Recovery of antioxidative phenolic compounds by the valorization of rice biomass under the influence of lignocellulolytic enzymes

Abstract

The present work aimed to optimize the recovery of antioxidative phenolic compounds from steam treated and untreated rice biomass (rice bran and rice straw) by the influence of lignocellulolytic enzymes of Burkholderia sp SMB1. The optimization of extraction was carried out by response surface methodology targeting to maximize phenolic release. These compounds were separated from the extracts using charcoal and un-utilized hydrolysed rice bran wastes and analysed for antioxidant properties. 10% (w/v) rice biomass with 60 mg of enzyme loadings (mg of protein in crude enzyme extract) at 40 °C, pH 7 for 30 min. Ferulic acid, gallic acid, coumaric acid, syringic acid, caffeic acid, epicatechin and kaemferol were identified by HPLC in both rice biomass extracts. Maximum total phenolics (83.35 mg GAE/100 g), total flavonoid content (16.89 mg/100 g QE), total tannin content (78.69 mg/100 g TAE) and antioxidant properties viz., 87.68% for ABTS, 77.11% for DPPH and 0.82 absorbance for FRAP was obtained for steam treated rice bran followed by rice straw. This work signifies the biomass transformation into phenolics possessing antioxidant nature under simple extraction process. It not only favours waste management process but also increases the income to agriculture sector.

Keywords:

• Rice biomass
• Burkholderia sp SMB1
• lignocellulolytic enzymes
• phenolics extraction
• natural antioxidants

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors are thankful to Department of Biotechnology (DBT), New Delhi and University Grants Commission (UGC SAP DRS-II), New Delhi, Government of India, for funding this work in the form of project. The author Kumar Shankar also acknowledge CSIR, New Delhi, India for funding in the form of CSIR-SRF direct (File No: 09/450(0046)/2020-EMR-I).