Effect of electron-beam irradiation on cholesterol oxide formation in different ready-to-eat foods

A study of the formation of 1 1 Cholesterol oxidation products (COPs). cholesterol oxidation products (COPs) has been carried out in four 2 2 Ready-to-eat (RTE). ready-to-eat (RTE) foods (cooked ham, Spanish Serrano ham, minced beef, and soft cheese). The samples were previously treated with electron-beam irradiation between 1 and 8 kGy. Three COPs, 25-hydroxycholesterol, 7-ketocholesterol and 6-ketocholestanol, were extracted together with the lipid fraction using chloroform. Then, COPs were isolated by sample clean up using 3 3 Solid phase extraction (SPE). solid phase extraction (SPE) and were analyzed by 4 4 High performance liquid chromatography with ultraviolet detection (HPLC-UV). high performance liquid chromatography with ultraviolet detection (HPLC-UV). Method validation was established by precision and recovery studies. Results showed that non-irradiated cheese and cooked ham samples did not contain COPs. In general, an increase in COP content was observed in all cases when the irradiation dose increased, although this increase was not linear. The 6-keto COP was not detected in any of the RTE food samples studied regardless of the irradiation dose. Nowadays, changes in dietary habits have produced an important increase in consumption of prepared foods thus increasing microbiological contamination risks; consequently, it is necessary to apply easy methods, able to be implanted in industrial production lines, and which eliminate potential contaminants and enhance shelf life. The application of E-beam irradiation to vacuum packed ready-to-eat (RTE) food of animal origin could be a useful technique for sanitization purposes; besides, it is a clean, rapid and environmentally friendly treatment. During this treatment cholesterol oxide products (COPs) may be formed. They have received considerable attention in recent years because of their biological activity which has been associated with human diseases, such as the inhibition of cholesterol biosynthesis, atherosclerosis, changes in membrane properties, cytotoxicity, mutagenesis and carcinogenesis. Therefore, COP analysis in food samples of animal origin is of great interest. In this work, an increase in the 25-OH and 7-keto COP content has been detected after E-beam irradiation with doses from 1 to 8 kGy, which is in the upper accepted limit in other foods, but final COP concentrations found in the foodstuffs studied here were at least one order of magnitude lower than those which produce toxic effec