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http://www.environmentalnutrition.com
Q. I don't always have a chance to buy fresh fruits and vegetables. Do frozen and canned count towards the daily goal of five a day?
A. Most certainly. A popular misconception is that all processed foods are devoid of nutritional value. It's true that the heat used in canning sometimes causes a loss of certain vitamins. But careless transportation, improper store displays or home storage, and even prolonged cooking of fresh produce at home can lead to vitamin losses, often to a greater extent than processing does.
Commercially processed fruits and vegetables are often canned or frozen at the farm immediately after harvesting. This promptness often preserves more nutrients than can be found in fresh fruits and vegetables that have been improperly stored in transit, at the market or at home.
Last year, the University of Illinois Department of Food Science and Human Nutrition conducted a study analyzing the nutritive values of 14 different fresh, canned and frozen fruits and vegetables. The results confirmed that, in most cases, canned or frozen fruits and vegetables are nutritionally comparable to their prepared fresh counterparts.
The difference for canned vegetables, of course, is their sodium content, which is usually much higher than in frozen or fresh. Still, in many cases, there is little nutritional difference, for example:
• Canned peaches provide about the same percentages of the Daily Value (DV) for vitamin C and vitamin A (as beta-carotene) as fresh. Frozen peaches actually contain slightly more C, since ascorbic acid (vitamin C) is added to maintain color.
• Canned apricots--an excellent source of beta-carotene--are comparable to fresh.
• A U.S. Department of Agriculture study found that the vitamin and mineral levels in cooked frozen spinach were very close to those of cooked fresh spinach.
• Processed tomatoes--canned, jarred, even tomato juice--are brimming with lycopene, a carotenoid with twice the antioxidant power of beta-carotene.
• A serving of canned potatoes provides about 20% to 25% of the DV for vitamin C.
Get the most nutrition out of your canned or frozen fruits and vegetables by paying attention to a few simple buying, storage and cooking practices:
• Avoid buying bulk bags of frozen fruits and vegetables if the product inside is clumped together in a solid brick. What's inside should move about freely. Also, avoid boxed frozen fruits or vegetables with colored stains or leaking liquid. These are all signs that thawing and refreezing have taken place, causing a loss of quality and possibly of nutrients.
• Use frozen vegetables within six months of purchase. Use canned kidney beans and other legumes within 18 months and other canned vegetables within two years.
• Store canned fruits and vegetables in a cool, dry place such as a pantry or basement, away from radiators, furnaces, hot pipes or the kitchen range. About 25% of vitamin C may be lost if canned vegetables are stored at 80degreesF for a year versus only a 10% loss if stored at 65degreesF.
• Microwave frozen vegetables in little or no water for maximum nutrition. Steaming is next best, because vegetables do not come in direct contact with water, which would cause water-soluble nutrients, like B vitamins, to leach out.
Heat canned vegetables in their own liquid until just warmed. Use leftover liquid for soups and sauces; it typically contains one-third of a vegetable's nutrients.
