Natural and Easy Way to Preserve Produce

April 26, 2013

Do you have good intentions to eat more fruits and veggies, but by the time you go to use them they are wilted and moldy? Find out an easy way to preserve your produce here

Food scientists, have discovered a remarkably effective way to extend the life of fresh-cut fruits and vegetables by days or even a week. No chemicals involved! And it’s easy!

It’s called heat-shocking and uses just one ingredient that we all have handy – hot water. Heat-shocking is different than blanching - which can extend the shelf life of plant foods, as it effectively reduces contamination by germs on the surface of the food- the difference is, blanching usually damages the cell walls of plants, causing color and nutrients to leach out. Heat-shocking does not deplete the nutrition content of the foods.

Heat-shocking uses warm but not scalding water. The right amount of heat alters the biochemistry of the tissue in ways that, for many kinds of produce, firm the flesh, delay browning and fading, slow wilting, and increase mold resistance.

A variety of studies published during the past 15 years report success using heat-shocking to firm potatoes, tomatoes, carrots, and strawberries; to preserve the color of asparagus, broccoli, green beans, kiwi fruits, celery, and lettuce; to fend off overripe flavors in cantaloupe and other melons; and to generally add to the longevity of grapes, plums, bean sprouts, and peaches, among others.

How does it work? Researchers are still working out the details of how heat-shocking works, but it appears to change the food in several ways at once. Quick heat tends to slow the rate at which fruits and veggies respire and produce ethylene, a gas that plays a role in the ripening of produce. In leafy greens, the shock of the hot water also seems to turn down production of enzymes that cause browning around wounded leaves, and to turn up certain proteins, which can have preservative effects. The bottom line is, soaking your produce in hot water for a few minutes after you unpack it makes it cheaper and more nutritious because more fruits and veggies will end up in your family rather than in the trash.

The optimum time and temperature combination for the quick dip depends on various factors, but the procedure is quite simple. Just let the water run from your tap until it gets hot, fill a large pot of water about two-thirds full, and use a thermometer to measure the temperature. It will probably be between 105 F and 140 F; if not, a few minutes on the stove should do the trick. Submerge the produce and hold it there for the times mentioned below (the hotter the water, the less time is needed), then drain, dry and refrigerate as you normally would.

The optimal time and temperature for heat-shocking fruits and vegetables varies. 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)
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)

Information for this article gathered from The Associated Press.