Non-volatile Organic Acid Profiles of Peas and Carrots Cooked by Microwaves ¹

Frozen peas and frozen carrots were obtained from a local supermarket and cooked in a consumer microwave oven (550 watts of cooking power) and in an institutional microwave oven (1150 watts of cooking power). Non-volatile organic acids of each vegetable were identified and quantitated by gas-liquid chromatography. Lactic, succinic, malic and citric acids were identified in peas. Relative concentrations of these acids increased after cooking, particularly in samples cooked without water in a consumer microwave oven. Only malic acid was identified in carrots. Concentration of this acid was not affected by any cooking treatments used in the study. The non-volatile organic acids found in both peas and carrots were not correlated with the sensory scores for flavor of these vegetables. However, total non-volatile organic acids found in peas tended to be negatively correlated with the total chlorophyll retention of all the cooked pea samples.