Effect of menadione (vitamin K3) addition on lipid oxidation and tocopherol content in plant oils

The effect of added menadione (vitamin K3) to stored corn and wheat germ oil on the dissolution and dimerization of natural tocopherols and auto-oxidation of triacylglycerols were investigated. Samples of corn and wheat germ oils pure and with added menadione were stored at +20°C in brown and transparent glass bottles. During storage their peroxide value, changes of the content of fatty acids and dissolution of tocopherols were measured. Destruction of individual tocopherols in tested oils with added menadione stored in both dark and transparent glass bottles was greater than in these oil samples without menadione. However, the degradation of individual tocopherols was different in each oil. Addition of menadione to the both oils resulted in accelerated the process of auto-oxidation of these oils. The corn oil stored in transparent bottles was oxidized faster than the one stored in brown bottles. The pro-oxidant activity of menadione was additionally activated by light. In contrast, in the cause of germ oil, the process of auto-oxidation was very fast regardless of sort of container. Addition of menadione to the plant oils influenced the dissolution of natural tocopherols but did not influence the dimerization of tocopherols. As from the experiment, the addition of menadione to the oils decreased their nutritive value.