The optimal time and temperature for heat-shocking fruits and vegetables varies in response to many factors — in particular, whether they were already treated before purchase. Use these as general guidelines:
Asparagus: 2 to 3 minutes at 131 F (55 C).
Broccoli: 7 to 8 minutes at 117 F (47 C).
Cantaloupe (whole): 60 minutes at 122 F (50 C).
Celery: 90 seconds at 122 F (50 C).
Grapes: 8 minutes at 113 F (45 C).
Kiwi fruit: 15 to 20 minutes at 104 F (40 C).
Lettuce: 1 to 2 minutes at 122 F (50 C).
Oranges (whole): 40 to 45 minutes at 113 F (45 C).
Peaches (whole): 40 minutes at 104 F (40 C).
Nothing is more frustrating than finding the perfect cucumber or head of lettuce at the farmers market, paying top-dollar for it, and then … tossing it out a week later when it has gone moldy or slimy in the refrigerator.
No doubt one reason so many of us eat too many convenience foods and too few fruits and vegetables is that it can be hard to get our busy schedules in sync with the produce we bring home with the best of intentions.
Food scientists, however, have discovered a remarkably effective way to extend the life of fresh-cut fruits and vegetables by days or even a week. It doesn’t involve the chlorine solutions, irradiation or peroxide baths sometimes used by produce packagers. And it’s easily done in any home by anyone.