In general, butter is made by mixing heavy cream until the butterfat comes together and separates from the buttermilk. The buttermilk is drained off and the remaining butter is shaped and ready to eat.
Factory Made Butter
First, large amounts of raw milk are pumped directly from the delivery truck into a ” separator.” A separator is a machine that spins and separates the fat in the milk from the rest of the liquid. The fat is called ‘butter cream’ and the remaining milk is processed to make skim milk. The butter cream is about 38% fat.
The butter cream is stored in a bulk tank where it is stirred to maintain consistency while it is pasteurized and aged for 24 hours. The butter cream then goes into a churner where it is spun very quickly, at a speed similar to that of a clothes dryer. The fat comes together to form small butter clumps.
The excess liquid, buttermilk, is drained into a separate container for other uses. Flavor is added and then churned further until it comes together and becomes smooth and creamy. The butter is then shaped, packaged, and shipped. Store-bought butter can last up to three months in the fridge.
Homemade butter is made similarly to that in a factory, just on a much smaller scale.
Heavy cream is whipped, which can be done with a stand mixer, hand mixer, or blender (though before the invention of electricity this was done with a butter churn). Then, once the butter begins to clump and come together the buttermilk is poured off.
The butter solids are rinsed with cold water in a bowl. Next, salt and any other flavorings are added and the butter clumps are mushed together and the butter is shaped into a ball.
Lastly, the butter is rinsed once more and set on a muslin cloth to allow any remaining water to drain. Then the butter can be chilled and eaten. Homemade butter only lasts 3-5 days.
American, European, and Irish Butter
European butter is churned longer and has higher butterfat than American butter. Because it has higher butterfat European butter has more fat and less water. This results in it having a richer flavor, a softer texture, and bright yellow color. European butter is also easier to spread than American butter due to its softer texture.
European butter is usually unsalted and cultured while Irish butter is often salted and uncultured. The bright yellow color is considered to be a hallmark of pure Irish butter. Cultured butter is made from cream that has been fermented before it is churned into butter.