Enzymatic esterification of rice bran oil and phytosterol in supercritical CO 2

Abstract

In this paper, the esterification of phytosterol and free fatty acids (FFA) in rice bran oil (RBO) was studied using Novozym 435 in supercritical CO₂. It was found that with the increase in CO₂ filling pressure, the esterification reaction rate also increased. When the pressure exceeded the critical point, CO₂ fluid had a great effect on phytosterol conversion. Therefore, enzymatic esterification deacidification was studied when the CO₂ filling pressure was 8.0 MPa, the results showed that when the lipase dosage was 3.0%, the phytosterol concentration was 18.0%, the molecular sieve addition was 10.0%, and the esterification temperature was 78°C, after 41 hr the FFA content of RBO decreased to 1.1%, the phytosterol conversion rate reached 93.2%, and the vitamin E (VE) retention in the product was 80.0%. Therefore, the esterification by Novozymes 435 in supercritical CO₂ could have several applications in fats and oils industry. PRACTICAL APPLICATIONS: Much research has been done on the interesterification of vegetable oil in order to produce edible fats and oils. The current study provides a reliable and simple method for the esterification of phytosterol and free fatty acids (FFA) in rice bran oil (RBO). The optimal operating conditions lead to high quality oil. The FFA content of RBO decreased to 1.1%, the phytosterol conversion rate reached 93.2%, and the VE content in the product was 80.0%. The esterification by Novozymes 435 in supercritical CO₂ could be applied in fats and oils industry.