Oxidative stability of seed oils extracted with supercritical carbon dioxide 1

Abstract

Abstract Dry‐milled corn germ, soybean and cottonseed flakes were extracted (at 70‐90 C and 12,000 psi) with supercritical carbon dioxide (SC‐CO 2 ) to yield crude oils. Oxidative stability of the crude oils was determined and compared to similar products obtained by conventional expeller and/or prepress solvent extraction. Under Schall oven storage conditions (60 C), SC‐CO 2 ‐extracted oils undergo rapid deterioration and fail to show the normal induction period observed with conventional expeller and solvent‐extracted crude oils. The levels of tocopherols found in SC‐CO 2 ‐extracted oils are comparable to those obtained by expeller or solvent extraction, while phospholipids present in significant amounts in conventional crude oils are essentially absent from SC‐CO 2 ‐processed crudes. The addition of phosphatides to SC‐CO 2 ‐extracted crude oils improves oxidative stability, which suggests that both tocopherols and phospholipids are required to stabilize crude oils against autoxidation. Heating of SC‐CO 2 ‐extracted crude oils to deodorization temperatures improves oxidative stability. The destruction of fat hydroperoxides under these conditions probably accounts for improved oxidative stability. A combination of heat and the addition of citric acid and phenolic antioxidants resulted in further improvement of oxidative stability.