Without added sugar, one-half cup of blueberries contains only 45 calories. They provide fiber, Vitamins A and C, potassium and iron. Berries of low quality are soft and watery or have a shriveled appearance. Color, which may be blue, black, bluish-black or purple is the key to ripeness. Look for berries that have a uniform color.
Blueberries usually have a grayish waxy deposit on the skin, which is called bloom .
The amount of bloom present depends on the variety of the berry. Blueberries will spoil quickly if left at room temperature. They can, however, be stored for several days in the refrigerator. Canning or freezing blueberries will extend shelf life and provide your family with blueberries throughout the year. Pack blueberries in moisture-proof wrap and place in the refrigerator immediately to maintain peak quality.