Patent ID: 8003828

Claim:
A method of producing reduced coenzyme Q 10 crystals on a commercial scale, which comprises crystallizing reduced coenzyme Q 10 in a solution of an alcohol and/or a ketone wherein the ratio of the alcohol and/or ketone in a solvent is at least 80 w/w %, and the crystallization concentration as expressed in terms of the weight of reduced coenzyme Q 10 based on the weight of a crystallization solvent at the time of completion of crystallization is 1 to 15 w/w %, wherein crystallization is carried by cooling or a combination of crystallization by cooling with another method of crystallization, wherein the crystallization is carried out in a deoxygenated atmosphere and under forced flowing caused by a power required for stirring per unit volume of not weaker than 0.01 kW/m 3 , and wherein the crystallization is carried out at a cooling rate of 20° C./hour or less and at a cooling temperature of 20° C./hour or less.