Durk Pearson & Sandy Shaw’s®
Life Extension NewsTM
Volume 15 No. 8 • December 2012


A fruit is a vegetable with looks and money. Plus, if you let fruit rot, it turns into wine, something Brussels sprouts never do.
— P. J. O’Rourke

You Don’t HAVE to Buy Broccoli But if You Do: Here’s a Tip on How To Cook Broccoli To Maximize Sulforaphane Yield

It is not generally common knowledge concerning the best method for cooking and how long one should cook various vegetables in order to get optimal amounts of highly desirable phytonutrients. Of course one could eat vegetables raw, but cooking, rather than eating raw, is really the prudent course because of the ever present danger of getting food poisoning from bacterial contamination of vegetables, which is very common.

That’s why we were glad to see information in the latest issue of the Journal of Agricultural and Food Chemistry1 on preparing broccoli in order to get the best yield of sulforaphane, the powerful anti-cancer component contained in it.

As the researchers explained, in broccoli the glucosinolate glucoraphanin is converted by the enzyme myrosinase into sulforaphane. But a myrosinase cofactor can direct the hydrolysis of glucoraphanin away from the production of sulforaphane to an inactive product sulforaphane nitrile. The cofactor is more heat sensitive than myrosinase, so by controlling the amount of heat and the length of time the food is heated it is possible to generate more of the sulforaphane, avoiding the undesired nitrile. The researchers processed four different broccoli cultivars and found that with boiling and microwave heating, there was an initial loss of nitrile with an increase in sulforaphane; this was then followed by loss of sulforaphane and all this took place within a minute. They then found that steaming the broccoli for between 1 and 3 minutes in three of the four cultivars led to an enhanced yield of sulforaphane with less nitrile as compared to the boiling and microwaving.

Hence, the maximum sulforaphane yield was reached following a much shorter heating period for microwave heating or boiling than for steaming. In fact, the researchers had to use an ice-water bath to rapidly stop the heating process after microwave or boiling. The authors of the study, therefore, recommend that “steaming for 1.0–3.0 min. enhanced SF [sulforaphane] levels in all but Brigadier [one of the broccoli cultivars] and therefore can be expected to enhance the health benefits of a broccoli meal.”1 They recognize that broccoli sold at supermarkets does not identify the cultivar, but in the absence of that information suggest that their best recommendation is that steaming for 1–3 min. will provide the greatest SF availability.

This research was supported by a grant from the U.S. Dept. of Agriculture, which perhaps wants to encourage the eating of broccoli. Good idea. Another good idea would be to let the growers of broccoli pay for the research (rather than taxpayers via regulatory agencies) as the sellers of broccoli will profit directly from its sales—if the FDA would allow them to make truthful nonmisleading health claims …

Reference

  1. Wang et al. Impact of thermal processing on sulforaphane yield from broccoli (Brassica oleracea L. ssp. italica). J Agric Food Chem 60:6743-8 (2012).

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