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Mooshee - OK, we all heard from food enthusiasts that veggies should
be eaten pretty much raw, but now some experts at the University of
Warwick (UK) have put broccoli to the test and found out that this
whole don't-boil-your-vegetables thing might be true after all, at
least for brassica vegetables, (broccoli, brussel sprouts,
cauliflower... etc).

Researchers at the University of Warwick have found that the standard
British cooking habit of boiling vegetables severely damages the
anticancer properties of many Brassica vegetables such as broccoli,
Brussel sprouts, cauliflower and green cabbage.

Past studies have shown that consumption of Brassica vegetables
decreases the risk of cancer. This is because of the high
concentration in Brassicas of substances known as glucosinolates which
are metabolized to cancer preventive substances known as
isothiocyanates. However before this research it was not known how the
glucosinolates and isothiocyanates were influenced by storage and
cooking of Brassica vegetables.

The researchers, Prof Paul Thornalley from Warwick Medical School at
the University of Warwick and Dr Lijiang Song from the University of
Warwick's Department of Chemistry bought Brassica vegetables,
(broccoli, Brussel sprouts, cauliflower and green cabbage) from a
local store and transported them to the laboratory within 30 minutes
of purchasing. The effect of cooking on the glucosinolate content of
vegetables was then studied by investigating the effects of cooking by
boiling, steaming, microwave cooking and stir-fry.

Boiling appeared to have a serious impact on the retention of those
important glucosinolate within the vegetables. The loss of total
glucosinolate content after boiling for 30 minutes was: broccoli 77%,
Brussel sprouts 58%, cauliflower 75% and green cabbage 65%.

The effects of other cooking methods were investigated: steaming for
0-20 min, microwave cooking for 0-3 min and stir-fry cooking for 0-5
min. All three methods gave no significant loss of total glucosinolate
analyte contents over these cooking periods.

Domestic storage of the vegetables at ambient temperature and in a
domestic refrigerator showed no significant difference with only minor
loss of glucosinolate levels over 7 days.

However the researchers found that storage of fresh vegetables at much
lower temperatures such as -85 °C (much higher than for storage in a
refrigerator at 4-8 °C) may cause significant loss of glucosinolates
up to 33% by fracture of vegetable material during thawing.

The researchers found that preparation of Brassica vegetables had
caused only minor reductions in glucosinolate except when they were
shredded finely which showed a marked decline of glucosinolate levels
with a loss of up to 75% over 6 hours after shredding.

Professor Thornalley said: "If you want to get the maximum benefit
from your five portions-a-day vegetable consumption, if you are
cooking your vegetables boiling is out. You need to consider stir
frying steaming or micro-waving them."

http://www.mooshee.com/article-2996520.htm

Tim Silva