Preparation of a fat phase suited for the preparation of food compositions which contain liquid or solid particles stably dispersed in the fat phase, which preparation comprises mixing 0. The rotating plate surface facing surface of the wafer or substrate has grooves, regular patterns, and irregular patterns to enhance the cleaning efficiency. The control unit comprises a memory circuit formed by ROM or RAM which stores a transmission signal waveform and a control circuit formed by a microcomputer or DSP, for example. In addition, cell lysis efficiency is significantly improved, compared to when only heating is performed. % of an impact modifier, from 0 to 25 wt.