Chocolate Chip Cookie Chemistry

December 9, 2009 12:02 AM

I'm baking chocolate chip cookies and after looking at some recipes, I realized that they all use baking soda (not baking powder) as the leavening agent. The explanation is that baking soda interacts with the acids in the chocolate to produce the leavening CO2. My question is this: Can I freeze my baking soda leavened dough? Can I leave it in the fridge until I'm ready to bake?

The chemistry suggests the answer is no, because the reaction between the baking soda and the chocolate starts immediately, and so the dough needs to baked right away. But there are plenty of people who freeze chocolate chip cookie dough for later use. Is there something I don't understand about the baking chemistry? Or are people who are taking the dough out of their freezer just eating unleavened cookie-pucks?

posted by ACF to Food & Drink (17 answers total)

I freeze my baking-soda chocolate chip cookie dough all the time. The cookies come out great.

Actually, I usually stick the dough in the fridge and then forget about it for a few days before freezing. The cookies still come out great.

Don't worry, I say -- make your cookies and be happy!
posted by wyzewoman at 12:06 AM on December 9, 2009

Best answer: Baking soda also produces CO2 if you simply heat it (thermal decomposition). Depending on how acidic the cookie dough is (I'd guess not very), this might be the main mechanism, in which case as long as the dough is kept reasonably cool it should be ok leavening-wise.
posted by hattifattener at 12:24 AM on December 9, 2009

Huh?

I can't possibly imagine there's enough surface area in the chips to impact the chemistry of the cookies so substantially—we've made chipless cookies in the same batch as those with chips and they've turned out the same. But, you know, chipless. Don't know about how leavened they need to be at the point of refrigerating, but I do know that Alton Brown talked about it some in the episode Chips for Sister Marsha.
posted by disillusioned at 12:52 AM on December 9, 2009

I don't know any of the actual science behind it, but I have frozen and refrigerated my chocolate chip cookie dough (made with baking soda) many times, and have never had a problem. Now you have me wondering, however, why blooming isn't an issue with the chocolate chips. For those who don't know, when chocolate is refrigerated and turns white it's because the cocoa butter (and in some case the sugar) separates, rises to the surfaces, and recrystalizes. That's called blooming. It's unsightly (people often think it looks "old"), but it doesn't change the taste. It's never happened to my chocolate chips though, and I cannot think of any reason why it wouldn't.
posted by katemcd at 4:08 AM on December 9, 2009

hattifattener has it. The baking soda acts as a raising agent when it decomposes during baking, not because of the acids in the chocolate. (If you omit the chocolate chips, the recipe still works.) So you can definitely chill (or freeze) the dough without affecting the quality of the cookies. I've done this many times. (Usually I do it so I can make a batch of dough and then bake a few cookies per day over the next few days. No stale cookies!)

katecmd, blooming is typically caused by the chocolate being kept too warm, not too cold, although sometimes the bloom isn't visible until the chocolate is re-chilled.
posted by buxtonbluecat at 4:55 AM on December 9, 2009

The explanation about the chocolate is wrong (or at least incomplete enough to be considered wrong). Baking powder is also called double acting baking powder because it leavens in two ways. The first is a reaction between an acid and the baking soda in the baking powder, but the key is that a powdered acid salt is already part of the baking powder. The reaction is started when liquid is added, not something else specifically acidic. The liquid dissolves the baking soda and acid salt in the baking powder and a leavening reaction starts. (Indeed, baking powder is probably used in these recipes because there is no explicitly acidic ingredient in the batter.) The double leavening occurs with the addition of heat during cooking.
posted by OmieWise at 5:13 AM on December 9, 2009

This nytimes article explores "The Perfect Chocolate Chip recipe" where the dough is left to rest for 12hr, 24hr and 36 hours before baking. Results? Alleged yumminess with different flavours coming into play as the dough rested.
posted by toddje at 5:31 AM on December 9, 2009 [1 favorite]

Another datapoint: I tried the recipe that toddje cites, and even cooked some cookies after 24 hours in the fridge and some at 48, and the ones that had chilled longer were much better.

So chill away.
posted by Aizkolari at 5:46 AM on December 9, 2009

I agree that it seems doubtful that whole chips would contribute enough acid. But molasses is also acidic, which would make the brown sugar acidic and these recipes typically have a lot of brown sugar.
posted by smackfu at 5:50 AM on December 9, 2009

Chiming in with everyone else. At our house we like the taste of freshly baked, but we don't eat the cookies fast enough before they grow stale (crazy, right?) so I only bake a third and store the rest of the dough in log shape wrapped in wax paper-- one third in the refrigerator for baking the following week, one third in the freezer for baking in two weeks. They still puff up when baked in the oven.

I have noticed a slight difference between freshly-made-baked, and chilled-then-baked-- I put that down to the "double action" meaning that the freshly made baked puff up slightly more, but just slightly. The difference is more noticeable in oatmeal cookies with the refrigerated oatmeal cookies being slightly heavier and chewier.
posted by Secret Life of Gravy at 6:33 AM on December 9, 2009

I work in a bakery, and we make cookie dough weekly, and store it in logs in the fridge. Perfect every time.
posted by bzbb at 8:20 AM on December 9, 2009

Response by poster: Got it. The CO2 reaction is not from the addition of acid (AKA chocolate), but the addition of heat, thus freezing/refrigeration preserves the leavening action of baking soda. Good to know! Thank you for straightening me out here...
posted by ACF at 10:42 AM on December 9, 2009

Freezing is fine. Just wrap tightly to prevent freezer burn, use within 3 months or so.

Refrigeration is great! The flour gelatinizes and you get a much better cookie.
posted by dirtynumbangelboy at 11:07 AM on December 9, 2009

Indeed, baking powder is probably used in these recipes because there is no explicitly acidic ingredient in the batter.

Baking powder isn't used. It's baking soda. But, regardless, the point about heat still stands, so hey.
posted by redfoxtail at 11:45 AM on December 9, 2009

Baking powder isn't used. It's baking soda. But, regardless, the point about heat still stands, so hey.

Right, oops. I've been making too many powder leavened pancakes. Sorry for the mixup.
posted by OmieWise at 1:54 PM on December 9, 2009

I make double recipes of the NYTimes recipe linked above, let them rest for 72 hours, then portion and freeze them. Amazing chocolate chip cookies whenver I want! No leavening problems!
posted by joshuaconner at 7:25 PM on December 9, 2009

Also, when it comes to chemistry in general, the colder the situation is, the slower the reaction goes. While some of the reactions involving the baking soda might start immediately, if you're keeping it at such cold temps it won't get far enough to make a difference.
posted by mismatched at 7:32 PM on December 9, 2009