Extraction of phenolic compounds from rice husk via ethanol-water-modified supercritical carbon dioxide
Document Type
Article
Publication Date
3-2023
Keywords
Supercritical carbon dioxide, Ethanol, Water, Extraction, Rice husk, Phenolic compounds
Abstract
Rice husk, a rice processing byproduct generated in large quantities (∼20% of the grain weight), creates a major disposal problem for the rice industry. However, rice husk contains high-value bioactive compounds that can provide potential health benefits. The objective of this study was to extract high-value phenolic compounds from rice husk using supercritical carbon dioxide (SC–CO2) technology. In this study, the effects of different extraction conditions, namely, temperature (40 and 60 °C), pressure (30 and 40 MPa), and ethanol concentration (15 and 25%, w/w) on the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity (AA) were investigated. The extraction of phenolic compounds was also studied using different SC-CO2 modifiers, i.e., ethanol and ethanol-water. The highest TPC, TFC, and AA were achieved with 30 MPa, 60 °C, and 25% ethanol-water (50%, v/v) cosolvent mixture as 1.29 mg gallic acid equivalent (GAE)/g, 0.40 mg catechin equivalent (CE)/g, and 0.23 mg Trolox equivalent (TE)/g, respectively. Increasing water content up to 50% (v/v) in the cosolvent significantly improved the extraction yield. p-Coumaric, ferulic, and syringic acids were the predominant phenolic acids in the extracts obtained by cosolvent-modified SC-CO2 and methanol extractions. In addition, ethanol-water-modified SC-CO2 increased rice husk's porosity, which could be a potential pretreatment to enhance cellulose extraction. Thus, ethanol-water-modified SC-CO2 can be utilized to recover polar bioactive compounds from food processing byproducts for developing functional foods while eliminating the use of toxic organic solvents.
Citation
Kaur, S., & Ubeyitogullari, A. (2023). Extraction of phenolic compounds from rice husk via ethanol-water-modified supercritical carbon dioxide. Heliyon, 9 (3) https://doi.org/https://doi.org/10.1016/j.heliyon.2023.e14196
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Comments
This article was published with support from the Open Access Publishing Fund administered through the University of Arkansas Libraries.