Blue-Green Streaks in Baked Goods? Aluminum in Baking Powder May Be the Cause

This article was prepared from the source material provided, which did not include interviews, laboratory testing, or official statements.

Blue and green streaks running through fruit scones or peach cupcakes are a common baking problem, and the cause is usually not the recipe or the baker. According to the source material, the discoloration almost always comes from baking powder that contains aluminum. When that type of baking powder reacts with acidic ingredients, it produces the streaks and can leave what many people describe as a tinny or metallic taste.

The fix is straightforward: replace the aluminum-based baking powder with an aluminum-free brand. The source names Rumford and Bob's Red Mill as options. It also notes that Rumford's parent brand, Clabber Girl, makes a baking powder that does contain aluminum, so checking the label matters.

The source does not specify which acidic ingredients trigger the reaction most often, how much baking powder is needed to cause visible discoloration, or whether the metallic taste occurs in every case. Those details remain unaddressed in the available material.