optimal preparation of broccoli

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http://www.aces.uiuc.edu/Discover/discover11.cfm

Maximizing the Anti-Cancer Power of Broccoli

University of Illinois researcher Jeffery has learned how

to maximize the cancer-fighting power of broccoli. It involves

heating broccoli just enough to eliminate a sulfur-grabbing protein,

but not enough to stop the plant from releasing an important cancer-

fighting compound called sulforaphane.

The discovery of this sulfur-grabbing protein in the Jeffery lab

makes it possible to maximize the amount of the anticarcinogen

sulforaphane in broccoli.

Jeffery's research will be published in an upcoming issue of

Phytochemistry. She is a professor in the Department of Food Science

and Human Nutrition at the U of I.

" As scientists, we learned that sulforaphane is maximized when

broccoli has been heated 10 minutes at 140 degrees Fahrenheit, " said

Jeffery. " For the consumer, who cannot readily hold the temperature

as low as 140 degrees, that means the best way to prepare broccoli is

to steam it lightly about 3 or 4 minutes--until the broccoli is tough-

tender. "

Frozen-food manufacturers may use this technology to increase the

health benefits of the broccoli they sell, allowing the consumer to

heat it without having to worry about the conditions.

Jeffery said that sulforaphane is one of the most powerful

anticarcinogens found in food. " It works by increasing the enzymes in

your liver that destroy the cancer-inducing chemicals you ingest in

food or encounter in the environment. "

But the chemistry for triggering the release of sulforaphane is

tricky. Sulforaphane is linked to a sugar molecule through a sulfur

bond. When the broccoli enzyme breaks off the sugar to release the

sulforaphane, a sulfur-grabbing protein can remove the newly exposed

sulfur on the sulforaphane and inactivate it.

" Although our gut bacteria may be able to release some of the

sulforaphane, we don't have the enzyme to release sulforaphane in our

body tissues, so our best bet is to use the enzyme in the broccoli, "

Jeffery said. " The enzyme in the broccoli does a really good job of

breaking that bond. You can break it simply by chopping the broccoli. "

Jeffery's team of researchers began by cooking broccoli for different

lengths of times at different temperatures to learn the point at

which the broccoli enzyme that releases sulforaphane is destroyed.

" And, much to our excitement, after we had heated it for just a

little while, we found we had killed off a protein that nobody knew

was there. This protein, named the epithiospecifier protein, had been

grabbing sulfur and greatly depleting the amount of sulforaphane in a

serving of broccoli.

" The protein was very heat-sensitive, and with a little bit of heat,

we killed it off and got an almost perfect yield of sulforaphane, the

cancer-fighting component, " she said.

" It was a serendipitous discovery, and it changed our focus. Instead

of worrying about overcooking the broccoli and losing the enzyme that

releases the sulforaphane, we focused on heating the broccoli just

enough to destroy the sulfur-grabbing protein, but not enough to harm

the enzyme that releases sulforaphane from the sugar, " said Jeffery.

Other researchers at the University of Illinois who contributed to

the study were Matusheski and Qinyan Qiao.

http://www.fshn.uiuc.edu/dept/person.cfm?id=90

http://www.sciencedaily.com/releases/2005/03/050326114810.htm