Effects of Processing on the Oxidative Stability of Docosahexaenoic Acid Oil
Keywords:DHA processing lipid oxidation
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Series/Report no.:2011 Edward F. Hayes Graduate Research Forum. 25th
Docosahexaenoic acid (DHA) is an omega-3 fatty acid which is essential for normal brain and retinal development. A deficiency in fetal cerebral DHA content has been associated with preterm delivery, which may lead to higher risks for autism, ADHD, and schizophrenia. Western diets are deficient in DHA intake, making the development of DHA-enriched products a growing facet of the food industry. The poor oxidative stability of DHA has made the development of such products challenging, as the oxidation is rapid and produces off-odors and flavors, making the product unacceptable to consumers. Effects of refining, bleaching, winterizing, and deodorizing on the oxidative stability of DHA (22:6 Ω-3) oil were studied by a combination of headspace oxygen depletion (HOD) by gas chromatography and total volatile compound formation by SPME-GC. Results for both showed that refined oil was significantly (p < 0.05) less stable than bleached, winterized, and deodorized oils. The oxygen content in the refined, bleached, winterized, and deodorized DHA oil samples decreased from 20.9% on Day 0 to 6.7%, 8.3%, 7.8% and 7.8%, respectively on Day 5. The bleached, winterized, and deodorized oils were determined not to be statistically different from each other (p > 0.05), however the refined oil showed significantly more HOD (p <0.05), corresponding to a lower oxidative stability. Refined, Bleached, winterized, and deodorized oils showed average volatile compound formations over 5 days of storage of approximately 4,041,000 electronic counts (ec), 482,100 ec, 437,200 ec, and 405,800 ec, respectively. The refined samples again showed significantly (p < 0.05) higher volatile compound formation, corresponding to a lower oxidative stability. The bleached, winterized, and deodorized samples were not significantly different from each other (p > 0.05). Bleaching proved to be the crucial processing step in increasing the oxidative stability of DHA oil. Optimizing the bleaching process may be an important first step in increasing the oxidative stability of DHA oil.
Food, Agricultural, and Environmental Sciences (FAES): 3rd Place (The Ohio State University Edward F. Hayes Graduate Research Forum)
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