Evaluation of solvent and temperature effect on green accelerated solvent extraction (ASE) and UHPLC quantification of phenolics in fresh olive fruit (Olea europaea)

Abstract

A green ASE (accelerated solvent extraction) with a shorter UHPLC (ultra-high performance liquid chromatography) method was developed for simultaneous determination of phenolics. High extract yield (130 mg/g) was observed for water at 100 °C in a short time of 19.5 min using 33.5 mL solvent whereas, UHPLC showed more phenolics of GA (gallic acid), QT (quercetin), LT (luteolin) in ACE (acetone) and RT (rutin) in EtOH (ethanol) solvent at 60 °C. The binary solvent system of ACE: EtOH (1:1) at 60 °C was optimized as extraction set. UHPLC runtime was 3 min with retention times of (min); 0.63 (GA), 0.97 (RT), 2.00 (QT) and 2.41 (LT). Average for phenolics (ppm) was, QT (10.91) > GA (7.33) > LT (4.10) > RT (3.90) whereas, Spanish whole green olive (SP2) showed more phenolics (20.72). Individual phenolic was, GA (47.06) > RT (26.21) > QT (19.34) > LT (6.18). Multivariate, K-mean and PCA (principal component analysis) for solvent*extract yield showed significant correlation and temperature showed no significant correlation for phenolics.

Keywords: ASE; Geographical origin; Olive; Phenolics; UHPLC.