Are frozen vegetables processed food?

The answer is Yes.

Frozen vegetables are processed through the following steps (Ref 1):

Harvest - Factory receiving and quality checks - Sifting and Washing - Blanching - Freezing - Weighing and Bagging - Quality Control - Delivery

The current industry standard of blanching is set at 86ºC. Take an example of broccoli. Blanching practically kills enzyme myrosinase, which is necessary to form sulforaphane, one of the powerful cancer-preventive compounds in broccoli.

However, Illinois scientists (Ref 2) suggest either lowering the temperature to 76ºC or adding 0.25 percent of Daikon radish on the frozen broccoli. The first remedy help preserve 82% of the enzyme. And the second one works by adding the enzyme myrosinase from Daikon radish onto the frozen broccoli to form sulforaphane.

In addition to Daikon radish, cabbage, arugula, watercress, horseradish also contain myrosinase. So sprinkle a tiny amount of these raw vegetables to frozen cooked broccoli and you will still get the cancer fighting phytochemical sulforaphane.