ASCORBIC ACID AND COLOR CHANGES IN SUMMER SQUASH AS INFLUENCED BY BLANCH, pH AND OTHER TREATMENTS

Abstract

SUMMARYThe effect of time of blanch, pH, and other treatments on changes in ascorbic acid and color of summer squash puree was studied at 50°C to determine some of the chemical reactions that influence quality. Three types of changes occurred during holding at 50°C: (1) loss of yellow color; (2) browning reactions; and (3) loss of ascorbic acid. Ascorbic and dehydroascorbic acids were rapidly oxidized at 50°C. The reaction was slower at pH 5.0 than at pH 6.0 and 7.5. Color retention as measured by the CDM was greater at the higher pH levels. Time of blanch did not affect CDM a/b (hue) but did increase (chroma) and decreased the CDM L (lightness). Both color and ascorbic acid were lost very rapidly in unblanched squash puree under these conditions. Browning reactions had a major influence on CDM color values, even in blanched squash although the changes in carotenoid pigments were less pronounced.