title: Optimisation and validation of the microwave-assisted extraction of phenolic compounds from rice grains.
abstract: A new microwave-assisted extraction (MAE) method has been investigated for the extraction of phenolic compounds from rice grains. The experimental conditions studied included temperature (125-175°C), microwave power (500-1000W), time (5-15min), solvent (10-90% EtOAc in MeOH) and solvent-to-sample ratio (10:1 to 20:1). The extraction variables were optimised by the response surface methodology. Extraction temperature and solvent were found to have a highly significant effect on the response value (p<0.0005) and the extraction time also had a significant effect (p<0.05). The optimised MAE conditions were as follows: extraction temperature 185°C, microwave power 1000W, extraction time 20min, solvent 100% MeOH, and solvent-to-sample ratio 10:1. The developed method had a high precision (in terms of CV: 5.3% for repeatability and 5.5% for intermediate precision). Finally, the new method was applied to real samples in order to investigate the presence of phenolic compounds in a wide variety of rice grains.
authors.affiliation: Department of Food and Agricultural Product Technology, Faculty of Agricultural Technology, Gadjah Mada University, Jalan Flora, 55284 Yogyakarta, Indonesia; Department of Analytical Chemistry, Faculty of Sciences, University of Cadiz, Campus de Excelencia Internacional Agroalimentario (CeiA3), Spain.
authors.forename: W
authors.initials: W
authors.lastname: Setyaningsih
authors.affiliation: Department of Analytical Chemistry, Faculty of Sciences, University of Cadiz, Campus de Excelencia Internacional Agroalimentario (CeiA3), Spain.
authors.forename: I E
authors.initials: IE
authors.lastname: Saputro
authors.affiliation: Department of Analytical Chemistry, Faculty of Sciences, University of Cadiz, Campus de Excelencia Internacional Agroalimentario (CeiA3), Spain. Electronic address: miguel.palma@uca.es.
authors.forename: M
authors.initials: M
authors.lastname: Palma
authors.affiliation: Department of Analytical Chemistry, Faculty of Sciences, University of Cadiz, Campus de Excelencia Internacional Agroalimentario (CeiA3), Spain.
authors.forename: C G
authors.initials: CG
authors.lastname: Barroso
mesh_terms: D005591:Chemical Fractionation / Q000295:instrumentation / Q000379:methods*; D008872:Microwaves; D012275:Oryza / Q000737:chemistry*; D010636:Phenols / Q000032:analysis / Q000302:isolation & purification*; D010936:Plant Extracts / Q000032:analysis / Q000302:isolation & purification*; D012639:Seeds / Q000737:chemistry
chemical_list: D010636:Phenols; D010936:Plant Extracts
keywords: HPLC-PDA; Microwave-assisted extraction; Phenolic compounds; Rice grains