With flavors that range from mildly sweet (cultivated) to tart and tangy (wild), blueberries are nutritional stars bursting with nutrition and flavor while being very low in calories.
Choose blueberries that are firm and have a lively, uniform hue colored with a whitish bloom. Shake the container, noticing whether the berries have the tendency to move freely; if they do not, this may indicate that they are soft and damaged or moldy. Avoid berries that appear dull in color or are soft and watery in texture. They should be free from moisture since the presence of water will cause the berries to decay. When purchasing frozen berries, shake the bag gently to ensure that the berries move freely and are not clumped together, which may suggest that they have been thawed and refrozen. Blueberries that are cultivated in the United States are available from May through October while imported berries may be found at other times of the year.
Store ripe blueberries in a covered container in the refrigerator where they will keep for up to 3 days. If kept out at room temperature for more than a day, the berries may spoil.
Ripe berries can also be frozen, although this will slightly change their texture and flavor. Before freezing, wash, drain and remove any damaged berries. To better ensure uniform texture upon thawing, spread the berries out on a cookie sheet or baking pan, place in the freezer until frozen, then put the berries in a plastic bag for storage in the freezer.
Blueberries are an excellent source of bone-healthy vitamin K and a very good source of free radical-scavenging vitamin C and manganese. Blueberries are also a good source of heart-healthy fiber.