Abstract:According to the results of single factor experiments and response surface analysis of Box-Behnken experimental design principle, the factors that influence the extraction rate of the organic acids in grapes were optimized. The 3 factors were solid to liquid ratio, the volume fraction of ethanol and pH value. The results showed that the optimum extraction conditions for organic acids in grapes were as follows: the solid to liquid ratio was 1∶16(g/mL), the volume fraction of ethanol was 76.37% and the pH value was 11.87. Under this condition, the extraction mass fraction of organic acids in grapes was 216.907 μg/g. The absorption spectra of complexes that generated by citric acid, tartaric acid and malic acid with copper sulfate were overlapping seriously. So it's very difficult to separate each component with photometric method. In this paper, the partial least squares method was used for simultaneous determination of the simulation ofmixed citric acid, tartaric acid and malic acid complexes. And the method was also be used in the determination of organic acids in grapes. To the analog mixed sample the recovery rate was 99.6%~99.8%, and the RPEs was 0.64%~0.67%.
