Magic color changing blueberry residue
August 8, 2009 6:18 PM Subscribe
You buy a bag of delicious frozen blueberries and empty its contents into a plastic tub which you keep in the freezer. When the last of the berries have been consumed, a light pinkish-red residue remains in the tub. You proceed to rinse out the container, and after a few seconds under running water the color suddenly and dramatically changes to a deep dark blue. Why?
posted by Rhomboid to food & drink (14 answers total) 8 users marked this as a favorite
The wikipedia article on anthocyanins
mentions that the difference in chemical structure that occurs in response to changes in pH is the reason why anthocyanins are often used as pH indicator, as they change from red in acids to blue in bases
. Does simply diluting the blueberry-goo with water really alter the pH that significantly? Or is something else at work here?