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Blending palm oil with flaxseed oil or menhaden fish oil to produce enriched omega-3 oils for deep-fat-frying

University of British Columbia

Two of the major dietary food sources of omega-3 fatty acids are flaxseed oil and fish oil; the former being a rich source of PUFA (e.g. α-linolenic acid (α-LA)), while the latter is a source of HUFA (e.g. eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)). In this study, palm oil, a commonly used vegetable oil that is widely available in Asian and African countries, was blended with flaxseed (omega 3-PUFA) and fish oil (menhaden oil) (omega-3 HUFA); respectively, to obtain blended oils that both contained a 1: 4 ratio of omega-3 :omega 6 fatty acids. Rosemary extract (0.02% w/w) was added to the oil blends to stabilize the oil during use for deep-fat frying. Eight hours of heating at 180 °C was used to determine the stability of omega-3 fatty acids and uptake from the omega-3 enriched palm oil into fried potatoes. Lipid oxidation and thermal degradation of the palm oil blends, along with retention of α-LA , EPA, and DHA were measure of oil blends stability. Linoleic acid content in flax-palm oil blend did not change during frying when in the presence of different antioxidant treatments. The α-LA content of heated flax-palm oil blend was significantly reduced (P<0.05) after 8 hours of frying. Meanwhile, linoleic acid and EPA content in the fish-palm oil blend revealed significant (P<0.05) decreases in concentration after 8 hours of frying regardless of the presence of antioxidant. The DHA concentration was significantly lower when present in the absence of antioxidant (P<0.05). Totox significantly increased (P<0.05) in the blended oils after 8 hours of frying; albeit the extent of oxidation and thermal degradation was reduced when rosemary extract was added. A significant uptake of omega-3 fatty acids in both the omega-3 PUFA (e.g. α-LA) and HUFA (e.g. EPA and DHA), respectively, occurred in potatoes fried in the respective blended oils. Although omega-3 fatty acid uptake was prevalent in potatoes fried in both blended oils, the effect of heating reduced the optimal 1:4 ratio of omega-3 :omega-6 to a 1:6-l :7 ratio. This loss in omega-3, relative to omega- 6, was attributed to thermal oxidation; a reaction not totally preventable by adding antioxidants to the frying oils. These functional omega-3 enhanced oils when used to process potatoes gave forth products that represented 1/10th suggested intake for EPA+DHA and l/50th the daily requirement for α-LA .

Text

2011-03-12

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http://hdl.handle.net/2429/32399

Food Science

University of British Columbia

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