Marine oils : stabilization, structural characterization and omega-3 fatty acid concentration

• Main Author: Wanasundara, Udaya Nayanakantha
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 1996
• Subjects: Newfoundland
• Online Access: https://research.library.mun.ca/1258/; https://research.library.mun.ca/1258/1/Wanasundara_UdayaNayanakantha.pdf; https://research.library.mun.ca/1258/3/Wanasundara_UdayaNayanakantha.pdf

Marine oils are obtained from the flesh of fatty fish, liver of lean fish and blubber of marine mammals. Seal blubber, a major product from the seal fishery, is abundantly available in Newfoundland and Labrador, but its characteristics have not been adequately defined. In this work, seal blubber oil (SBO) and cod liver oil (CLO) were extracted and refined under laboratory conditions. During each step of refining, oils were assessed for their oxidative stability by accelerated oxidation under Schaal oven conditions at 65°C over a 6 days period. Progression of oxidation was monitored by employing peroxide value (PV) determinations and 2-thiobarbituric acid reactive substances (TBARS) tests. Oxidative stability of processed oils after alkali-refining, degumming and deodorization steps was lower than that of crude oils, which is due in part to the removal of natural antioxidative compounds during refining. Oxidative stability of refined-bleached and deodorized (RBD) SBO and CLO was compared with that of commercially available menhaden oil (MHO); SBO exhibited a higher oxidative stability than CLO or MHO, perhaps due to its low content of polyunsaturated fatty acids (PUFA). -- Different procedures were examined for improving the oxidative stability of SBO and/or MHO. Particularly emphasis was placed on the use of natural antioxidants. Dechlorophyllized green tea extracts (DGTE, 100 to 1000 ppm), individual tea catechins [(-)epicatechin (EC), (-) epigallocatechin (EGC), (-)epigallocatechin gallate (EGCG), (-)epicatechin gallate (ECG)] and commercially-available flavonoids (apigenin, kaempferol, morin, myricetin, naringin, naringenin, quercetin, rutin and taxifolin) at 200 ppm levels were added to both test oils. Oxidative stability of treated oils was determined and compared to those treated with conventional antioxidants such as α-tocopherol at 500 ppm and BHA, BHT and TBHQ at 200 ppm levels. Progression of oxidation was monitored by employing weight gain, PV and TBARS tests. DGTE at 500 and 1000 ppm and individual ...