Abstract: Dry yeast S.cervisiae as raw material,dissolve it in the solution of 20% potassium hydroxide,saponify and reflux it for 2.5 h at 95℃,extract with diethyl ether,concentrate it and drop gradually it in temperature from 4℃to-7℃to get ergosterol crystal.The next step is to dissolve the crude product in the diethyl ether and to recrystalliz with gradual temperature lowering, so the crystal of the ergosterol is obtained.The yield of the ergosterol crystal is 0.69%(relative to the dry yeast),and the extract rate can achieve 62.58%.Scanning electron microscope(SEM)is employed to observe the morphology of the ergosterol and the infrared furrier spectrometer is used to record the infrared spectrum of the ergosterol.

Key words: ergosterol, yeast, extract, crystal