PROBLEM TO BE SOLVED: To decrease the diffusion of odor inherent in an oil or fat in cooking and inhibit the degradation of an oil or fat under heating by using a degradation inhibitor containing a turmeric extract.SOLUTION: A rhizome of turmeric, a plant of the ginger family, is dried, pulverized, and extracted with an organic solvent, such as chloroform, methanol, hexane, ethanol, or a mixture of these solvents, thus giving the objective degradation inhibitor containing a turmeric extract. By compounding this turmeric extract and another antioxidant into an oil or fat, an excellent oil or fat composition for thermal cooking can be obtained. The inhibitor is added preferably in an amount of 0.05-1,000 ppm to a vegetable oil such as safflower oil, olive oil, cotton seed oil, rapeseed oil, corn oil, soy bean oil, or palm oil. The other antioxidant is added preferably in an amount of 100-2,000 ppm to a vegetable oil. Examples of the other antioxidant are an L-ascorbic ester, tocopherol, and extracts from natural substances.COPYRIGHT: (C)2001,JPO【課題】 揚げ物用や炒め物用に用いられる加熱調理用油脂に添加することにより、調理時の油特有の匂い立ち(油くささ)を減少させ、快適な調理を可能とし、且つ油脂自体の加熱による劣化を抑制する剤を提供する。【解決手段】 ターメリック抽出物を油脂加熱時の劣化抑制剤の有効成分として用いる。