Rinse the berries under cool running water, then drain them and pick
them over carefully to remove all stems, leaves, and hard (immature) or
soft (over-ripe) berries.
Happens When You Cook Blueberries
Cooking destroys some of the vitamin C in fresh blueberries and lets
water-soluble B vitamins leach out. Cooked berries are likely to be
mushy because heat dissolves the pectin inside.
Blueberries may also change color when cooked. The berries are
colored with blue anthocyanin pigments. Ordinarily, anthocyanin-pigmented
fruits and vegetables turn reddish in acids (lemon juice, vinegar) and
deeper blue in bases (baking soda). But blueberries also contain yellow
pigments (anthoxanthins). In a basic (alkaline) environments, as in a
batter with too much baking soda, the yellow and blue pigments will
combine, turning the blueberries greenish blue. Adding lemon juice to a
blueberry pie stabilizes these pigments; it is a practical way to keep
the berries a deep, dark reddish blue.
Other Kinds of Processing Affect Blueberries
Canning and freezing. The intense heat used in canning the fruit or
in blanching it before freezing reduces the vitamin C content of
blueberries by half.
Medical Uses and/or Benefits
Reduced risk of heart disease, cancer, decline of brain function, and
other diseases of aging. Antioxidants, such as vitamin C, prevent free
radicals, fragments of molecules, from hooking up with other fragments
to produce compounds that damage body cells and may cause heart disease,
cancer, memory loss, and other conditions associated with aging or
In 1996, researchers at the USDA Jean Mayer Human Nutrition Research
Center on Aging at Tufts University (Boston) showed that, ounce for
ounce, blueberries, spinach, and strawberries were the most potent
antioxidants of 40 foods tested.
In a second series of studies the following year, the scientists fed
aging rats a diet of chow alone or chow plus extract of blueberries,
strawberries, or spinach. In the end, the diet with added blueberry
extract was most effective in slowing oxygen-related changes. NOTE: The
antioxidant ranking of these foods may vary depending on growing
conditions, season, and other variables.
Urinary antiseptic. A 1991 study at the Weizmann Institute of Science
(Israel) suggests that blueberries, like CRANBERRIES, contain a compound
that inhibits the ability of Escherichia coli, a bacteria commonly
linked to urinary infections, to stick to the wall of the bladder. If it
cannot cling to cell walls, the bacteria will not cause an infection.
This discovery lends some support to folk medicine, but how the berries
work, how well they work, or in what "dosages" remains to be proven.
Effects Associated with Blueberries
Allergic reaction. Hives and angiodemea
(swelling of the face, lips, and eyes) are common allergic responses to
berries, virtually all of which have been reported to trigger these
reactions. According to the Merck Manual, berries are one of the 12
foods most likely to trigger classic food allergy symptoms. The others
are chocolate, corn, eggs, fish, legumes (peas, lima beans, peanuts,
soybeans), milk, nuts, peaches, pork, shellfish, and wheat.