,and all yogurts were proved to hold high qualities.The culture M and the self-made culture showed a weak post acidification while N culture showed strong.Some differences of the organic acids contents among 3 kinds of yogurt were observed.4 organic acids(lactic,citric,pyruvic and formic acids) in yogurt were determined effectively by HPLC,and the performances of 3 cultures were evaluated successfully in this experiment.