title: An Optimised Aqueous Extract of Phenolic Compounds from Bitter Melon with High Antioxidant Capacity.
abstract: Bitter melon (Momordica charantia L.) is a tropical fruit claimed to have medicinal properties associated with its content of phenolic compounds (TPC). The aim of the study was to compare water with several organic solvents (acetone, butanol, methanol and 80% ethanol) for its efficiency at extracting the TPC from freeze-dried bitter melon powder. The TPC of the extracts was measured using the Folin-Ciocalteu reagent and their antioxidant capacity (AC) was evaluated using three assays. Before optimisation, the TPC and AC of the aqueous extract were 63% and 20% lower, respectively, than for the best organic solvent, 80% ethanol. However, after optimising for temperature (80 °C), time (5 min), water-to-powder ratio (40:1 mL/g), particle size (1 mm) and the number of extractions of the same sample (1×), the TPC and the AC of the aqueous extract were equal or higher than for 80% ethanol. Furthermore, less solvent (40 mL water/g) and less time (5 min) were needed than was used for the 80% ethanol extract (100 mL/g for 1 h). Therefore, this study provides evidence to recommend the use of water as the solvent of choice for the extraction of the phenolic compounds and their associated antioxidant activities from bitter melon.
authors.affiliation: School of Environmental and Life Sciences, University of Newcastle, Ourimbah, NSW 2258, Australia. sing.p.tan@uon.edu.au.
authors.forename: Sing Pei
authors.initials: SP
authors.lastname: Tan
authors.affiliation: Faculty of Bioscience Engineering, Ghent University Global Campus, Incheon 406-840, Korea. costas.stathopoulos@ghent.ac.kr.
authors.forename: Costas
authors.initials: C
authors.lastname: Stathopoulos
authors.affiliation: School of Environmental and Life Sciences, University of Newcastle, Ourimbah, NSW 2258, Australia. sophie.parks@dpi.nsw.gov.au.|Central Coast Primary Industries Centre, NSW Department of Primary Industries, Ourimbah, NSW 2258, Australia. sophie.parks@dpi.nsw.gov.au.
authors.forename: Sophie
authors.initials: S
authors.lastname: Parks
authors.affiliation: School of Environmental and Life Sciences, University of Newcastle, Ourimbah, NSW 2258, Australia. paul.roach@newcastle.edu.au.
authors.forename: Paul
authors.initials: P
authors.lastname: Roach
keywords: antioxidant capacity; aqueous extraction; bitter melon; organic solvents; phenolic compounds