EFFECT OF BLANCHING TREATMENTS ON THE FIRMNESS OF CARROTS

Abstract

ABSTRACT Carrots (26 varieties) were subjected to two blanching‐in‐water treatments prior to being canned in the conventional manner. (1) 4‐5 min blanch at 212°F, (2) 20–30 min blanch at 165°F. All of the low temperature blanch carrots were firmer than the corresponding high temperature treatment. Blanching was carried out at 130°, 150°, 170°, 190°, 212° F. The firmness, free methanol and pH of these treatments all showed the same trend, increasing as blanch temperature was raised from 130® to 170®F and decreasing as blanch temperature was raised from 170® to 212®F. This evidence supports the conclusion that the increase in firmness is caused by the effects of pectin methyl esterase PME) which is activated by the low temperature blanch and inactivated by the high temperature blanch.