Development of analytical procedures to study changes in the composition of meat phospholipids caused by induced oxidation.

Lipid peroxidation affects quality of meat products. The aim of this study was to develop a model system and analytical procedures for evaluating the oxidation level of meat samples, by studying the changes in meat phospholipids (PL) composition and the compounds generated by induced oxidation. Different techniques (liquid-, dry column-, accelerated solvent extraction) were investigated to identify a suitable lipid extraction system for extracting PL from bovine meat and to induce lipid oxidation by using tert-butyl hydroperoxide, 2,2'-azobis(2-amidinopropane) dihydrochloride (ABAP) or Fe(2+) and Cu(2+) salts. Accelerated solvent extraction (ASE) gave results not significantly different from the other extraction methods, but offered the advantage of being a rapid and solvent-saving procedure. The method using a silica column proved to be valid in eluting and separating the components of the phospholipidic fraction and the PL standard mixture. The analytical techniques used to analyse oxidation products of PL included GC-FID, HPLC with corona charged aerosol detector (CAD), MDA determination and the spectrophotometric measurement of peroxide levels (PxL). By means of CAD, PL were quantified and their concentration in the lipid extract was 0.98%+/-0.17 (w/w+/-SD, n=10). The oxidation method induced by ABAP proved to be fast and did not produce any artifacts. Three oxidation times were monitored (0, 90 and 180 min). The oxidation levels after 180 min correlated with a significant increase in the peroxide levels PxL (+71%), MDA (+29%) and aldehydes (+75%), whereas a decrease or even total disappearance of some unsaturated fatty acids was observed. The results obtained demonstrate that the model used in this work is useful for studying oxidation of meat phospholipids. Also, the use of the innovative detector CAD proved to be a good complementary technique in the investigation of lipids.