Emission of Blanched Broccoli Volatiles in Headspace During Cooking

Abstract

Broccoli florets CBrassica oleracea L.) were cut, blanched at 85�C far two minutes and frozen for the experiments. The emission of 14 volatile compounds was followed by headspace gas chromatography - mass spectrometry while cooking the material in water for 13 min at 95�C. After cooking in closed or open vessels the volatiles were swept with 120 mL He into a trapping column. Five traps were tested and a liquid phase with 100 % recovery was found COVI/ OV-25, II I). The percent coefficient of variance CV % of the major compounds typically varied between 3 and 30 %, including an internal variation of different broccoli samples from the same lot. The major volatiles in the headspace, measured with a flame ionization detector, were n-pentanal, 3-methyl-2-pentanone, n-hexanal, n-heptanal, cyclopentanecarboxaldehyde, ethyl acetate, 3-methylbutanal, 3-butenenitrile, 2-methylbutanal, dimethyl trisulfide and dimethyl disulfide indicating an efTective inactivation of enzymes, including myrosinase. The method has been applied to optimizing the processing of broccoli.