Baking Soda Query/Surprise

[Cala Massey]

On Friday night I made up some batter for carrot cupcakes. AP flour and whole wheat pastry flour, oil and applesauce(no butter), brown sugar, grated carrots, walnuts raisins etc. the amount of flour totalled 1 1/4 cups and the leavener was 1 tsp baking soda only.

I got really fatigued(I am a new baker and the process was exhausting) and decided to refrigerate the batter until the next day. This was about 8 pm. I stored it in an airtight container.

On Saturday, I was reading a couple cookbooks and most of them said that batters with baking soda should be baked immediately upon combining the soda with the liquid and the acid, since as time passes the efficacy of the leavening agent is reduced. I panicked because I was nowhere near home.

Anyway, when I got home at around 9 pm( some 13 hrs after refrigerating the batter), I decided to go ahead and bake rather than discard the batter. As I opened the container, there was a sigh as though gases were being released(kind of like when you punch down bread dough?). There were bubbles on the surface of the batter. I used a number 20 scoop to fill the muffin cupsand proceeded to bake at 350 degrees(Note that one muffin cup was filled wih water). BTW, I baked right out of the refrigerator, just added some nuts and gave it a stir.

Get this....the cupcakes rose even more than they had previously, when I had baked cupcakes immediately after blending the batter(made this recipe once before). Why did this happen? All the research suggests that the cupacakes should have baked flat.

I hope someone can explain

Thanks,

CM

Edited May 28, 2006 by Cala Massey (log)

[kitchenmage]

Cala,

Without referring to my McGee (which would require moving, and as I was up 'til dawn midwiving kittens, I'm not moving) let me see if I can answer.

Baking soda starts to create tiny bubbles (carbon dioxide, i believe) when it contacts the acid. If it's chilled it's a fairly slow process, in my experience at least, which is then sped up in the oven. When you put the batter in the refrigerator, the miniscule bubbles formed and, as long as they weren't disturbed, stayed intact.

When you put it in the oven, the heat expands the air in each tiny air pocket--and there are more of them than right after it was mixed--and the cupcakes rise more.

btw, this works even better if you put the batter in the tin and chill that, no disturbance by portioning after bubble formation. It's sort of like bread, if you don't degas it during shaping, it has more air pockets and bakes with a more open crumb.

(now one of the pros here will come along and correct any errors/oversimplifications...and i'll be melting at the sight of a tumble of half-day old kittens)

[Cala Massey]

Thanks for your reply. I did read McGee, Cookwise and others and I am aware of what happens to the flour, leavening, air pockets etc. when the stuff goes into the oven. None of these books mention what happens to chilled batter as it relates to the leavening ability of baking soda in particular...and moreso over an extended period of refrigeration. Well, I haven't found it. Will someone please post the pages of the book where this is discussed.

Having said that, thanks kitchenimage for providing some sort of explanation but is there more to this I wonder? would this refrigeration work for all kinds of cake batter? Had I not sealed the container holding the batter, would all the CO2 have 'escaped'? what if I had brought back the dough to room temperature before baking? Hoepfully, as you say, someone wil come along to shed more light.

thanks

CM

[srhcb]

I thought kitchenimage provided a pretty good explanation too.

The only relevant recipe I could find was Bernard Clayton's for homemade soda crackers, where he specified a 1 hr - overnight rest in the refrigerator for the dough. There was no explanation why, and I've never tried it, but I've always thought it might be kind of fun to make my own soda crackers?

SB (then, some homemade Velveeta to go with!)

[Sethro]

There's actually a cake on my menu that I refridegerate the batter for upt to a week, and I had a problem with it rising too much and doming on the bottom. I have to put it back in the mixer for a few minutes just so that doesn't happen.

[JayBassin]

Just guessing here, but I suspect that the rest in the 'fridge allowed the gluten in the batter to relax, thus enabling the gas bubbles to expand more. It's true that a cold environment will slow down the reaction that generates the gas. I also think that the recipe you cited had considerably more baking soda than I would use for 1.25 cups of flour (maybe 2-3 times as much). Were the cupcakes quite browned when baked? That's a result of baking soda.

