What causes an otherwise scrumptious-looking blueberry baked beauty to turn green? (Sometimes the green forms a ring around the berries, and sometimes it spreads into the crumb. Either way, I’m sure my baking friends agree…we’re proud to be green-free.)
Blueberries get their lovely color from pigments called anthocyanins. Anthocyanins are susceptible to changing color when exposed to various pH levels. At a low (acidic) pH they are pinkish, at neutral (basic) pH they are purple/ish, and at high (basic) pH they are green/yellowish.
Your baking recipes have different pH levels. An ingredient like lemon juice is an obvious acid to add to your recipe. But, did you know that ingredients like yogurt, coffee, chocolate, berries, honey, cream of tartar, and different leaveners (baking soda/baking powder) can also impact the pH of your recipe? And when the pH of the recipe changes, so can the color of those blueberry pigments. Often, blueberry goodies are turned green due to the recipe having too much baking soda.
These blueberry scones were excellent. I think I ate my day’s worth of calories in scones! For the recipe, visit Sallys Baking Addiction. I didn’t have heavy cream on hand, so substituted 2% milk (and tossed in an extra tablespoon of butter).
Food Science Tid-Bite: Want to bake with fresh blueberries, but afraid of the green? Try using a recipe like the blueberry scones featured here which includes only baking powder. (Read the difference between baking powder and baking soda here.) Or, consider the acidic ingredients in your recipe – remember more acid will lower the recipe’s pH.
Source: How Baking Works: Figoni, Paula. Exploring the Fundamentals of Baking Science. Hoboken, NJ: John Wiley & Sons, Inc., 2011