Effects of processing on pigments of certain selected vegetables

The effects of thermal processing and the pH of the cooking media were investigated on pigments of beet roots, carrots, fenugreek and tomatoes. The pH had a substantial effect on betanins and chlorophyll and marginal effects on beta carotene and lycopene. Heat treatments affected some of the pigments, but between methods of heat ueatment, i.e., pressure cooking or steam cooking, variations were not generally encountered. Batch-to-batch variations were observed in certain pigments, which may be due to the level of maturily of the vegetable varieties and production variables. Sensory analysis of samples revealed a large variation in responses of panelists. There was a close correlation between instrumentally measured and visually analyzed color parameters; the largest effect was due to the cooking media treatment.