Broccoli with lemon, olive and caper sauce.
Broccoli with lemon, olive and caper sauce. (Larry Crowe/AP Photo)

If you want the full health benefits of broccoli, bypass the freezer aisle, as new research suggests that the frozen variety lacks the cancer-fighting properties the vegetable is known for.

While busy families often reach for bags of frozen broccoli for the convenience factor, a team of US scientists has found that blanching or cooking the vegetable at high heat -- part of the flash-freezing process --   zapped the broccoli of myrosinase, a key enzyme needed to produce sulforaphane, the powerful cancer-preventive compound.

Sulforaphane is formed when fresh broccoli is chopped or chewed, a process that puts glucoraphanin and myrosinase into contact with one another.

After conducting a series of experiments, however, scientists from the University of Illinois noted that blanching the vegetables at a slightly lower temperature than the current industry standard could help preserve most of the enzyme myrosinase without compromising food safety and quality. Instead of 86C, scientists recommend heating the broccoli at 76C.

But not all is lost when it comes to frozen broccoli. The cancer-fighting compound can be unlocked in both its frozen and cooked state when paired with other foods that contain myrosinase.

For example, team frozen broccoli with raw radishes, cabbage, arugula, watercress, horseradish, spicy mustard or wasabi to give the bioactive compounds a kickstart, scientists say.


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As little as three to five servings of broccoli a week has been shown to have a cancer-protective benefit.