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.