Why would sweet potato bread turn green?

The green color on sweet potato bread is due to the presence of a compound called chlorogenic acid. Chlorogenic acid is a polyphenol compound that is naturally present in sweet potatoes. When this compound is exposed to air, it can oxidize and turn brown. However, when sweet potato bread is baked, the chlorogenic acid can also react with the baking soda and produce a green color. This reaction is more likely to occur if the sweet potato bread is over-baked or if the baking soda is not properly dissolved.