Location: Functional Foods ResearchTitle: New antioxidants and antioxidant systems for improvement of the stability of vegetable oils and fish oils Author
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/7/2016
Publication Date: 11/10/2016
Citation: Winkler-Moser, J.K., Hwang, H.-S., Liu, S.X. 2016. New antioxidants and antioxidant systems for improvement of the stability of vegetable oils and fish oils [abstract]. UJNR Food and Agriculture Panel.
Technical Abstract: Most vegetable oils and fish oils contain polyunsaturated fatty acids ranging from 18 carbons with two to three double bonds, to 22 or 24 carbons, and up to six double bonds. Nutritional research over the years has indicated that individual fatty acids from the diet play a complex role in nutrition and disease. Replacing saturated fats and industrially produced trans fats with polyunsaturated fats has been shown to reduce plasma total cholesterol, LDL cholesterol, blood triglycerides, and to lower the risk of heart disease, which is the leading cause of death in the U.S. and in many other countries. Therefore, expert panels, such as the U.S. Department of Agriculture and U.S. Department of Health and Human Services Joint Dietary Guidelines Committee, the American Dietetic Association, and the American Heart Association recommend that solid fats containing saturated and trans fats be replaced as much as possible with oils containing monounsaturated and polyunsaturated fatty acids. Unfortunately, polyunsaturated fatty acids are highly susceptible to lipid oxidation, a free radical catalyzed chain reaction (autooxidation), which, depending on the conditions, produces oxidized fatty acids, polymerized triacylglycerols, short-chain volatile compounds, reactive oxygen species, and reactive aldehydes such as acrolein and 4-hydroxynonenal. Lipid oxidation is a major cause of reduced shelf-life and food waste, because even in the early stages of the oxidation process, there are off-flavors and odors that can be detected by consumers. Autooxidation rates increase with an increasing number of double bonds, but rates of lipid oxidation in food processing and storage environments are also affected by many other factors such as temperature, oxygen availability, light intensity, and the presence of antioxidants. Antioxidants can, by various mechanisms, prevent or slow the rate of autooxidation. But consumers are wary of the synthetic antioxidants that are used by the food industry, such as butylated hydroxylanisole (BHA), butyl hydroxyltoluene (BHT), and tert-butylhydroquinone (TBHQ). Therefore, a major aim of our research group has been on the development of new antioxidants or antioxidant systems based on natural extracts or naturally produced compounds. Phytosteryl ferulates are composed of a phytosterol esterified to ferulic acid, a phenolic antioxidant. These compounds are found in grains such as wheat, rye, rice, and corn. A number of studies have shown that these compounds have antioxidant activity in oils and emulsions. Phytosteryl ferulates are good candidates as frying oil antioxidants, first, because esterification of ferulic acid to a phytosterol increases its molecular weight, which would prevent volatilization, and second, because it enhances its solubility in oil. In addition, phytosteryl ferulates are expected to have strong stability because studies in our group indicated that phytosterols had good stability to frying. Therefore, the objectives of the studies presented here were, first, to evaluate the antioxidant activity of purified corn and rice phytosteryl ferulates, as well as corn fiber extracts that contain phytosteryl ferulates, in soybean oil used for frying. The second objective was to evaluate the impact of the structure of the phytosterol head group on their antioxidant activity. Soybean oil was kindly provided by ADM. Corn phytosteryl ferulates were extracted and purified using preparative HPLC from corn distillers grain oil and corn fiber oil. Rice phytosteryl ferulates (oryzanol) were obtained commercially. Pure phytosteryl ferulates were synthesized as described by Winkler-Moser et al. Miniature frying studies and heating studies and and oil analyses were conducted as described by Winkler-Moser et al. Corn fiber extracts were obtained by Soxhlet extraction with hexanes. Hexane was removed by rotary evaporation,