Total and Individual Glucosinolate Content in 11 Broccoli Cultivars Grown in Early and Late Seasons

Abstract

Broccoli (Brassica oleracea L. Italica Group) is an economically important vegetable crop and its consumption may benefit human health. Glucosinolates, a group of secondary plant metabolites found generally in the cultivated Brassicaceae, may protect against the development of certain malignancies. The objective of this study was to evaluate total and individual glucosinolate content of broccoli cultivars widely grown in southern Europe following spring vs. summer planting (early vs. late crop, respectively). Glucosinolates in primary and secondary inflorescences taken from mature plants were analyzed separately by high performance liquid chromatography (HPLC). The cultivars contained primarily 4-methylsulfinylbutyl-, indol-3-ylmethyl- and 1-methoxyindol-3-ylmethyl-glucosinolates. Total and individual glucosinolate levels varied significantly between seasons, among cultivars and between inflorescences. `Shogun' contained the highest total glucosinolate levels (between 35.2 mmol·kg-1 dry weight in primary inflorescences of the early crop and 47.9 in secondary inflorescences of the late crop). Total and individual glucosinolate levels were generally higher in the late than in the early crop. Primary inflorescences generally contained the highest glucosinolate levels in the early crop but secondary inflorescences had the highest levels in the late one.