PROBLEM TO BE SOLVED: To suggest an indicator for appropriately and rapidly evaluating degradation of frying oil and to provide a method for evaluating degradation of frying oil using the indicator.SOLUTION: A first method of the present invention is a method for evaluating degradation of frying oil in which the 3-methyl-2, 4-nonane dione in frying oil is used as an indicator of degradation of the frying oil, the frying oil containing soybean-derived fat in 20-100% by mass. A second method of the present application is a method for selecting frying oil which is difficult to become degraded, the method including the steps of: (i) heating at least two different types of frying oils containing soybean-derived fat in 20-100% by mass, under at least one condition selected from temperatures of 150-220°C and 5-80 hours (ii) measuring the contents of the 3-methyl-2, 4-nonane dione in the frying oils after heating and (iii) comparing the contents of the 3-methyl-2, 4-nonane dione and determining the frying oil which contains the 3-methyl-2, 4-nonane dione in the smaller amount to be the frying oil which is more difficult to become degraded.SELECTED DRAWING: NoneCOPYRIGHT: (C)2018,JPO&INPIT【課題】 フライ油の劣化を適切、かつ、迅速に評価するための指標を提案し、当該指標を用いたフライ油の劣化の評価方法を提供することを目的とする。【解決手段】 本発明の第一の方法は、大豆由来の油脂を20~100質量%含むフライ油であって、前記フライ油中の3-メチル-2,4-ノナンジオンを前記フライ油の劣化指標として使用することを特徴とする、フライ油の劣化の評価方法である。また、本発明の第二の方法は、劣化しにくいフライ油の選別方法であって、大豆由来の油脂を20~100質量%含む、2以上の異なるフライ油を、(i)150~220℃、5~80時間から選ばれる少なくともひとつの条件で加熱し、(ii)加熱後の前記フライ油中の3-メチル-2,4-ノナンジオンの含有量を測定し、(iii)3-メチル-2,4-ノナンジオンの前記含有量を比較し、3-メチル-2,4-ノナンジオンの含有量の少ない前記フライ油を2以上の異なる前記フライ油の中で劣化しにくいフライ油であるとする、前記選別方法である。【選択図】なし
