Creaming Butter and Sugar - Large vs. Small Bowl

I mentioned this great page on creaming butter and sugar sometime last week. Thanks to the author, Sarah Phillips! The last few days I've been doing some experiments with creaming butter and sugar.

To get a handle on what's going on, I need a way to measure how much the creaming process has progressed. The key to doing that easily is based on the amount of air that gets incorporated into the butter-sugar mixture. If air is incorporated, the volume increases. It's increasing because of air added. Air weighs nothing, for all practical purposes. If you weigh a fixed volume of butter, and then weigh the same fixed volume of butter mixed with air, which will weigh less? Answer: the butter mixed with air.

So, here's how a single experiment would go:

1. Slowly mix a measured amount of sugar with a measured amount of butter. "Slowly" means slowly and gently enough that no air gets whipped into the butter. Mashing butter and sugar together in the bowl with a spatula until all the sugar is mixed in with the butter works great for that.
2. Weigh one level cup of the mixed butter and sugar and record the weight.
3. Beat the mixed butter and sugar for one minute.
4. Weigh one level cup of the mixed butter and sugar and record the weight.
5. Repeat steps 3 and 4 until the weight stops changing.

This is very easy and anybody can do this with their own mixer. And here's a side comment to readers - your mileage will vary. In other words, I'll get certain numbers, but if you do it in your own mixer, you'll get different numbers. The results depend on the size and shape of your mixer bowl, the rotation speed of the beaters, the design of the beaters, how far apart the beaters are (if you have two of them), and how high up the butter and sugar mixture comes on your beaters. The numbers will be different - but you can use the numbers from your own mixer in exactly the same way I am to figure out what you should do in your own kitchen. Don't be scared off by any calculations here. I'm throwing them in because I think they are interesting, but you can pretty much dispense with all the calculations and just look at the measurements. All you need is a measuring cup and a kitchen scale that measures in grams, and a little bit of butter and sugar that you might throw out unless you have a recipe to use them in.

EXPERIMENT 1: large bowl, 2c butter + 2c granulated sugar, all room temp

What I expected to see the first time I tried it, based on the Web page I found, was a steady decrease in the weight over time, then a leveling off, and finally a reversal, i.e. eventually the weight would start to increase instead of decrease. Things worked great, and the first time I did the experiment it seemed like I got exactly what I expected. Here are the numbers from my first experiment - the numbers on the left are how many minutes passed, with '0' being the weight before I started mixing at creaming speed, and the numbers on the right are the combined weights of butter-sugar and the measuring cup in grams:

0 - 298
1 - 270
2 - 261
3 - 248
4 - 237
5 - 234
6 - 233
7 - 240

So I thought that sometime after six minutes the weight started to increase because the butter was getting too warm like the Web site described, and I stopped beating and measuring at that point.

That first experiment, I used my large mixer bowl and creamed together two cups of butter and two cups of sugar, with everything starting at room temperature.

To see what's actually happening for analytical purposes, I have to subtract out the weight of the cup, which is 54 grams:

0 - 244
1 - 216
2 - 207
3 - 194
4 - 183
5 - 180
6 - 179
7 - 186

The point of creaming butter and sugar is to increase the amount of air in the mixture, and that's going to be in direct proportion to the increase in volume - which is in inverse proportion to the decrease in weight. For example, suppose the initial weight is 200g, and after 3 minutes it goes down to 150g. You can set up a formula:

new weight = old weight x (150/200) = old weight x 0.75

and that means

new volume = old volume x (200/150) = old volume x 1.33

or in other words, a 33% increase in volume.

So I can use that formula to calculate the increase in volume as beating goes on. Using that first set of numbers (after subtracting the weight of the cup), I calculate these numbers as the volumes, with the initial volume being 1.000 cup:

0 - 1.000
1 - 1.129
2 - 1.179
3 - 1.258
4 - 1.333
5 - 1.356
6 - 1.363
7 - 1.290

What this tells me is that, beating intermittently by minutes and then stopping briefly to measure, starting with ingredients and bowl at room temperature and beating 2c butter and 2c granulated sugar in my large bowl, the volume is as large as it's going to get after 6 minutes.

I didn't have to do all the calculations to get that answer - all I had to do was look at the decreasing numbers, and see where the weight was the lowest. That was when the total weight of a mixture was 233g, including the weight of the cup. I just did the calculations here so we could see exactly how much the volume increased - 36.3%.

Obviously I'm not measuring to that many significant digits, so saying "36.3%" is overdoing the conclusion. :-) But it's useful to see how the numbers are coming out, because there is obviously a steady decrease in weight and calculated increase in volume for the first 6 minutes.

An increase in volume of 36% because of air whipped into the butter is quite a lot, isn't it?

