RESULTS

1. RESULTS INTRODUCTION OBJECTIVES CONCLUSION ABSTRACT MATERIALS AND METHODS Storage Stability of Omega-3-enhanced Rainbow Trout (Oncorhynchus mykiss): 1 Refrigerated Storage Temperature Y. C. Chen, J. Nguyen, K. Semmens, S. Beamer, and J. Jaczynski West Virginia University, Animal & Veterinary Sciences Regardless of packaging method, the highest (P<0.05) fat content in fillets was observed in basal diet group, followed by basal diet + 15% flaxseed oil (FO) + 1500ppm alpha-tocopheryl acetate (α-TA), basal diet + 15% FO, and basal diet + 1500ppm α-TA for 12-day storage. No interaction (P>0.05) for lipid oxidation and alpha-tocopherol content between FO and α-TA was observed. Although FO decreased (P<0.05) alpha-tocopherol content and increased TBARS values, higher (P<0.05) alpha-tocopherol content was only determined in α-TA group for a 12-day storage. Overall, regardless of FO and α-TA, a vacuumed package kept the higher (P<0.05) alpha-tocopherol content and lowered (P<0.05) TBARS values. In the fatty acid profile (FAP), interactions (P<0.05) between FO and α-TA were observed. Regardless of packaging method, α-TA addition decreased (P<0.05) proportion of saturated FA and Docosahexaenoic acid (DHA), as well as increased (P>0.05) proportions of unsaturated FA, total ω-3 FA, α-linolenic acid, and Eicosapentaenoic acid (EPA) in the fillet’s lipid when FO was present in the fish diet. Table 1. Moisture (%), fat (%), alpha-tocopherol content, and TBARS of trout fillets as affected by supplementing trout with FO and α-TA FO: flaxseed oil; α-TA: alpha-tocopheryl acetate Table 2. P-values of FAP in trout fillets as affected by supplementing trout with FO and α-TA (p-value=0.05) American Heart Association indicated that omega-3 fatty acids (ω-3 FA) in fish or fish products reduce the risk of cardiovascular disease. Institute of Medicine and the Food and Nutrition Board suggested intake levels for n-3 polyunsaturated fatty acids (PUFA) at 1.6 g for men and 1.1 g for woman. Flaxseed oil contains the highest concentration of α-linolenic acid (ALA) compared to other lipid sources used in fish feeds. An ω-3-enhanced rainbow trout (Oncorhynchus mykiss) was raised successfully on our research farm. However, it is known that lipid oxidation is one the major problems in fish products. Moreover, polyunsaturated fatty acids are more easily oxidized than saturated fatty acids. Fat-soluble antioxidants, such as vitamin E, play an important role in preventing the oxidation of polyunsaturated fatty acids. Alpha-tocopheryl acetate (α-TA), a vitamin E derivative, is usually used as an antioxidant to reduce lipid oxidation in food. The α-TA is the most effective lipid-soluble antioxidant. Animal and human studies suggest that the amount of vitamin E required to prevent lipid peroxidation inside the body increases with the amount of polyunsaturated fat consumed. Our hypothesis is that supplementing fish diet containing high concentration of FO withα-TA will reduce lipid oxidation of ω-3-enhanced rainbow trout fillets during storage at 2C. • FO: flaxseed oil; α-TA:alpha-tocopheryl acetate. • Experimental design: 2x2 factorial arrangement of treatment in a randomized complete block design. • Test parameters: moisture, alpha-tocopherol & total fat content, fatty acid profile, and lipid oxidation (TBARS). • The highest (P<0.05) fat content in fillets was observed in basal diet group, followed by basal diet + 15% FO + 1500ppm α-TA, basal diet + 15% FO, and basal diet + 1500ppm α-TA groups for storage of 12 days. • Regardless of supplementing basal diets with α-TA and packaging method, FO reduced (P<0.05) α-tocopherol contents but increased (P>0.05) TBARS in fillets. That might be due to lipid oxidative retardation by consuming α-TA. • Regardless of supplementing basal diets with FO and packaging method, α-TA increased (P<0.05) α-tocopherol contents in fillets. FO: flaxseed oil; α-TA: alpha-tocopheryl acetate ALA: alpha-linolenic acid; EPA: Eicosapentaenoic acid; DHA: Docosahexaenoic acid FO: 0% & 15%; α-TA: 0 & 1500ppm Fig 1: Fat (%) of trout fillets as affected by supplementing trout FO and α-TA (20C for 12d-storage) Table 3. FAP in trout fillets as affected by supplementing trout with FO and α-TA Our objectives were to evaluate the effects of FO and α-TA supplementations on lipid oxidation, FAP, and alpha-tocopherol content of trout fillets during storage at 2 0C. • Regardless of supplementing basal diets with FO or α-TA, vacuum packaged fillets showed higher (P<0.05) α-tocopherol content than aerobic packaged ones. A vacuum package hinders oxygen contact with fillets. Therefore, α-TA may be required at lower concentration to retard lipid oxidation. • There are interactions (P<0.05) between FO and α-TA on FAP. Regardless of packaging method, when supplementing basal diet with 15% FO + 1500ppm α-TA, the lowest (P<0.05) proportion of saturated FA and DHA, as well as the highest (P>0.05) proportions of unsaturated FA, total ω-3 FA, α-linolenic acid, and EPA in the fillet’s lipid were obtained. • The results demonstrated that the vacuum packaging reduced lipid oxidation. To maintain ω-3 FA during storage in trout fillets obtained from FO supplemented trout, the feed should be supplemented with α-TA.