Deacidification of high-acid rice bran oil by the tandem continuous-flow enzymatic reactors

Rice bran oil (RBO) contains a variety of nutrients, but the high acid values largely hinder its processing into edible oil. Thus, the tandem continuous-flow reactors are proposed and developed for the enzymatic deacidification of RBO and simultaneous production of functional oils. The results indicate that the Candida antarctica lipase B (CALB) immobilized on the hydrophobic ordered mesoporous silicon (OMS-C-18) increased 6.6 times of the catalytic activity and improved at least 20 C-o of temperature tolerance compared to the commercial Novozym 435. The tandem continuous-flow enzymatic reactors removed 91.4% of free fatty acid and increased 9 and 12 times of phytosterol ester and diacylglycerol in RBO, respectively. Moreover, the retention rate of gamma-oryzanol was at least 40% higher than that obtained by traditional alkali refining. This study provides an effective and sustainable method to continuously convert the low-value RBO into value-added products, which brings huge potential to cleaner industrial production.

Automated summary

Tandem continuous-flow reactors were developed for enzymatic deacidification of rice bran oil (RBO) and simultaneous production of functional oils. The immobilized Candida antarctica lipase B (CALB) on hydrophobic ordered mesoporous silicon (OMS-C-18) showed significantly increased catalytic activity and temperature tolerance compared to Novozym 435. The tandem continuous-flow enzymatic reactors effectively removed free fatty acid and increased the content of phytosterol ester and diacylglycerol in RBO, while retaining a higher percentage of gamma-oryzanol compared to traditional alkali refining.