ALASKA FISH PROCESSING BYPRODUCTS
Title: Effects of oil extraction methods on physical and chemical properties of red salmon oils (Oncorhynchus nerka)
Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 4, 2011
Publication Date: October 20, 2011
Citation: Yin, H., Wan, Y., Huang, J., Sathivel, S., Bechtel, P.J. 2011. Effects of oil extraction methods on physical and chemical properties of red salmon oils (Oncorhynchus nerka). Journal of the American Oil Chemists' Society. 88(10):1641-1648. DOI 10.1007/s11746-011-1824-x..
Interpretive Summary: Producing and purifying oil from red salmon heads for the growing fish oil market can benefit the salmon industry. Extracting oil from red salmon heads can add value to red salmon byproducts, which are often under utilized. The objective of the study was to compare different extraction methods on the chemical, nutritional, thermal, and rheological properties of red salmon oil extracted from red salmon heads. This study demonstrated the effect of the extraction methods on chemical, thermal, and rheological properties of red salmon oil. The data will be useful for designing the purification process of the fish oils. Salmon oil which was produced by an enzymatic extraction process recovered more oil but had higher % free fatty acid and peroxide values than other extraction methods. All oil samples had similar fatty acid profiles and similar levels of the long chain omega-3 fatty acids EPA and DHA. The oil samples contained different amount of minerals and the apparent viscosity of the oils decreased with increased temperature. Information on chemical, thermal and rheological properties from this study can be used for the design of a purification processes to produce red salmon oil as food and feed ingredients.
Four different red salmon oil extraction processes were used to extract oil from red salmon heads: RS1 involved a mixture of ground red salmon heads and water, no heat treatment, and centrifugation; RS2 involved ground red salmon heads (no water added), heat treatment, and centrifugation; RS3 involved a mixture of ground red salmon heads and water, heat treatment, and centrifugation; RS4 involved ground red salmon heads, enzymatic hydrolysis, and centrifugation. The four oil samples were evaluated for chemical and physical properties. The RS4 process recovered significantly higher amounts of crude oil from red salmon heads than the other three extraction methods, while contained higher % free fatty acid and peroxide values than RS1, RS2, and RS3 oils. Oleic acid, eicosenoic acid, EPA, and DHA were the predominant fatty acid methyl esters accounting for about 60% of all unsaturated fatty acids. The four treatments had EPA values as a % of oil ranging from 8.09, to 8.37 % and DHA values ranging from 7.97 to 8.43 %. Weight loss of oils increased with increasing temperatures between 200 and 500C. The weight loss at 500C was 94.50, 94.58, 94.94, and 95.47% for RS2, RS1, RS3, and RS4, respectively. The apparent viscosity of all the oil samples decreased with the increase of the temperature. The RS1 was more viscous (P<0.05) than RS2, RS3, and RS4 between 0 to 25C.