For butter making, cream is concentrated to 36–44% fat. The cream is then pasteurized, in the United States usually at 185°F/85°C, a high temperature that develops a distinct cooked, custardy aroma. After cooling, the cream for cultured butter may be inoculated with lactic acid bacteria. The sweet or cultured cream is then cooled to about 40°F/5°C and “aged” at that temperature for at least eight hours so that about half of the milk fat in the globules forms solid crystals. The number and size of these crystals help determine the how quickly and completely the milk fat separates, as well as the final texture of the butter. The properly aged cream is then warmed a few degrees Fahrenheit and churned.