Color changes of tomato purees during storage at freezing temperatures

The changes in color of unblanched and blanched tomato purees during storage at -7 and -18 degreesC were studied. They showed the typical sigmoidal-shape of radical reactions and were well described by the Logistic equation (R > 0.95; P < 101). After an initial induction time, a progressive increase in the bleaching rate was found for both unblanched and blanched frozen tomato purees. The color changes for the unblanched sample were statistically higher than those for the heated one. In the former case, the bleaching of carotenoids was attributed to both chemical and enzyme-catalyzed oxidation reactions. The effect of storage temperatures on color changes was appreciable only in the case of the unblanched tomato samples.