PROBLEM TO BE SOLVED: To provide a method for inhibiting isomerization as much as possible in refining fats and oils by distillation.SOLUTION: In refining the reaction fats and oils after completion of the transesterification reaction by distillation, the reaction fats and oils are added with an organic acid and purified by distillation in the acidic condition to inhibit the isomerization of the fats and oils.COPYRIGHT: (C)2002,JPO【課題】油脂を蒸留精製する際に、異性化を可及的抑制する方法を提供することを目的とする。【解決手段】油脂を蒸留精製するに際して酸性条件下で行うことにより、油脂の異性下を抑制する。