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

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.