58 th International Congress of Meat Science and Technology, 12-17 th August 2012, Montreal, Canada IS NUTRITIONAL ENRICHMENT OF OMEGA-3 FATTY ACID IN MEAT A CONCERN FOR QUALITY DETERIORATION BY LIPID OXIDATION? Eric N. Ponnampalam 1,3 , Viv F. Burnett 1 , Sorn Norng 1 , David L. Hopkins 2 , Joe L. Jacobs 1,3 and Frank R. Dunshea 3 1 Future Farming Systems Research Division, Department of Primary Industries, Victoria, 3001, Australia; 2 NSW Department of Primary Industries, Centre for Red Meat and Sheep Development, PO Box 129, Cowra, NSW 2794, Australia; 3 Department of Agriculture and Food Systems, The University of Melbourne, Parkville, Victoria 3010, Australia. Abstract – This study investigated whether polyunsaturated fatty acids (PUFAs), mainly omega- 3 (n-3) fatty acids, is a cause of quality deterioration in meat due to lipid oxidation. Lipid oxidation was evaluated in fresh and aged meat (vacuum packaged) (M. longissimus lumborum) displayed under refrigerated conditions for 4 days. The aged meat was stored at 3°C for 4 weeks. The effect of muscle PUFAs (n-3 and omega-6 [n-6]), heme iron and vitamin E concentrations on lipid oxidation was examined using regression analysis and shingle plots. Shingle plots were used to investigate the relationship between thiobarbituric acid reactive substances and other variables by conditioning on vitamin E or vice versa. The results showed a strong positive relationship between n-3 or n-6 fatty acids or heme iron and lipid oxidation when vitamin E was below 2.95 mg/kg muscle. The data demonstrate that vitamin E concentration in muscle has a major effect on controlling lipid oxidation in muscle tissues, but n-3 fatty acids play a minor role unless the vitamin E concentration falls below 2.95 mg/kg muscle. Key Words – antioxidant status, biochemical components, meat. I. INTRODUCTION Studies conducted in humans and rodents have shown that n-3 fatty acids can reduce free radical formation and development of secondary metabolites within the circulatory system and body tissues by lowering low density lipoprotein (LDL) production, formation of inflammatory substances and oxidative stress [1,2,3]. Polyunsaturated fatty acids (PUFA), particularly omega-3 (n-3) fatty acids, have been implicated as the primary cause of lipid oxidation in meat [e.g. 4]. Understanding the interrelationship between muscle biochemical components (vitamin E, n-3 PUFA, heme iron) and their interactions with respect to lipid oxidation in muscle tissues is crucial to understanding the involvement of PUFA in lipid oxidation. This will in turn enable the tailoring of the functions of these chemical components in biological systems through nutritional management so that the integrity, nutritional value and freshness of meat are optimized. The objective of this study was to investigate the combined effect of antioxidants (vitamin E), iron (heme, nonheme) and PUFA (n-3, omega-6 (n-6) fatty acids) on lipid oxidation of muscle tissues in lambs, as a model for quality deterioration of muscle foods in domestic animals. We hypothesise that n-3 fatty acids in muscle are not the major cause for quality deterioration of muscle foods due to lipid oxidation. II. MATERIALS AND METHODS Fifty four second cross lambs (Poll Dorset × [Border Leicester × Merino]) were assigned to 18 groups based on initial liveweight (range 28.8 – 39.6 kg) and gender, and then randomly allocated to four dietary treatments. The experiment was an asymmetric split-plot design comprising four treatments: perennial pasture (PP); annual pasture plus supplement of hay (lucerne [alfalfa] and annual ryegrass) and oat grain (AP); AP and whole bruised flaxseed (APFS); AP and flaxmeal (APFM). The supplements for lambs on AP, APFS and APFM were offered as 500 g of pellets daily for the first two weeks and 700 g of pellets daily for the remaining five weeks. OXIDATIONP-98