Characteristics, immobilization of linoleic acid isomerase from Bifidobacterium breve and its application in rice bran oil

The purpose of this paper is to reduce the acid value of rice bran crude oil and make a new rice bran oil (RBO) with conjugated linoleic acid (CLA). Linoleic acid isomerase from Bifidobacterium breve was immobilized on a magnetic nanoflower carrier of Fe₃O₄-SiO₂-NFs. Molecular docking simulations were performed to investigate the interaction and binding mode conformation between isomerase and linoleic acid (LA) molecules by using computer software. This isomerase was used in isomerization reaction of high acid value RBO. Under the optimal enzymatic isomerization conditions, the conversion rate of LA was 62.13 %. The content of c9-CLA and t11-CLA in the product of enzymatic isomerization reaction was 23.50 ± 0.25 %. After six repeated uses, the relative activity of the immobilized enzyme remained above 70 %. Esterification reaction was performed from monoacylglycerol and RBO with CLA under the catalysis of magnetic immobilized lipase. The CLA glyceride content was 14.09 ± 0.53 % in new RBO product. The acid value of RBO decreased to 0.31 ± 0.15 mgKOH/g, and the peroxide value was 1.03 ± 0.14 mmol/kg. It may provide a sustainable pathway for RBO refining that combines deacidification with CLA-functionalization.