title: Microwave pretreatment of defatted rice bran for enhanced recovery of total phenolic compounds extracted by subcritical water.
abstract: Enhanced recovery of total phenolics (TP) from defatted rice bran (DRB) subjected to prior microwave pretreatment was achieved by subcritical water extraction (SWE). The effects of microwave pretreatment temperature (60-100°C) and duration (0-30 min) were determined at raw material:water ratios (1:2 and 1:5) for SWE under fixed conditions. Optimal extraction was observed at 80°C (for 10 min, at a ratio of 1:2). With pretreatment carried out under these conditions, a shorter extraction time of 10 min was required for SWE at 200°C. Combining both optimized conditions, a TP yield of 190.4±3.3 mg/g of DRB was achieved, some 55% more than was found to be extractable from un-pretreated samples. The antioxidant activity of the extract was also greater, as indicated by a corresponding decrease in IC(50) from 38.8±0.4 to 27.7±0.5 μg/ml.
authors.affiliation: Chemical Engineering Research Unit for Value Adding of Bioresources, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand.
authors.forename: Piyaporn
authors.initials: P
authors.lastname: Wataniyakul
authors.forename: Prasert
authors.initials: P
authors.lastname: Pavasant
authors.forename: Motonobu
authors.initials: M
authors.lastname: Goto
authors.forename: Artiwan
authors.initials: A
authors.lastname: Shotipruk
mesh_terms: D008855:Microscopy, Electron, Scanning; D008872:Microwaves; D012275:Oryza / Q000737:chemistry*; D010636:Phenols / Q000032:analysis*; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D010636:Phenols; D014867:Water