Modification of marine oils and their biological significance

Wang, Jiankang (2012) Modification of marine oils and their biological significance. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Marine oils, such as seal blubber and menhaden oils offer a wide range of health benefits and play a critical role in many functions in the human body. Their effects in alleviating cancer cardiovascular disease, psychiatric disorders, Parkinson's disease and inflammatory ailments have been well demonstrated in a large body of literature. However, these oils are highly vulnerable to oxidation due to their high content of polyunsaturated fatty acids (PUFA). There are a number of means to modify these marine omega-3 oils in order to change their chemical and physical properties including randomization, blending and acidolysis. In this study, the effect of randomization using both chemical and enzymatic catalysts, as well as blending with antioxidant rich-wheat germ oil on the oxidative stability of seal blubber and menhaden oils was investigated. Meanwhile, lipase-catalysed acidolysis of p-coumaric acid with triolein, seal blubber and menhaden oils was carried out in this work, followed by examination of the antioxidant activities of the synthesized phenolic lipids in in vitro assays, food and biological systems. The results indicated that both chemical and enzymatic randomization lead to the redistribution of fatty acids among the stereoisomeric sn-1 ,3 and sn-2 positions of the glycerol moiety of triaclyglycerols of seal blubber and menhaden oils. The changes in oxidative stability were due to the loss of tocopherol and positional redistribution of fatty acids, especially the unsaturated fatty acids. Blending with wheat germ oil modified fatty acid composition and increased the tocopherol content of seal blubber and menhaden oils, hence improving the oxidative stability of blended seal blubber and menhaden oils, mainly due to the increased content of tocopherols, especially gamma- and deltatocopheols as the total content of unsaturated fatty acids before and after blending was similar. Therefore, wheat germ oil served as a good stabilizer for marine oils tested. Phenolic lipids derived from triolein, seal blubber oil and menhaden oil showed good antioxidant potential in systems tested. The prepared phenolic lipids exhibited high scavenging capacity towards 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and peroxyl radicals, and displayed reducing power, strong inhibitory effect in bleaching ~-carotene, human low-density lipoprotein (LDL) cholesterol oxidation as well as radical-induced DNA cleavage, which suggests that phenolic lipids derived from seal blubber and menhaden oils may be used as potential stable marine oils for health promotion and disease risk reduction.

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