So, with a big help from one of my favorite books The Modern Cafe~by Franciso Migoya- Pastry Chef/Instructor at my alma matter The Culinary Institute of America I have explained butter in a way that I hope makes it a bit easier to understand.
I went a little off the subject when I got to the Laminated Dough section, But I tend to do that from time to time, so try to stay with me!!
BUTTER: Not all butters are the same.
Milk is poured into a machine called a separator. The cream rises to the top and is skimmed off and pasteurized. Some manufacturers will let it sit overnight to stabilize which controls the crystallization of the fat, which in turn determines the consistency of the butter.
The liquid that remains in the separator is skim milk. Once the heavy cream has been pasteurized and the fat has crystallized, it is transferred to a churn anywhere from 30 minutes to an hour, depending on how quickly or slowly the liquid separated from the milk solids. In the churn the solids are separated from the liquid that remains which is now called buttermilk. The resulting fat solids are now mixed to form the finished product- BUTTER.
Premium butters will contain at least 82% fat
Some butters are more elastic than others, which means they can be stretched to a certain extend before they crack. This quality is called plasticity. This does not mean spread ability like for example how easily it goes on a piece of bread I am speaking in advanced pastry terminology here, and the best way to understand what I mean by plasticity is for those of you whom have made a LAMINATED DOUGH such as Croissant Dough.
Puff Pastry Dough or Danish Pastry Dough. These doughs all require that the butter be rolled and folded in between layers of dough. The dough goes through an intense process of rolling and folding several times. In this process of rolling and stretching both the dough and the butter together, the more PLASTICITY the butter has in your roll-in, the easier time you will have achieving the delicate balance of butter consistency to dough consistency which is the main key in creating a perfect laminated dough. If the butter is too hard and tends to crack easily, so will your dough as you roll it in.
BUT, let’s stick to the most basic question I get here on the Swiss Buttercream recipe as most of you are not making laminated doughs but instead seem to be making fabulous cakes with my Swiss buttercream recipe!
“Why did my buttercream “break” or have a lot of moisture in the bowl that doesn’t seem to incorporate in?”
The lower the fat content in the butter, the higher the water content will be, thus making some problems for some people here with too much “liquid” or moisture in their buttercream. I have read some comments where people complain that their buttercream has separated, and became liquidy at the bottom. This is what I mean when I say it has “broke”.
The culprit could ver ybe a lower quality butter with a low fat content and more moisture, however the #1 reason for this seems to be that the butter was too cold!
Also, always use Unsalted butter.
Salted butter by nature has a higher moisture content, which could again be the culprit for broken pastry dreams!