Dihydrovitamin K-1 in oils and margarines

In the present study the vitamin K-1 and 2',3'-dihydrovitamin K-1 contents of several crude vegetable oils, partially hydrogenated oils used as raw ma terials in the margarine industry and margarines were analysed with a high- performance liquid chromatographic (HPLC) method. Prior to quantification b y reverse-phase HPLC with an electrochemical (EC) detector, hexane extracts of samples were purified by straight-phase semipreparative HPLC. Menaquino ne-4 (MK-4) was used as an internal standard. All hydrogenated oils (rapese ed, soybean and mixture of rapeseed and palm) contained considerable amount s of 2',3'-dihydrovitamin K-1, which accounted for approximately 60% of the sum of 2',3'-dihydrovitamin K-1 and vitamin K-1; however, among the margar ines analysed 2',3'-dihydrovitamin K-1 was found only in hard margarines me ant for the baking industry. The proportion of 2',3'-dihydrovitamin K-1 in these products was 25% of the total. The appearance of 2',3'-dihydrovitamin K-1 among the samples analysed correlated with that of Irans fatty acids. During recent years the Finnish margarine industry has focused on reducing the amount of trans fatty acids in soft margarines. It was concluded that b ecause of these changes in the manufacturing process, 2',3'-dihydrovitamin K-1 plays no significant role in vitamin K nutrition in Finland. (C) 1998 E lsevier Science Ltd. All rights reserved.