EXPERIMENT 2: small bowl, 1c butter + 1c granulated sugar, all room temp

Well, I didn't immediately do the same experiment again - I moved on to something else. Next time I used my small bowl, with one cup each of butter and granulated sugar, again everything at room temperature. Here were my weights - I'm going to subtract the weight of the cup (always the same cup for these experiments, so always 54g) and give the total weight minus the tare - i.e. the weight of one cup of the butter plus sugar alone - in a third column:

0 - 314 - 260
1 - 274 - 220
2 - 253 - 199
3 - 239 - 185
4 - 231 - 177
5 - 225 - 171
6 - 224 - 170
7 - 220 - 166
8 - 217 - 163
9 - 215 - 161
10- 212 - 158
11- 216 - 162
12- 213 - 159

Interesting! So the large bowl weight measurements reversed at 7 minutes, but in the small bowl the weight continued to decrease until 11 minutes. And then after that first increase, it went back down again. And the maximum volume increase in the small bowl was at 10 minutes, with the amount of increase being 64.6%! Compare that to 36% in the large bowl. That's a big difference!

And 64.6% volume increase is huge, isn't it?

Immediately a question comes up - did I quit taking measurements too soon in the large mixer? The weight definitely increased, but in the small bowl it increased at 11 minutes but then went back down. Does the small bowl really do that much of a better job at creaming butter and sugar? If it does, that's important to know.

Here's a consideration with the small bowl - the diameter of the bowl isn't that much greater than the width of the two beaters together, so in the small bowl any piece of butter is being constantly whipped. The diameter of the large bowl is way bigger than the width of the two beaters, and as the bowl spins, much of the time a particular piece of butter is not being whipped. So I'd actually expect creaming to take a lot longer in the large bowl. I would expect the butter could be creamed equally in either bowl - that is, the volume would increase equally in either bowl - but just to take longer in the large bowl.

Notice the starting weight was higher in the smaller bowl. What's that about? Same ingredients - why a different weight for one cup?

Actually, I didn't do the same thing to mix the butter and sugar together in experiments 1 and 2. I said mixing together with a spatula before the start works great. Actually, I concluded it works best for this - but that's not what I did for experiment 1. For the first experiment, I just put the mixer at very slow speed and mixed them with the mixer for two minutes. The result - the weight I measured was only 298g versus 314g when mixed by hand with a spatula. Even the slow mixing in the mixer mixed some air into the butter. To calculate percent volume increase from the start, I need to start with the weight when no air is included, so the volume increases I measured from the first experiment aren't really valid. In my subsequent experiments with these ingredients the starting weights were always from 310 to 314g so I think all the later volume calculations are pretty valid, but that first experiment is a little goofed up.

EXPERIMENT 3: large bowl, 2c butter + 2c granulated sugar, all room temp

So, I repeated experiment 1, again with 2c sugar and 2c butter in the large bowl, everything at room temperature, and came up with these results:

minutes - with cup - without cup
0 - 310 - 256
1 - 284 - 230
2 - 262 - 208
3 - 248 - 194
4 - 239 - 185
5 - 233 - 179
6 - 237 - 183
7 - 235 - 181
8 - 235 - 181
9 - 229 - 175
10 - 230 - 176
11 - 227 - 173
12 - 221 - 167
13 - 223 - 169
14 - 219 - 165
15 - 216 - 162
16 - 216 - 162
17 - 216 - 162
18 - 217 - 163
19 - 212 - 158
20 - 212 - 158
21 - 210 - 156
22 - 210 - 156

Good thing I repeated that!

First, notice that the direction of weight change again reversed after a few minutes. In the first experiment, it reversed after 6 minutes, and then I stopped. In the repeat, it reversed again but after 5 minutes, but after that it continued downwards.

Now, there is a possible source of error in the weight measurements. I'm packing the butter into the cup by scooping up a bit at a time with the spatula and scraping it into the cup. It takes three or four scoops to fill over the top. If I accidentally leave an air pocket in the cup because I don't pack it well enough, the weight is too light - and I can't tell when that happens. So here, the weight at 5 minutes is lighter than 4 or 6 minutes. Was it really lighter, or did I just have an air pocket there? I don't know. And so we don't know if the weight actually reversed at 6 minutes. If I did it several more times we'd know for sure. Frankly, I don't care enough to do it several more times. I think I get a good enough idea from this without killing myself with repeat experiments - life is too short! I can get enough from these numbers.

We can see that the longer I beat the butter, the more air I whipped into it. If I beat it another 20 minutes, would it just keep getting more and more air in it? In 20 minutes, I didn't see the volume start to decrease, it just kept increasing. This is not what I expected based on what the other Web site said. But THAT is why I'm doing these experiments! Facts don't lie, and I only care about what happens with my equipment.

Not that the Web site was incorrect. I just now took another look, and saw on a different page of the site that the author says creaming too long is bad because the butter gets too much air in it and it collapses in the oven. OK, that makes sense. It actually matches what I saw. And I did notice that butter I creamed for a long time became "gloppy", indicating something had changed. Basically it didn't have enough strength to support its own weight very well at that point, even at room temperature. But though gloppy, it was still retaining the air at that temperature, as determined by the weight of a level cup of the mixture.

