A study of oxidation products of free polyunsaturated fatty acids in mechanically deboned meat

Preparation of mechanically deboned meat (MDM) enables a more economical use of animal products and reduction of the amount of biological wastes. On the other hand, enhanced lipid oxidation causes concerns about safety and quality of MDM. There is no information about the actual chemical structure and possible health impact of these oxidation products. The relatively low price of MDM may cause a temptation of adulteration of comminuted meat products with MDM. Until now, no good chemical marker for the presence of MDM is known. We have investigated the chemical composition of different MDMs by LC–tandem mass-spectrometry and identified a number of free fatty acid oxidation products (oxylipins). All the MDMs studied contained significantly higher amounts of free unsaturated fatty acids and oxylipins than the corresponding hand-deboned meats (HDMs). Their concentration generally yet remarkably increased during storage of the MDMs. The highest peaks at the MS base peak chromatogram of a MDM belong to 9,10,13-trihydroxy-11-octadecenoic acid (9,10,13-THODE), the main candidate for the chemical marker of MDM and an unresolvable mixture of 13-hydroxy-9,11-octadecadienoic (13-HODE) and 9-hydroxy-11,13-octadecadienoic (9-HODE) acid. In most of the oxidized MDM samples, 9,10-dihydroxy-12-octadecenoic acid (9,10-DiHOME; LTX-diol) was observed in concentrations that may give rise to some toxicological concern.