Creaming Butter Without Sugar

I thought I should probably do the obvious and see what happens when I simply whip butter without any sugar present. Today I did that with "room temperature" butter and bowl, and here are the results, weight minus tare in the middle column and percent volume increase in the right column. One cup of butter in the small bowl, measuring half-cups because without the sugar there wasn't enough volume to measure a full cup.

Starting temperature: 70.0 F.

0 - 100
1 - 94 - 6.4%
2 - 89 - 12.4%
3 - 82 - 22.0%
4 - 78 - 28.2%
5 - 72 - 38.9%
6 - 69 - 45.0%
7 - 65 - 53.9%
8 - 64 - 56.3%
9 - 63 - 58.7%
10 - 61 - 64.0%
11 - 60 - 66.7%
12 - 56 - 78.6%
13 - 55 - 81.8%
14 - 52 - 92.3%
15 - 51 - 96.1%
16 - 50 - 100.0%
17 - 49 - 104.1%
18 - 47 - 112.8%
19 - 47 - 112.8%
20 - 45 - 122.2%
21 - 44 - 127.3%
22 - 44 - 127.3%
23 - 44 - 127.3%
24 - 45 - 122.2%

Final temperature: 74.5

I forgot to measure the final temperature right away after I was done, so actually it was higher than that. It was around ten minutes after I finished that I remembered to measure the final temperature.

I'm going to show the volume results without sugar next to the results with an equal number of cups of sugar present, to compare. Middle column is with one cup of butter only, right column is with one cup of butter plus one cup of sugar:

0 - 0.0% - 0.0%
1 - 6.4% - 18.2%
2 - 12.4% - 30.7%
3 - 22.0% - 40.5%
4 - 28.2% - 46.9%
5 - 38.9% - 52.1%
6 - 45.0% - 52.9%
7 - 53.9% - 56.6%
8 - 56.3% - 59.5%
9 - 58.7% - 61.5%
10 - 64.0% - 64.6%
11 - 66.7% - 60.5%
12 - 78.6% - 63.5%
13 - 81.8% - NA
...
21 - 127.3% - NA

Very interesting, I think! This is how I interpret things. Initially, the presence of sugar helps incorporate air into the butter. However, as the amount of volume increase reaches 60% or so, the presence of sugar becomes an impediment to more air becoming incorporated. At around ten minutes the air in butter alone surpasses the amount of air in butter plus sugar, and after that the air in butter alone keeps increasing until the volume has more than doubled from included air, while the butter plus sugar just can't bring any more air in.

The limit on how much air can be included seems to depend on the strength of the mixture and its weight. Sugar is denser than butter, so a mixture weighs more. The combination of increased weight and effect on strength of the mixture causes butter plus granulated sugar to max out on air content at around 64%, while butter alone maxes out at almost exactly twice the air contents of butter plus sugar's max, at about 127%.

The temperature of butter has a big effect on its strength. Both of these experiments brought the temperature of the butter to around 75 degrees. I measured 76.7 F at the completion of the experiment with sugar present. Possibly presence of sugar increases the temperature of the mixture slightly due to effects of friction, and a slightly higher temperature is contributory to the limits on how much air can be incorporated when sugar is present. If one had a goal of getting as much air into the mixture as possible, one should probably put the bowl and beaters in the refrigerator for a bit after about ten minutes, and after the butter has cooled a little continue beating, but I don't think that is a goal for cookies. I have seen warnings not to cream butter and sugar too long.

I don't think this particular experiment taught us a lot about making cookies because nearly all recipes that include butter also include sugar which is creamed with the butter. I can't think of any recipes offhand that talk about just beating the butter until it is fluffy, then add sugar or other ingredients. But there could be such recipes!

We can get one thing from this, though. Recipes do have different ratios of butter to sugar. If there is very little sugar, the butter mixture will behave a lot like my no-sugar results above - we'll have to beat longer to get the same degree of fluffiness, but the limit will be higher. And if there are more cups of sugar than there are butter, then the creaming time will be shorter but the limit on how fluffy the dough can possibly be would be lower.

Yet, we have to keep in mind that what happens to a baked cookie is key, and that may impose lower limits on the amount of air we've whipped in than the amount of sugar would impose. I still have to test that.

I wonder how adding eggs or water affects creaming volume results?