Oxidative stability of soybean oil at different stages of refining

Oxidative stabilities of soybean oil samples at 7 different stages of commercial refinement were measured by weight increases. Also, a method was developed for isolating essentially pure soybean triglyceride, and its oxidative stability was measured. Crude oil was most stable and the highly purified soybean triglyceride was least stable, with other samples being intermediate in stability. Adding phospholipids and tocopherols to the highly purified soybean triglyceride gave its oxidative stability, and in combination they were synergistic in delaying oxidation. The weight increase method demonstrated that surface exposure is an important variable in rates of autoxidation.