Agricultural practices have changed in the past few decades to the point that produce must now travel distances of up to 3,000 miles from farm to table. According to a study conducted by the Institute of Food Research and reported by "NY Daily News" on March 5, 2010, up to 45 percent of nutrients in fresh vegetables are lost by the time they reach your plate. Frozen vegetables retain many of their nutrients and can be an easy way to help you get your recommended daily healthy dose. There is no conclusion that frozen vegetables are better than fresh ones, but if there is limited accessibility to local produce, frozen may be a good alternative.
Nutrient Preservation
The nutrients of fresh vegetables begin to deteriorate from the instant they are harvested. Results from the Institute of Food Research presented in the NY Daily News reveals that fresh vegetables such as green beans lose 45 percent of their nutrients; broccoli and cauliflower, 25 percent; carrots, 10 percent; and peas up to 15 percent after 16 days of storage. With fresh vegetables, you never know how long it has been since they were picked and the amount of nutrients that were lost en route to the market unless you are buying from a local farmer. With vegetables that are frozen in their prime, you can savor most of the nutrients that were present at the time of freezing.
Vitamins and Antioxidants
A comparison among different green vegetables published in "Food Chemistry" in 2003 by the National Technical University of Athens show that the type of plant tissue significantly affects the rate of vitamin C degradation during the freezing. Frozen spinach presents itself to be the most susceptible to losing vitamin C and peas and green beans show a moderate degradation, whereas okra exhibits substantial retention. Choosing a less leafy fresh vegetable at the market may be your best bet for more vitamin C. Another study published in the "Journal of Agricultural and Food Chemistry" demonstrates that fresh vegetables in the Brassica family, such as cabbages and mustard vegetables, retain phytochemicals and total antioxidant capacity better than frozen vegetables.
Preparing Your Vegetables
Thawing vegetables before cooking is unnecessary and causes more vitamin C loss according to a study done in Turkey at Hacettepe University published in "Nahrung" with frozen spinach, peas, green beans and okra. These vegetables were commercially cooked with and without thawing in three different stew pans. To prevent vitamin C loss when cooking frozen vegetables, use a stainless steel double boiler and steam them with minimum amounts of water. According to the "Journal of Agricultural and Food Chemistry," chlorophyll, a potent polyphenol in vegetables, is more stable in frozen vegetables than in fresh ones, even though steaming methods better preserve these compounds in fresh vegetables than any other cooking method.
Save Time and Money
With the limited amount of time many people have in a busy day, meals are made easier when prepared using frozen vegetables that are already cut up. Frozen vegetables can help you achieve the recommended vegetable intake of three to five servings a day. A serving, according to the American Dietetic Association, is 1/2 cup of cooked vegetables or 1 cup of raw vegetables. Also, frozen vegetables will keep in the freezer for a longer period of time as enzymes involved in the ripening process are deactivated by the blanching process prior to freezing, which slows down deterioration. Blanching also destroys pathogens that may lead to food-borne illnesses on the surface of the vegetable, which also make frozen vegetables safer for those who are immuno-compromised.
References
- NY Daily News: Frozen Vegetables Are More Nutritious Than Fresh, Study Says; March 5th, 2010.
- "Food Chemistry"; Kinetic modelling of vitamin C loss in frozen green vegetables under variable storage conditions; Giannakourou, et al; 83 (1) 2004.
- "Journal of Agriculture and Food Chemistry"; Polyphenols and Antioxidant Capacity of Vegetables under Fresh and Frozen Conditions; Paolino Ninfali, et al.; 51 (8), 2003.
- "Journal of Agriculture and Food Chemistry"; Effect of Different Cooking Methods on Color, Phytochemical Concentration, and Antioxidant Capacity of Raw and Frozen Brassica Vegetables; Nicoletta Pellegrini, et al.; 58 (7), 2010.
- "Nahrung"; Vitamin C losses in some frozen vegetables due to various cooking methods; Nursal B, et al.; 44 (6), 2000.
- University of Minnesota: Freezing Fruits and Vegetables; William Schafer; 2009.
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