Influence of cultivar and harvest time on the amounts of isoalliin and methiin in leek (Allium ampeloprasum var. porrum).

Extracts of 31 leek cultivars were analyzed using liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to determine the distribution of the two most abundant S-alk(en)yl-l-cysteine sulfoxides (ACSOs) in leek, that is, isoalliin and methiin. The isoalliin concentration of the white shaft and green leaves of the 31 leek cultivars varied from 15 to 53 mg/g dry weight (dw) and from 9 to 45 mg/g dw, respectively, whereas the methiin concentration varied from 3 to 16 mg/g dw and from 1 to 10 mg/g dw, respectively. Leek cultivar and tissue had an effect on the ACSO amounts.