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Electrochemical hydrogenation under a mixed gas environment of CO2 and H2 was studied. It was found that in supercritical CO2 (SC‐CO2), the mole fraction of H2 in both the CO2 and electrolytes increased as H2 pressure increased. CO2 was dissolved in the electrolyte to form unstable carbonic acid, which was easily decomposed into HCO3- and H+. Meanwhile, H2 was electrolyzed to form H+ at the anode, so that the conductivity increased, the hydrogen consumption of the reaction increased, and then tended to be stable at a total pressure of 9.0 MPa. Herein, the electrochemical hydrogenation of soybean oil was accomplished at a current of 120 mA, a temperature of 50°C, and an agitation speed of 300 rpm. The iodine value (IV) of the hydrogenated soybean oil was 90.6 g I2/100 g oil at 7 hr and the trans fatty acid (TFA) content in the oil was 3.32%. Practical applications In the present study, H2 was added to the electrochemical hydrogenation reactor and soybean oil was electrochemically hydrogenated by filling H2 in supercritical CO2. By filling H2, the TFAs of the hydrogenated soybean oil were reduced, and the TFA content was only 3.32%. The reaction rate of the hydrogenation was faster and the hydrogenation time decreased by 5 hr compared with the hydrogenation of soybean oil at a normal pressure. Moreover, the electrochemical hydrogenation reactor used a moderate pressure and a large reaction volume, which is beneficial to industrialization. The electrochemical hydrogenation by filling H2 in SC‐CO2 decreased the hydrogenation time and reduced the industrial production costs. This method can be further applied for industrial purposes.

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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.