Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 27, 2006
Publication Date: N/A
By-products from Alaska’s fishing industry represent an underutilized resource often subject to disposal costs rather than economic benefits. In some locations these high-protein discards are preserved as fishmeal, however during this processing, valuable compounds may be lost or diminished. Currently, the demand for salmon oil is increasing, as n-3 long-chain polyunsaturated fatty acids (PUFA) gain recognition for their health benefits. Oil extraction prior to fishmeal processing is not always possible. Other techniques exist for preserving salmon, but have not been evaluated for their effectiveness in retaining the value of salmon oil in by-products. The objective of this research was to explore alternative processing methods that might prove useful for retaining the maximum quality of high-value n-3 PUFAs in salmon by-products.
In this study, five different processing methods were used to preserve Coho salmon (Oncorhynchus kisutch), before evaluating the fatty acid profiles. Samples were smoked (27 °C, 3h), pressure-cooked (70 kPa, 2 h), frozen (-20 °C), salted (23 °C), or pickled (salted for 4 days, then stored in vinegar). All samples were stored for 90-days before analysis. Salmon heads were also included because of their high oil content. Heads were frozen for 90-days, then cooked in water (100 °C, 0.5 h) before testing. All lipid extractions were performed using an isopropanol/hexane solvent. Fatty Acid Methyl Esters were prepared and then analyzed using Gas Chromatography with Flame Ionization Detection.
Total fatty acids (per 100 g of tissue) for smoked samples and pressure-cooked fillets were similar to their untreated controls (stored at -80 °C). However, salting, freezing, or pickling the fillets decreased the fatty acid content by approximately half. The highest n-3 PUFA values occurred with smoked and pressure-cooked salmon, which retained 94% of their original n-3 PUFAs as compared to the control fillet. Freezing, salting, and pickling were less effective at preserving n-3 PUFAs, retaining only 58%, 54%, and 43% (respectively) of their original quantities. Salmon heads were found to contain over 300% more total fatty acids than the fillets, losing only 15% when heat-processed. The heads also retained over 90% of their n-3 PUFA after cooking. The results of this study may provide direction for handling and storage of underutilized fish by-products in order to retain the maximum levels of high-value n-3 long-chain polyunsaturated fatty acids.