The present invention provides a stabilization method,a preservation method and the like method of reducedcoenzyme Q10, which is useful as functional nutritive foods,specific health foods and the like. Furthermore, thepresent invention provides a method for efficientlyobtaining reduced coenzyme Q10 of high quality and by amethod suitable for a commercial production.It is possible to handle and stably preserve reducedcoenzyme Q10 under a condition that oxidation by a molecularoxygen is inhibited by contacting reduced coenzyme Q10 withan ascorbic acid and citric acid or a related compoundthereof, and thus a stabilized composition is obtained.Moreover, reduced coenzyme Q10 is converted into acrystalline state in such a condition that the formation ofoxidized coenzyme Q10 as a byproduct is minimized bycrystallizing reduced coenzyme Q10 in the presence ofascorbic acid or a related compound thereof, etc., and thusa reduced coenzyme Q10 crystal of high quality is produced.Furthermore, by successively crystallizing the generatedreduced coenzyme Q10 in the presence of ascorbic acid or arelated compound thereof after reducing oxidized coenzymeQ10 to reduced coenzyme Q10 using ascorbic acid or a relatedcompound thereof, operations are simplified and minimized,and thus reduced coenzyme Q10 of high quality is produced.
