Preparing Blackberries

Rinse the berries under cool running water, then drain them and pick them over carefully to remove all stems and leaves.

What Happens When You Cook Blackberries

Cooking destroys some of the vitamin C in fresh blackberries and lets water-soluble B vitamins leach out. Cooked berries are likely to be mushy because the heat and water dissolve their pectin and the skin of the berry collapses. Cooking may also change the color of blackberries, which contain soluble red anthocyanin pigments that stain cooking water and turn blue in basic (alkaline) solutions. Adding lemon juice to a blackberry pie stabilizes these pigments; it is a practical way to keep the berries a deep, dark reddish blue.

How Other Kinds of Processing Affect Blackberries

Canning. The intense heat used in canning fruits reduces the vitamin C content of blackberries. Berries packed in juice have more nutrients, ounce for ounce, than berries packed in either water or syrup.

Adverse Effects Associated with Blackberries

Allergic reactions. Hives and angioedema (swelling of the face, lips, and eyes) are common allergic responses to berries, virtually all of which have been known to trigger allergic 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.