Reviving Broccoli’s Cancer-Fighting Punch

Cancer fighting enzymes can be restored to frozen broccoli

(RxWiki News) It’s tough being a frozen vegetable. You’re picked, then scalded, then frozen so you can be stored for up to 18 months. What a way to go! All this strips the nutritional vigor of one of nature’s most powerful super heroes.

But never fear — scientists have now found a way to revive the cancer-fighting punch of frozen broccoli.

Lowering the blanching temperature 10 degrees is one way. The other is to sprinkle on a bit of a broccoli cousin called daikon radish.

"Eat fresh vegetables."

Elizabeth H. Jeffery, PhD, professor of nutrition at the University of Illinois, along with Edward B. Dosz, a graduate student in Dr. Jeffery's laboratory, discovered how to revitalize frozen broccoli.

Three to five servings of fresh broccoli are known to be protective against cancer because of a phytochemical called sulforaphane.

"We discovered a technique that companies can use to make frozen broccoli as nutritious as fresh,” Dr. Jeffery said in a prepared statement.

In the first study, researchers found that frozen broccoli isn’t as nutritious as fresh broccoli from the field because of the blanching process used to eliminate color, taste and aroma problems during the veggie’s 18-month shelf life.

Blanching (boiling briefly) before freezing and then the consumers' cooking of the broccoli inactivates an enzyme known as myrosinase which is necessary to form sulforaphane, the scientists found.

Three different brands of frozen broccoli were used in the experiments. The researchers tested the broccoli before and after cooking.

The scientists discovered that 82 percent of the myrosinase was preserved when the to-be-frozen broccoli was blanched at 76 degrees Celsius, instead of the typical 86 degrees Celsius that food processors used. This method didn’t compromise food safety or quality.

Next, the researchers tested a process they’d used successfully for other foods. They exposed the frozen broccoli to myrosinase from a daikon radish, which is in the same family of vegetables as broccoli.

In the study, 0.25 percent of daikon radish, which can’t be seen or tasted, was sprinkled on the frozen broccoli.

And voila! The cancer-fighting sulforaphane was formed.

"That means that companies can blanch and freeze broccoli, sprinkle it with a minute amount of radish, and sell a product that has the cancer-fighting component that it lacked before," Dosz said.

The good news didn’t stop there. The researchers found that the radish enzyme was able to withstand the heat from microwave cooking, so that the broccoli’s nutritional punch was maintained.

“What a unique and welcome innovation!” exclaimed Deborah Gordon, MD, a nutrition and preventive medicine expert who was not involved in this research.

“When researchers found that the process typically used for producing frozen broccoli had the unfortunate side effect of weakening its cancer-fighting powers, they found two completely natural techniques for maintaining broccoli's integrity and health benefits," said Dr. Gordon, who is a dailyRx Contributing Expert and an integrative physician at Madrona Homeopathy in Ashland, Oregon.

“Researchers call on broccoli producers to adopt one of the new practices, either using a slightly lower ‘blanching’ temperature for the broccoli, or introducing a more sturdy ingredient derived from one of broccoli's close relatives, daikon radish,” Dr. Gordon told dailyRx News.

Until these processing changes are made, the cancer-fighting benefits of broccoli can be boosted by adding other foods that contain myrosinase, the authors found.

Dr. Gordon suggests, "We, too, can choose to eat broccoli with any one of its close botanical neighbors and enhance its health benefits. A nice steak with horseradish and a side of broccoli and a salad that includes arugula, cabbage, and radishes would do it. Or, a stir-fry with daikon, broccoli, and mustard, served with wild salmon and a side of wasabi. The combinations are myriad thanks to broccoli's excellent family tree!"

Findings from this research were published in a recent issue of Journal of Functional Foods.

Funding came from the US Department of Agriculture and the National Institute of Food and Agriculture. No conflicts of interest were disclosed.

Review Date: 
August 12, 2013