Butter is a fatty emulsion produced by churning cream until it reaches a semi-solid state. It contains at least 80% milk fat. It is a versatile fat, used as an ingredient in sweet and savoury foods, as a spread and as a garnish either as is or mixed with any of a number of ingredients such as herbs, crayfish, anchovies and so on. It melts to a liquid form at about 98ºF (38ºC) and reaches the smoking point at 260ºF (127ºC). In the United States butter is labelled according to its quality, defined by a score. The finest is AA (93 score), A (92 score), B (90 score) and C (89 score). It also describes a process of buttering a pan by wiping it with a butter paper or using a brush to spread around melted butter. It also refers to a sweetened fruit purée.