What makes cakes turn brown?

Many people find baked confectioneries such as cookies, cakes, pies, and muffins to be tainted with a greasy yellow-brown crust after a night in the oven. This phenomenon is known as rancidity or oxidation. Some ingredients that cause oxidative browning are oils such as corn oil, olive oil, and butterfat (also known as fat), but sugars such as dark brown sugar can also play a role.

Oxidation occurs when molecules from the food react with the oxygen in air (O-O). The reaction is called oxidation since some substances oxidize while chemically changing into other substances undergoing oxidation.

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