The nonpolar fraction of the deteriorated oil and fats is made up of all unaltered triacylglicerols. Total polar compounds are considered to be nonvolatile compounds that have a higher polarity than triacylglycerols as a result of thermal, hydrolytic and oxidative alteration. Consequently, the higher the amount of polar compounds on oil, the worse its quality is (Gharachorloo et al. 2010).
According to Lumley (1988), the initial contents of total polar compounds in oil should range between 0.4 and 6.4%. The results of initial samples of soybean oil are within the limits set for refined oils