HPLC analysis for trans-vitamin K 1 and dihydro-vitamin K 1 in margarines and margarine-like products using the C 30 stationary phase

Abstract

A C 30 column successfully separated the cis and trans isomers of vitamin K 1 in margarines, reduced-fat margarine-like products and in their ingredient oils. We also measured the compound 2′3′-dihydro-vitamin K 1, a derivative formed during hydrogenation of oils containing vitamin K 1. We compared an enzymatic procedure, currently under AOAC collaborative study for milk and infant formulas, with a more direct extraction method in analyzing margarines and margarine-like products. Both methods have good precision and were applicable to the majority of products examined. Margarines or margarine-like products identifying liquid soy-bean oil, hydrogenated soybean oil or liquid canola oil as their primary ingredients contained about 50–160 μg vitamin K 1/100 g. Blends of sunflower and soybean oils contained <50 μg vitamin K 1/100 g. Hardened or “stick” margarines contained more 2′3′-dihydro-vitamin K 1 than “soft” or “tub” products (122–285 μg/100 g vs 38–131 μg/100 g, respectively). Eight of 18 products (44%) contained 10% or more of the Reference Daily Intake for vitamin K 1 per serving. Higher-fat margarines contained more vitamin K 1 than their lower-fat counterparts.