Effects of Oil Extraction Methods on Physical and Chemical Properties of Red Salmon Oils (Oncorhynchus nerka)

Abstract

AbstractThe following four methods were used to extract salmon 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; and RS4 involved ground red salmon heads, enzymatic hydrolysis, enzyme inactivation by heat and centrifugation. The four extracted oil samples were evaluated for chemical, thermal, and rheological physical properties. The RS4 process recovered significantly higher amounts of crude oil from red salmon heads than the other three extraction methods, while containing a higher % of free fatty acids and higher peroxide values than RS1, RS2, and RS3 oils. Oleic acid, eicosenoic acid, EPA, and DHA were the predominant fatty acids accounting for about 60% of all unsaturated fatty acids. The RS1, RS2, RS3, and RS4 extractions contained 9.3, 9.05, 9.35, and 9.45% of EPA and 8.8, 8.55, 9.0, and 9.1% of DHA in the oil, respectively. Weight losses of the oils increased with increasing temperatures between 200 and 500 °C. The % weight losses at 500 °C were 94.50, 94.58, 94.94, and 95.47% for RS2, RS1, RS3, and RS4, respectively. The apparent viscosities of all the oil samples decreased with the increases in the temperature. The RS1 extract was more viscous (P < 0.05) than those of RS2, RS3, and RS4 between 0 and 25 °C.