Comparison of Different Extraction Methods for the Recovery of Olive Leaves Polyphenols

Ana Dobrinčić,Ivona Elez Garofulić,Lucija Tuđen,Verica Dragović-Uzelac,Maja Repajić,Branka Levaj

doi:10.3390/pr8091008

Ana Dobrinčić, Ivona Elez Garofulić + Show 4 more

Open Access

https://doi.org/10.3390/pr8091008

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Journal: Processes	Publication Date: Aug 19, 2020
Citations: 67	License type: CC BY 4.0

Affiliation: University of Zagreb

Abstract

In the present study, advanced extraction techniques, microwave (MAE), ultrasound (UAE), and high pressure (HPAE)-assisted extraction, were applied to improve extraction efficiency of olive (Olea europaea L.) leaves polyphenols. The effect of sample mass (1.5 and 3 g), MAE—time (2, 8.5, and 15 min) and temperature (45 and 80 °C), UAE—time (7, 14, and 21 min) and amplitude (50 and 100%) and HPAE—time (1, 5.5, and 10 min) and pressure (300 and 500 MPa) on the concentration of each analyzed polyphenol compound was examined. Identified polyphenols were oleuropein, hydroxytyrosol, chlorogenic acid, caffeic acid, verbascoside, and rutin. All three advanced extraction techniques yielded higher content of total polyphenols when compared to the conventional heat-reflux extraction (CE) along with a significant reduction of extraction time from 60 (CE) to 2, 21, and 5.5 min in MAE, UAE, and HPAE, respectively. The most intensive values of tested parameters in each technique were the ones that promoted cell wall disruption, e.g., temperature of 80 °C in MAE, 100% amplitude in UAE and 500 MPa in HPAE. MAE and UAE were more efficient in total polyphenols’ recovery than HPAE.

Highlights

Olive (Olea europaea L.) is one of the most important crops in the Mediterranean region primarily used for oil production, where during pruning of the olive tree a significant amount of by-products are accumulated
Olive leaves extracts obtained using MAE, ultrasound-assisted extraction (UAE), and high-pressure-assisted extraction (HPAE) consisted of HT, chlorogenic acid (CA), caffeic acid (CF), VB, RT and
Except for HT which was not influenced by concentration of 74.81 (MAE), 74.27 (UAE), and 69.23 mg g−1 (HPAE)

Summary

Introduction

Olive (Olea europaea L.) is one of the most important crops in the Mediterranean region primarily used for oil production, where during pruning of the olive tree a significant amount of by-products (leaves and branches) are accumulated. Olive leaves are considered as an inexpensive, renewable, and abundant source of polyphenols [1] and it has been found that olive leaves extract (OLE) has antioxidative, anti-inflammatory, and antimicrobial properties against bacteria and fungi, and shows anti-viral properties against several different viruses [2]. Several studies have reported the individual phenolic profile of olive leaves showing hydroxytyrosol, rutin, verbascoside, luteolin-7-glucoside, luteolin-40 -glucoside, oleuropein, oleuropein aglycone, and ligstroside aglycone being the most abundant among the large number of diverse phenolic compounds identified [3,4,5,6,7,8]. OLE polyphenolic content highly depends upon a plant’s geographical origin and cultivar, as well as the efficiency of the applied extraction technique.

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