ARS | Publication request: The Effect of Starch Type and Oil Content on Oxidation of Starch-Soybean Oil Composites

Submitted to: Annual Meeting of the Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: June 25, 2006
Publication Date: June 25, 2006
Citation: Winkler, J.K., Singh, M. 2006. The effect of starch type and oil content on oxidation of starch-soybean oil composites [abstract]. Annual Meeting of the Institute of Food Technologists. Paper No. 34-03.

Technical Abstract: Starch-oil composites (SOCs) are stable suspensions of microscopic (1-10 um) oil droplets in a starch dispersion or gel. These dispersions can be dried and reconstituted into an aqueous system without the need for emulsifiers, yet will maintain their physical stability and properties. SOCs have been used as fat replacers and stabilizers in beef patties, dairy products, and baked goods, and they have potential use for delivery of lipid soluble flavors, antioxidants, or nutraceuticals into aqueous food systems. However, the oil in SOCs is susceptible to oxidation. The objective of this study was to obtain a better understanding of how starch type, as well as the ratio of oil:starch, affects the oxidation rates in dried SOCs. Oxidative stability of SOCs made with either waxy or regular food-grade corn starch, and 10, 20, 30, or 40% oil (weight/weight of starch) was investigated. Peroxide values (PV’s) and hexanal were analyzed in composites stored at 60 deg C for eight days. Initial PV’s as well as oxidation rates were much higher in oil extracted from composites compared to the oil before being incorporated into the SOCs, indicating that the jet-cooking process promoted oxidation. Starch type did not affect oxidation rates during storage. The rate of oxidation in food-grade SOCs was not affected by the oil percentage, however, those SOCs made with 10% oil had significantly higher initial PV’s compared to SOCs with higher oil content. Waxy SOCs made with 10% oil also had significantly higher initial PV’s, but the rate of oxidation was actually lower than SOCs made with 30% oil. This research indicates that the jet-cooking process promotes oxidation of SOCs, which could reduce their overall shelf-life. Steps should be taken in the jet-cooking, drum-drying process, including using higher oil:starch ratios, to improve the oxidative stability of SOCs.