[Torrilin]

Thanks for your reply. I did read McGee, Cookwise and others and I am aware of what happens to the flour, leavening, air pockets etc. when the stuff goes into the oven. None of these books mention what happens to chilled batter as it relates to the leavening ability of baking soda in particular...and moreso over an extended period of refrigeration. Well, I haven't found it. Will someone please post the pages of the book where this is discussed.

Having said that, thanks kitchenimage for providing some sort of explanation but is there more to this I wonder? would this refrigeration work for all kinds of cake batter? Had I not sealed the container holding the batter, would all the CO2 have 'escaped'? what if I had brought back the dough to room temperature before baking? Hoepfully, as you say, someone wil come along to shed more light.

thanks

CM

←

It's pretty much exactly what kitchenimage said. The precise leavener doesn't much matter, since the reactions all produce similar end results. Baking soda reacts with acid, and like most such reactions it happens quickly at high temperatures and slowly at low temperatures. So you put the soda in with the acid, bubbles began forming, and you promptly refridgerated it. You've now got batter with manymanymany tiny pockets of carbon dioxide, and a certain amount of unreacted baking soda and acid. The existing tiny bubbles will deflate slightly, since chilling the carbon dioxide will reduce its volume (this can be derived from the ideal gas law, PV=nRT). The baking soda and acid reaction continues, forming additional small bubbles. Because *these* bubbles formed at a low temperature, they're smaller than you'd expect at room temperature. Because you held the batter for a long time at low temperature, chances are the reaction proceeded to completion *before* you portioned the batter. This is not necessarily the case with batters at room temperature.

Because of the length of time you held the batter, there was minimal risk of CO2 escaping in the fridge. The volume of leavener is small compared to the batter volume, so the total amount of CO2 in your batter is also comparatively small. This means any CO2 that tries to escape has to pass through a lot of comparatively solid material, and it's in a low energy state so this is *hard*. Because the vast majority of your CO2 bubbles were very small compared to any possible portioning device, and you were not portioning with a pressure device (like a pastry bag), there was minimal risk of breaking bubbles and forcing CO2 to escape.

Once you've portioned the batter, you have many bubbles, all much smaller than the recipe anticipates. From the ideal gas law, we can derive an equation that will relate the volume of the bubbles to the change in temperature. With room temperature batter, the change in volume will be less, and much of the reaction may happen in the oven rather than at room temperature or a low temperature. (when the reaction happens mostly in the oven, you'd expect to see very large bubbles in the finished product) So rather than having a mix of very large and small to moderate sized air bubbles, your method results in many roughly evenly sized bubbles, all of which expand readily in the oven. This produces much more even leavening, and may produce the appearance of more rising ability, even tho there were no real changes in leavening power.

Since you don't specify in your question which acid you used with baking soda, I'm not even going to attempt the exact calculations. The results will vary depending on the acid used. Wikipedia is very useful if you know the acid, since you can get the chemical formula of it, work out what the exact reaction involved is, determine the thermal properties of the equation (very important in this case), determine how much CO2 is produced etc. I'm not certain how you'd go about approximating the CO2 bubble distribution in the batter, that's a bit more chemical engineering than I've studied. The gluten may also be an issue, but I'm even more unsure how you'd model that. For normal baking results (ones not involving temperatures substantially below about 5C or above about 200C), it's probably not necessary to model the gluten behavior or CO2 bubble distribution. We can also mostly ignore the effects of steam as a leavener, since the effect in most batters will be minimal compared to that of CO2.

(I regularly make use of these kinds of estimations in baking. You can *always* slow down or speed things up based on temperature, even if you're using yeast. Yeast is just a bit less temperature shock tolerant than most chemical leaveners . Very often a slower method will produce nicer results.)

Emily