Determination of phenolic compounds in strawberries (Fragaria ananassa Duch.) by high performance liquid chromatography with diode array detection

ANNA MARIA TAROLA; FRANCO VAN DE VELDE; LUCILLA SALVAGNI; RAFFAELLA PRETI

FOOD ANALYTICAL METHODS

SPRINGER

Lugar: Berlin; Año: 2013 vol. 6 p. 227 - 237

1936-9751

This paper describes an method for simultaneous identification and quantification ofphenolic compounds in strawberries followed by a reversed phase high performanceliquid chromatography HPLC with diode array detection.The studied phenolics wereflavonoids (flavonols: quercentin, rutin, and kaempferol; flavanols: catechin andepicatechin; anthocyanidins: cyanindin and pelargonidin) and phenolic acids(hydroxybenzoic acid derivatives: gallic and ellagic acids; hydroxycinnamic acidderivatives: ferulic, coumaric and cinnamic acids). The mobile phase consisted in agradient prepared from formic acid in water (2%, pH 3) and formic acid in methanol(2%, pH 3), flow rate 0.7 ml min-1 at 25°C. Analyses were performed, using methanolas extractant, before and after acid hydrolysis with the aim of determine free andconjugated phenolic compounds in strawberries. The acid hydrolysis conditions (6 molL-1 HCl, 50 min at 90°C) showed to be suitable both for phenolic standards andstrawberry extracts. Method validation, using phenolic standard solutions, included:linearity study, limits of detection and quantification, and calibration and analyticalsensitivity quantifications. Precision and accuracy were studied in strawberry extracts.The results indicate that the developed method was linear, sensible, precise andaccurate, and the convenience of methanol can substitute acetonitrile as the mostcommonly solvent used in HPLC. The method was employed for knowing the phenolicprofile in seven strawberry cultivars from Italy and Argentina; and besides, totalphenolic content was analyzed by Folin-Ciocalteu (F-C) method and the totalantioxidant activity was investigated using the ABTS method. Good correlations wereobserved among latter parameters and total phenolics obtained as the sum of eachphenolic compound analyzed by DAD-HPLC.