Cocoa butter is the naturally occurring fat in cocoa beans. It is extracted from chocolate liquor by pressing and is generally filtered and deodorized before use. The function of cocoa butter in chocolate is to suspend and lubricate the cacao and sugar particles. Cocoa butter lowers the viscosity of melted chocolate but does not itself significantly contribute to chocolate flavor, having little flavor of its own. Cocoa butter has several unique qualities that make it a very desirable fat:
Cocoa butter has a narrow melting range that is just below normal human body temperature. It tends to stay hard until it is very close to body temperature, and then it melts rapidly, carrying and releasing flavors on the palate.
Cocoa butter sets to a brittle consistency at normal room temperature. If cocoa butter were not brittle, chocolate would not have its characteristic snap.
Cocoa butter contracts significantly upon setting. It is the contraction of cocoa butter as it crystallizes that makes it possible for the confectioner to release chocolate easily from molds once it is set.