Analysis of lipoxygenase nonvolatile reaction products of linoleic acid in aqueous cereal suspensions by urea extraction and gas chromatography

Publisher Website
Google Scholar
Abstract
Cereals contain lipoxygenase and small quantities of linoleic and linolenic acids. For studying the oxidation of these acids by lipoxygenase in aqueous cereal suspensions and especially in doughs of wheat flour, an extraction method was developed, providing a means of quantitative extraction of the acids and their oxidation products. A complete extraction can be obtained by using urea as a disclosing agent and a chloroform‐isopropanol mixture as the extraction solvent. For the detection of the acids and their oxidation products, some of which are formed in relatively small amounts, a gas chromatographic method was developed. After extraction, the products are first methylated and silylated; then, along with an internal standard, determined with the aid of gas liquid chromatography. This method permits the determination of mono‐, di‐, and trihydroxy acids, as well as of the ketodihydroxy and α and γ ketols.