Hi, Patti. I think you might have two different processes jumbled up here, although both involve oxygen molecules. Oxidation is the process where fats (or metals) take on oxygen molecules and thereby become rancid (or rusty). Batters in general aren't kept around long enough to oxidize - it's a process that takes place over weeks or months. Batters that depend on chemical leavening are raised by the interaction of acid and base to make carbon dioxide, the gas that makes them rise. It's possible for a batter made with baking soda (base) and acidic ingredients (buttermilk) to lose some of its raising power if it sits around for too long, as the reaction between this ingredients slowly takes place while the batter sits. Baking soda reacts in the presence of acid, but the reaction is slowed by refrigeration; that's why I answered above that a batter that's kept overnight or even as long as a few days in the refrigerator will still rise when it's cooked. Susan

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