Hot-water shock can extend life of produce
Source: Agencies |
April 6, 2013, Saturday
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Print Edition
Print Edition
NOTHING is more frustrating than finding the perfect cucumber or head of lettuce at the 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.
This method, called heat-shocking, is 100 percent organic and uses just one ingredient that every cook has handy - hot water.
You may already be familiar with a related technique called blanching, a cooking method in which food is briefly dunked in boiling or very hot water. Blanching can extend the shelf life of broccoli and other plant foods, and it effectively reduces contamination by germs on the surface of the food. But blanching usually ruptures the cell walls of plants, causing color and nutrients to leach out. It also robs delicate produce of its raw taste.
Heat-shocking works differently. When the water is warm but not scalding - temperatures ranging from 40 degrees Celsius to 60 degrees work well for most fruits and vegetables - a brief plunge won't rupture the cells.
A long list of scientific studies published during the past 15 years reports success using heat-shocking to firm potatoes, tomatoes, carrots, and strawberries; and to preserve the color of asparagus, broccoli, green beans, kiwi fruits, celery, and lettuce, among others.
The procedure is quite simple. Just let the water run from your tap until it gets hot, then fill a large pot of water about two-thirds full, and use a thermometer to measure the temperature. Submerge the produce and hold it for several minutes, then drain, dry and refrigerate as normally.
Researchers still are working out the details of how heat-shocking works but for the home cook, the inner workings don't really matter. The bottom line is that 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.
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.
This method, called heat-shocking, is 100 percent organic and uses just one ingredient that every cook has handy - hot water.
You may already be familiar with a related technique called blanching, a cooking method in which food is briefly dunked in boiling or very hot water. Blanching can extend the shelf life of broccoli and other plant foods, and it effectively reduces contamination by germs on the surface of the food. But blanching usually ruptures the cell walls of plants, causing color and nutrients to leach out. It also robs delicate produce of its raw taste.
Heat-shocking works differently. When the water is warm but not scalding - temperatures ranging from 40 degrees Celsius to 60 degrees work well for most fruits and vegetables - a brief plunge won't rupture the cells.
A long list of scientific studies published during the past 15 years reports success using heat-shocking to firm potatoes, tomatoes, carrots, and strawberries; and to preserve the color of asparagus, broccoli, green beans, kiwi fruits, celery, and lettuce, among others.
The procedure is quite simple. Just let the water run from your tap until it gets hot, then fill a large pot of water about two-thirds full, and use a thermometer to measure the temperature. Submerge the produce and hold it for several minutes, then drain, dry and refrigerate as normally.
Researchers still are working out the details of how heat-shocking works but for the home cook, the inner workings don't really matter. The bottom line is that 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.
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