Another easy method to freeze berries is to arrange them in a single layer on a cookie sheet and place in the freezer. When frozen, transfer the blueberries to a freezer container or ziplock bag. Frozen blueberries make great snacks. Do not wash the berries until just prior to using. Blueberry Baking Basics Blueberries may change color when cooked.
Blueberries also contain yellow pigments.
In an alkaline environment, such as a batter with too much baking soda, the yellow and blue pigments will turn the blueberries greenish-blue. Using hard, frozen blueberries in batters will reduce the amount of color streaking. For pancakes and waffles, add the blueberries as soon as the batter has been poured on the griddle or waffle iron. This will give the product a better appearance and make it easier to turn. If frozen blueberries are used, increase cooking time to make sure the berries are heated thoroughly.