Green blueberries ???
No, it is not an Irish specialty for the St Patrick’s celebrations. This may happen when you bake using blueberries.
Why would a deep, dark blue fruit turn green when baking it?
This could happen if the muffin mix contains too much baking soda or if the soda isn’t evenly mixed in the dough or batter. This would result in some alkaline pockets throughout the mix which could get in contact with the fruits.
Bilberries and blueberries are rich in anthocyanin pigments specially under their skin. These pigments are extremely sensitive to PH changes and are generally associated with acidic fruits. They are concentrated in cell vacuoles as in purple beans or sometimes, just in a superficial layer of cells under the fruit skin, as in grapes or blueberries.
In the fruit, these anthocyanins are surrounded by a acidic environment as the pulp of the berries is quite rich in hydrogen. When you add the berries into the muffin batter their skin may break allowing the soda in the alkaline pockets to get in contact with the pulp and the anthocyanin pigments. The result of this action will be the elevation of the PH therefore changing the pigmentation of the anthocyanin. Turning the dark blue of the blueberries into a greenish pigment.
This is not as mouth watery looking!
So, to avoid this to happen, make sure that all the dry ingredients are mixed well together before adding any liquid into your muffin or other type of cake mixes and batters.
“un homme averti, en vaut deux”