Effect of post-harvest treatments on the level of glucosinolates in broccoli

Abstract

Broccoli is a very perishable vegetable with a high water content (around 88%) which leads to rapid dehydration and probably to an alteration in composition if conditions after harvest are not controlled. This study evaluates the glucosinolate pattern and glucosinolate levels in the principal and secondary in¯orescences of fresh broccoli cv`Tokyodome', and after being submitted to some situations which are likely to occur during or after harvest: room temperature (AE20°C) for 5 days, kept in the fridge at 4°C for 5 days, and frozen after blanching. Another set of material was harvested 5 days later, simulating a post-maturation stage, and analysed. The highest total glucosinolate content was found at commercial maturation with 20 888 and 20 355 mmoles kg À1 DW in the principal and secondary in¯orescences, respectively. Keeping the in¯orescences at room temperature caused the most signi®cant (P`0.05) reductions in total and individual glucosinolates, except for 4-hydroxyindol-3ylmethyl-, 2-hydroxy-2-phenylethyl-and 2-phenylethyl-, when compared to the other situations. The highest levels (10 925 mmoles kg À1 DW) of 4-methylsulphinylbutyl-, the precursor of the anti-cancer isothiocyanate sulphoraphane, were found in the in¯orescences freshly harvested at commercial stage. Refrigeration at 4°C and freezing were shown to be the best preservation processes for maintaining high levels of these and other glucosinolates in contrast with the other situations.

Handbook of Plant Food Phytochemicals

“…Storage of both primary and secondary broccoli florets (cv. Tokyodome) at either room temperature (~20 o C) or at 4 o C for 5 days showed that higher temperature storage led to a significant reduction in total and individual glucosinolates although levels of hydroxyglucobrassicin and gluconasturtiin increased [147]. Under refrigerated (4 o C) storage the decrease in total glucosinolates was considerably lower at 16% and 4% for primary and secondary inflorescences respectively.…”

“…Levels of total glucosinolates and levels of nine out of eleven individual glucosinolates measured were lower in post maturation florets in cv. Tokyodome, although slight increases in levels of hydroxyglucobrassicin and neoglucobrassicin were found [147]. In this study levels of glucosinolates were found to differ between primary and secondary florets, with primary florets containing higher levels of glucoraphanin, glucoiberin, progoitrin, glucoalyssin, gluconapin and gluconasturtiin than secondary florets.…”

“…italica group has also been reported. Most studies report glucoraphanin or less commonly glucobrassicin as the predominant glucosinolate in broccoli [22,71,75,83,87,131,147,155,177]. In the study of Schonhof et al (2004) glucobrassicin was the predominant glucosinolate in the purple variety Viola [155], whilst neoglucobrassicin was the predominant glucosinolate detected in 3 cultivars including cv.…”

“…Levels of total phenolics and antioxidant capacity was significantly lower in 8am harvested florets on day 3 of storage, but differences were not significant on other days [63]. Several studies [67,74,90,140,147,182] have examined the effect of post-harvest handling and storage conditions on glucosinolate and/or phenolic compounds in broccoli. Levels of glucoraphanin, quercetin and kaempferol in broccoli cv.…”

Physicochemical Quality Changes in Chinese Cabbage with Storage Period and Temperature: A Review

“…GSLs in particular are functional components unique to Brassicaceae crops Rodrigues and Rosa, 1999). The amount of GSLs varies throughout the plant-it is highest in the heart, followed by the stem and then the leaf (Shim et al, 1992).…”