I'm going to add one more column to that data. Here, the right-most column is the change in weight for that measurement from the previous weight measurement:

0 - 310 - 256
1 - 284 - 230 - (26)
2 - 262 - 208 - (22)
3 - 248 - 194 - (14)
4 - 239 - 185 - (9)
5 - 233 - 179 - (6)
6 - 237 - 183 - (-4)
7 - 235 - 181 - (2)
8 - 235 - 181 - (0)
9 - 229 - 175 - (6)
10 - 230 - 176 - (-1)
11 - 227 - 173 - (3)
12 - 221 - 167 - (6)
13 - 223 - 169 - (-2)
14 - 219 - 165 - (4)
15 - 216 - 162 - (3)
16 - 216 - 162 - (0)
17 - 216 - 162 - (0)
18 - 217 - 163 - (-1)
19 - 212 - 158 - (5)
20 - 212 - 158 - (0)
21 - 210 - 156 - (2)
22 - 210 - 156 - (0)

Yeah, I know, I used positive numbers in that last column where I should have used negative and vice versa. You get it.

From this it's clear that you have big changes at first, and then the changes happen more and more slowly. When you cream butter and sugar, is the goal to get as much air as possible into it? If so, you have to cream for quite a while. If not, you can quit after a while and it will be almost as much as you'll get even if you go a lot longer. Here's the data, with the right-most column showing the amount of volume increase in percent:

0 - 310 - 256
1 - 284 - 230 - 11.3%
2 - 262 - 208 - 23.1%
3 - 248 - 194 - 33.0%
4 - 239 - 185 - 38.4%
5 - 233 - 179 - 43.0%
6 - 237 - 183 - 39.9%
7 - 235 - 181 - 41.4%
8 - 235 - 181 - 41.4%
9 - 229 - 175 - 46.3%
10 - 230 - 176 - 45.5%
11 - 227 - 173 - 48.0%
12 - 221 - 167 - 53.3%
13 - 223 - 169 - 51.5%
14 - 219 - 165 - 55.1%
15 - 216 - 162 - 58.0%
16 - 216 - 162 - 58.0%
17 - 216 - 162 - 58.0%
18 - 217 - 163 - 57.1%
19 - 212 - 158 - 62.0%
20 - 212 - 158 - 62.0%
21 - 210 - 156 - 64.1%
22 - 210 - 156 - 64.1%

I'm just going to select certain numbers from this and instead of listing the exact volume calculation, list the average volume calculation for a time, the previous minute, and the next minute, which evens out the errors in measurement and experimental variation a little bit. So here's percent volume increase after various times:

5 min: 40.4%
10 min: 46.6% (an additional 6.2%)
15 min: 57.0% (an additional 10.4%)
20 min: 62.7% (an additional 5.7%)

So if you cream for five minutes, I get 40% volume increase. For at least the next twenty minutes I keep getting additional volume increase, but it's not anything like as much as I got in the first 5 minutes.

Next I look back at results from the small bowl. I don't know what the maximum increase I might have gotten in large bowl was, but the maximum I saw in the small bowl before the increase seemed to stop was 64.6%. Hey, that's basically exactly the same maximum I saw in the large bowl before I finally quit! Excellent. But here's the interesting thing - it only took me ten minutes to get that in the small bowl (with half the volume of ingredients), but twenty-two minutes in the large bowl.

That's pretty important to know.

Now lets look at the results from the first time I did the experiment compared to the repeat, for as many minutes as I did collect measurements the first time:

0 - 298 - 310
1 - 270 - 284
2 - 261 - 262
3 - 248 - 248
4 - 237 - 239
5 - 234 - 233
6 - 233 - 237
7 - 240 - 235

I already mentioned that I mixed the butter and sugar differently at the start for the two experiments. That's why weights at times 0 and 1 minute are so different. But look at 2 minutes and beyond - the numbers are almost identical! With some variance around 6-7 minutes, for some reason. So no matter how I start, the volume increase is about the same a couple of minutes into the mixing. Is that good news? You bet! That's excellent. I'm trying to learn how to make cookies reproducibly. If I do the same thing twice in a row, I'd better get the same results! This shows if I cream butter and sugar for a certain amount of time, I'm going to get a certain amount of volume increase. It will depend on certain variables, but there don't seem to be any random mystery variables that I can't control.

If this were "real science" I'd be doing this a whole bunch of times and calculate a standard deviation in volume increase after various times, but I feel fine dispensing with that, and I bet you do, too. :-) I think I'm learning what I wanted to learn.

I haven't drawn any conclusions about how long to cream butter and sugar at this point. For that, I need to see the effect of different times on cookies, and I have more creaming experiments to do and report first. For one thing, when I cream butter and sugar for a real recipe, I don't turn the mixer off and on constantly during the process, and pat the butter down into a cup several times along the way. I already checked once, and I know it affects the results, I assume in a systematic way. Before I would draw any solid conclusions on how long I should cream butter and sugar, I have to get some measurements of what happens when you just start up your mixer and let it go straight through to the defined time endpoint. That, unfortunately, is more expensive because it uses up a lot of ingredients, but I'll see what I can do to get useful data.