Abstract: The invention relates to a process for controlling the solidification or crystallization of a fat or a fat-containing food, wherein the solidification or crystallization is carried out under the influence of a magnetic field. The process can be used particularly advantageously where the fat is polymorphic, for example, cocoa butter, and the magnetic field allows the fat to be produced in a particular crystalline form. Thus, a cocoa butter containing product in solid form can be produced, the cocoa butter having been formed directly from a liquid phase in crystal form VI without passing through another crystal form and without the addition of seed crystals.