title: Rapid methods for extracting and quantifying phenolic compounds in citrus rinds.
abstract: Conventional methods for extracting and quantifying phenolic compounds in citrus rinds are time consuming. Rapid methods for extracting and quantifying phenolic compounds were developed by comparing three extraction solvent combinations (80:20 v/v ethanol:H2O; 70:29.5:0.5 v/v/v methanol:H2O:HCl; and 50:50 v/v dimethyl sulfoxide (DMSO):methanol) for effectiveness. Freeze-dried, rind powder was extracted in an ultrasonic water bath at 35°C for 10, 20, and 30 min. Phenolic compound quantification was done with a high-performance liquid chromatography (HPLC) equipped with diode array detector. Extracting with methanol:H2O:HCl for 30 min resulted in the optimum yield of targeted phenolic acids. Seven phenolic acids and three flavanone glycosides (FGs) were quantified. The dominant phenolic compound was hesperidin, with concentrations ranging from 7500 to 32,000 μg/g DW. The highest yield of FGs was observed in samples extracted, using DMSO:methanol for 10 min. Compared to other extraction methods, methanol:H2O:HCl was efficient in optimum extraction of phenolic acids. The limit of detection and quantification for all analytes were small, ranging from 1.35 to 5.02 and 4.51 to 16.72 μg/g DW, respectively, demonstrating HPLC quantification method sensitivity. The extraction and quantification methods developed in this study are faster and more efficient. Where speed and effectiveness are required, these methods are recommended.
authors.affiliation: Department of Crop Science School of Agricultural, Earth and Environmental Sciences University of KwaZulu-Natal Private Bag X01, Scottsville 3209 Pietermaritzburg South Africa.
authors.forename: Lembe Samukelo
authors.initials: LS
authors.lastname: Magwaza
authors.affiliation: Postharvest Technology Research Laboratory Department of Horticultural Science Stellenbosch University Stellenbosch 7602 South Africa; Postharvest Technology Research Laboratory Department of Food Science South African Research Chair in Postharvest Technology Stellenbosch University Stellenbosch 7602 South Africa.
authors.forename: Umezuruike Linus
authors.initials: UL
authors.lastname: Opara
authors.affiliation: Citrus Research International Department of Horticultural Science Stellenbosch University Stellenbosch 7602 South Africa.
authors.forename: Paul J R
authors.initials: PJ
authors.lastname: Cronje
authors.affiliation: Plant Science Laboratory Cranfield University Bedfordshire MK43 0AL UK.
authors.forename: Sandra
authors.initials: S
authors.lastname: Landahl
authors.affiliation: Plant Science Laboratory Cranfield University Bedfordshire MK43 0AL UK.
authors.forename: Jose Ordaz
authors.initials: JO
authors.lastname: Ortiz
authors.affiliation: Plant Science Laboratory Cranfield University Bedfordshire MK43 0AL UK.
authors.forename: Leon A
authors.initials: LA
authors.lastname: Terry
keywords: Extraction method; flavanone glycosides; phenolic acids; phenolics