Pre-treatment of ferulic acid esterases immobilized on MNPs to enhance the extraction of ferulic acid from defatted rice bran in presence of ultrasound

•Combined effect of ultrasound and enzyme, enhanced the FA yield with minimum time.•Enzyme was used in pre-treatment method, to avoid its denaturation in contact with ethanol.•Use of ferulic acid esterase immobilized magnetic nanoparticles allows the reusability of enzyme.•Obtained FA acid showed good radical scavenging activity and total phenolic content.

Ferulic acid (FA) extraction is a tough task due to its linkage with the hemicellulose, which is difficult to break. An ultrasound assisted enzymatic pre-treatment method was established to improve the yield of FA. Defatted rice bran (DFRB) was pre-treated using ferulic acid esterase (FAE) immobilized on magnetic Nanoparticles (MNPs) in presence of ultrasound. One factor at a time method for pretreatment was used to achieve maximum FA yield. Further the central composite design (CCD) was determined and under predicted optimum condition maximum yield was achieved up to 3.69 mg/g of DFRB. Optimum parameters were DFRB to solvent ratio 1:32 (w/v), temperature 42.2 °C, enzyme loading 2.82% and sonication power 84.85 W. The FA yield by conventional enzymatic method was 3.14 mg/g after 4 h whereas the yield was enhanced to 3.69 mg/g with pre-treatment time reduced to 1 h by ultrasound assisted enzymatic treatment. Total phenolic content was 3.86 mg GAE/g and DPPH scavenging activity was found to be 98.5%. Use of MNPs for the immobilization increased the reusability of enzyme with retained activity up to 82% after 5th cycle.

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