Oxidation of fish oil oleogels formed by natural waxes in comparison with bulk oil

Authors: Hwang, Hong-Sik; FHANER, MATTHEW - UNIVERSITY OF MICHIGAN; Moser, Jill; Liu, Sean

Submitted to: European Journal of Lipid Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2018
Publication Date: 3/30/2018
Citation: Hwang, H.-S., Fhaner, M., Winkler-Moser, J.K., Liu, S.X. 2018. Oxidation of fish oil oleogels formed by natural waxes in comparison with bulk oil. European Journal of Lipid Science and Technology. doi: 10.1002/ejlt.201700378.
DOI: https://doi.org/10.1002/ejlt.201700378

Interpretive Summary: The consumption of omega-3 oil supplements and foods fortified with omega-3 oils has dramatically increased due to their beneficial health effects such as reducing the incidence of heart attacks, reducing inflammation and the brain development in fetuses. One serious drawback of omega-3 oils is that these oils oxidize much faster than other oils. The oxidation of omega-3 oils negatively impact on flavor and odor of the product and, more seriously, on human health. Therefore, protecting omega-3 oils including fish oil from oxidation during manufacturing, storage, and transportation is very important. In this study, we evaluated the oleogel technology as a new method to prevent oxidation of fish oil. An oleogel is a gel made of oil. When oil was converted to oleogel using natural waxes, the oxidation of fish oil was effectively reduced. Four different natural waxes were compared for the effectiveness at two different temperatures 35 °C and 50 °C. A new method, the color penetration measurement method, was developed as a faster and more convenient method to predict the oxidation rate of oleogel. Cooling the oleogel at a faster rate could significantly reduce the oxidation rate of the oleogel. The most effective wax amount was determined since it was found that a larger amount of wax did not necessarily give a better effect. It was concluded that the oleogel technology could be a good method to protect omega-3 oils from oxidation. It should be noted that waxes used in this study are all natural, inexpensive, and potentially beneficial for health.

Technical Abstract: The aim of this study was to evaluate the oleogel (or organogel) technology as a new method to prevent oxidation of fish oil by immobilizing oil and to provide useful information on oxidation of oleogels for their application in actual food products. Four different natural waxes, rice bran wax, sunflower wax, candelilla wax, and beeswax were used to prepare fish oil oleogels. Peroxide value, conjugated diene value, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) were measured after storing oleogels at 35 °C and 50 °C, respectively. All 3% wax-fish oil oleogels showed slower oxidation than the bulk fish oil at 35 °C. Beeswax was not as effective as other waxes during storage at 50 °C due to its lower melting point. The color penetration measurement method was developed as a convenient method to predict the oxidation rate of oleogel. Cooling oleogel at a faster rate could significantly reduce the oxidation rate of the oleogel. A larger amount of wax is not recommended to increase the protective effect, which can give a negative effect due to the prooxidant activity of wax. The oleogel technology may be applied to reduce oxidation of products containing omega-3 oil such as foods and nutritional supplements.