Submitted to: Annual Meeting of the Institute of Food Technologists
Publication Type: Abstract only
Publication Acceptance Date: 3/15/2008
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: In Alaska, discarded salmon heads represent a food-grade source of valuable long-chain n-3 polyunsaturated fatty acids (PUFAs). However, these highly unsaturated marine oils are susceptible to oxidation. This research explored smoke-processing as a technology to reduce oxidation of salmon oil during storage. Pink salmon (Oncorhynchus gorbuscha) heads from Kodiak Alaska were smoked (1 to 5 hrs; 55°C to 95°C) and analyzed for composition (lipid, protein, moisture, and ash). Oils were extracted and lipid oxidation was assessed (using TBARS, Free Fatty Acids, and Peroxide Value). Fatty acid analysis for n-3 PUFA content and antioxidant activity were also measured. Shelf life stabilities of extracted oils and oils stored within the smoked salmon heads before extraction were evaluated at 4°C and 35°C for 8 days. Fewer products of oxidation were found in oils extracted from hot-smoked salmon heads (95°C, 5 hrs), than in oils from raw salmon or traditional extraction (95°C, 50 min). As smoking times and temperatures increased, levels of oxidative products decreased in the oils. After seven days of storage, oils from smoked salmon heads displayed consistently lower oxidative values than raw oils. Additionally, oils protected within salmon heads during smoking (70°C, 4 hrs) retained n-3 PUFA quantities equal to frozen controls. The smoking process also extended the shelf life of salmon heads. More acidic products accumulated in 5-hr smoked fish heads than during shorter smoking intervals. After oil extraction, the remaining smoked material decreased to pH 4.8 within 7 days, with no offensive “fishy” odor detectable during storage. Preservation of salmon heads through high-temperature smoking exposes tissues to phenolic derivatives, thereby reducing oxidation of valuable PUFA-rich oils. Extending the storage time of salmon oils will benefit Alaska's fish processing industry by facilitating long-distance transport before spoilage occurs.