Unsaponifiable Matter and Oxidative Stability of Commercially Produced Indian Rice Bran Oils

Chemically and physically refined rice bran oils (RBO) were investigated for their content and composition of unsaponifiable matter and oxidative stability. The chemically and physically refined rice bran oils contained 2.6 and 4.5% unsaponifiable matter, respectively. The content and composition of unsaponifiable matter for chemically and physically refined RBO were phytosterols, 0.96%and 1.40%; 4‐methyl sterols, 0.51%and 1.12%; triterpene alcohols, 0.52% and 0.86%; and nonpolar components, 0.61% and 1.13%, respectively. The corresponding oxidative stability for the two oils were 2.80 h and 4.37 h, respectively. The content of unsaponifiable matter was influenced by residual amounts of wax and oryzanol in the refined oil as shown by the model experiments. Thus physical refining of rice bran oil requires a thorough dewaxing step to obtain a refined oil without haziness and with a lower amount of unsaponifiable matter.