Effects of Heat Treatment on the Glucosinolate Content of Brassicaceae Vegetables

Abstract

We investigated the effects of heat treatment on the glucosinolate (GSL) content of Brassicaceae vegetables. The results obtained were as follows:
1. Highest decrease in the GSL content of watercress and broccoli was recorded on subjecting to a temperature of 50-60°C.
2. Residual amounts of aliphatic GSLs were found to be approximately 80% in broccoli that was subjected to an internal temperature of 95°C. Residual amounts of indolyl GSLs ranged between 20% to 75% depending on the kind of indolyl GSL.
3. The remaining amounts of both aliphatic and indolyl GSLs in boiled broccoli decreased with an increase in the boiling time. The boiling water retained only limited amount of GSLs, that is, approximately 7% of the aliphatic GSLs and approximately 18-20% of indolyl GSLs.
4. When broccoli was boiled in different volumes of water, the difference in the ratios of residual GSLs were found to be negligible.
5. No loss in the amount of GSLs content of the vegetables was recorded after heating to an internal temperature of 95°C with steam, superheated steam, or vacuum cooking.