Abstract: An edible oil or fat improved in oxidative stability and suppressed in the development of off flavor is obtained without impairment of high physiological functions inherent to highly-unsaturated fatty acids. To obtain the edible oil or fat, a specific polyunsaturated fatty acid-base oil or a particular fat and saturated fatty acid-base oil or fat are mixed and subjected to an interesterification reaction so that fatty acids are caused to bond at random on glycerol skeletons of the oil or fat to achieve the following properties:(a) the content of polyunsaturated fatty acids of at least three unsaturated bonds per molecule in fatty acid residual groups: 5 to 30%,(b) the content of saturated fatty acids free of any unsaturated bond: 50 to 80%,(c) iodine value: at least 35, and(d) melting point: 35.degree. C. or higher.

Abstract: Lactose containing physiologically-active sialic acids can be obtained by isolating and recovering the sialic acids together with lactose from a permeate or deproteinization solution obtained by ultrafiltration or heat treatment of whey or skim milk. The sialic acids-containing lactose is useful as an effective ingredient for foods, drugs, feeds, etc.