Storing cake batter

The exact outcome of holding your batter will vary depending on the particular type of cake you are making, but in general the results will be sub-optimal. This is why you don't see blog articles about making the batter up on a weekend, and having fresh cupcakes all week.

Almost all cupcakes freeze extremely well, though, especially without icing. If you are just looking to use them after the competition, I would recommend baking as per normal, and freezing the ones you won't eat right away.

The quick answer is no, you cannot freeze batter without losing most of your lift. The long answer deals with why batters rise, and what freezing will do:

1. Chemical reactions between leavening agents and acids. Baking soda reacts with acids in the batter (baking powder is a combination of a baking soda and a powdered acid) to form carbon dioxide bubbles. This chemical reaction begins immediately as soon as the ingredients are mixed, when you bake the batter the CO2 gets trapped in the sponge. Even though the reaction works slowly at low temperatures if you refrigerate or freeze it you will still lose all the lift from this reaction
2. Air from whipped ingredients: when you cream butter and sugar, or whip egg whites until stiff you are introducing air into your batter. Air expands when heated, giving your cake lift. You have to treat air raised batters gently or you will knock out the air. Freezing is not gentle
3. Water vaporizes and expands: this is the only lift you won't lose from freezing, the water in your batter isn't going to go anywhere as long as you use a sealed container

You can do one thing to preserve your batter. If you're making batter in advance just don't add baking soda, baking powder, egg, vinegar or anything that makes the cake rise. Keep it in the refrigerator and use it within 24 hours.