Oxidation of free and esterified linoleic and linolenic acids in bread doughs by wheat and soya lipoxygenases

Abstract

Lipids containing ¹⁴C‐labelled linoleic and linolenic acids were added to flour which was then made into bread doughs with or without 2% enzyme‐active soya flour. The ¹⁴C‐labelled lipids and their oxidation products were analysed as intact lipids or as ¹⁴C fatty acid methyl esters by thin‐layer chromatography. In the control doughs wheat lipoxygenase oxidised free fatty acids and monoglycerides. In doughs containing soya flour, steryl esters, triglycerides, diglycerides, mono‐galactosyl diglycerides, digalactosyl diglycerides and phosphatidyl choline were also oxidised, and the oxidation of these lipids is attributed to soya lipoxygenase.