Products of the hydrolysis of rapeseed glucosinolates

A study was conducted to identify the products, mainly nitriles and goitrin, of enzymatic hydrolysis of glucosinolates present in meals of a number of rapeseed varieties. The pH of autolysates of meals from seeds of the Cruciferae family ranged from 5.00 to 5.72. High glucosinolate varieties had lower pH than low glucosinolate varieties. On autolysis of law meals, the main hydrolysis products were nitriles with maximum production occurring at about pH 5 to 6. The most stable nitrile when hydrolysis conditions were changed was 1-cyano-2-hydroxy-3-butene. The presence of the nitriles 1-cyano-3,4-epithiobutane and 1-cyano-4,5-epithiopentane in rapeseed meal hydrolysates was confirmed by gas chromatography, infra-red spectrometry, nuclear magnetic resonance and mass spectrometry. Both nitriles were found in Candle, Torch, Regent, Midas and Tower rapeseed meals. Goitrin was the predominant product from heat-treated meal regardless of source of myrosinase enzyme.