There is provided a method for preserving the temperature of a liquid, the method characterized in including a step for adding an edible-roasting-oil-containing oil to a liquid containing at least 80% by mass of water so that the amount of the edible roasting oil per square centimeter of the area of the surface of the liquid is at least 0.0007 g, the color level of the oil including the edible roasting oil (Y+10×R+10×B) as expressed by the formula Y+10×R+10×B is at least 20 (Y, R and B represent, respectively, the Y value (yellow slide value), R value (red slide value), and B value (blue slide value) measured with a Lovibond colorimeter (cell: 25.4 mm))本發明係提供一種液體之保溫方法，其特徵為包含在含80質量%以上之水的液體中，以對每1cm2前述液體的液面面積而言烘焙食用油為0.0007g以上之量的方式添加含烘焙食用油之油的步驟，前述含烘焙食用油之油以下述式(1)表示的色值(Y+10×R+10×B)值為20以上，Y+10×R+10×B．．．式(1)此處，Y、R、B係表示以洛維邦(Lovibond)比色計(25.4mm單元)測定的Y值(黃色載片之值)、R值(紅色載片之值)、B值(藍色載片之值)。
