While cooked berries do beat raw berries in some nutrient categories, they are not as beneficial overall as are other forms. Fresh, frozen and dried blueberries receive top scores when it comes to antioxidants that protect against heart disease and cancer. Those berries beat all the vegetables and most other fruits on a Tufts University antioxidant food chart, according to "UC Berkeley Wellness Letter."
Vitamins
Cooked and raw blueberries contain similar amounts of most vitamins, with the exception of vitamin C. One cup of raw blueberries contains 14 mg of vitamin C versus 1 mg in 1 cup of cooked blueberries. Amounts of thiamin, niacin, pantothenic acid, vitamin B-6, vitamin A and carotene in raw and cooked blueberries are all very similar. Cooked blueberries exceed raw blueberries by small amounts in riboflavin and vitamin E, while raw blueberries exceed cooked blueberries in folate, according to the USDA.
Minerals
Cooked blueberries provide more minerals than raw berries overall, with the difference greatest for calcium, where cooked berries contain 15 mg of calcium and raw berries contain 9 mg. For other minerals, such as magnesium and zinc, the difference between cooked and raw berries is minor. Cooked berries exceed raw berries in phosphorus, with 29 mg for cooked versus 18 mg for raw; in potassium levels, 132 mg are in cooked blueberries versus 114 mg for raw.
Antioxidants
Micronutrients called polyphenols exist in all fruits and vegetables in varying degrees. These polyphenols create antioxidants, which play a role in preventing serious diseases such as cancer and heart disease. Blueberries are among the fruits with the highest content of polyphenols. Because polyphenols often appear in the skin of fruits and vegetables, cooking causes significant losses of these nutrients. Boiling and microwaving cause the most losses in polyphenols, and steaming causes the least amount of loss, according to a May 2004 article by French researchers on polyphenols in "The American Journal of Clinical Nutrition."
Cooking Methods
In an article published in the "Journal of Food Science," researchers from the University of Illinois Urbana-Champaign echoed the findings of the French researchers, reporting that harsh cooking methods are most responsible for the decrease of antioxidant compounds in blueberries. Less harsh methods, such as stuffing fish with whole blueberries, result in less loss of antioxidants, according to a 2009 study on blueberries published in the "Journal of Agricultural and Food Chemistry."
Substituting a partially cooked blueberry pie for a traditional pie solves the problem to some degree. Instead of cooking blueberries in a traditional pie, cook one-third of the berries in a cornstarch-thickened sauce and pour the sauce over the other two-thirds of fresh berries in a pre-baked pie crust. Chill the pie for a few hours in the refrigerator to set.
References
- "UC Berkeley Wellness Letter"; Plant Pigments -- Color Yourself Healthy; November 1999
- USDA: National Nutrient Database for Standard Reference
- "The American Journal of Clinical Nutrition"; Polyphenols: Food Sources and Bioavailability; Claudine Manach, et al.; May 2004
- "Journal of Food Science"; Effects of Food Processing on Blueberry Antiproliferation and Antioxidant Activity; Barbara M. Schmidt, et al.; May 2006
- "Journal of Agricultural and Food Chemistry"; Degradation of Anthocyanins and Anthocyanidins in Blueberry Jams/Stuffed Fish; F. Queiroz, et al.; November 2009
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