Vitamin C Content of Fresh and Prepared Vbgetables Assayed by 2, 4-Dinitrophenylhydrazine Colorimetric Method and HPLC

Abstract

We tried to clarify whether the total vitamin C (ascorbic acid plus dehydro-ascorbic acid) content in fresh, frozen and cooked vegetables from commercial sources measured depends on the method used for measurement. Total vitammin C content in fresh vegetables measured by the colorimetric method using 2, 4-dinitrophenylhydrazine was similar to that obtained by HPLC, and consistent with the values indicated in the standard table of Food Composition in Japan. However, total vitamin C content in frozen and cooked vegetables measured by HPLC was only 47.5 % of that measured by the colorimetric method. These data indicate that the actual value of vitamin C content in cooked vegetables is one third to one fifth that in fresh vegetables.