Comparison between different liquid-liquid and solid phase methods of extraction prior to the identification of the phenolic fraction present in olive oil washing wastewater from the two-phase olive oil extraction system

S Jiménez-Herrera,J M Ochando-Pulido,A Martínez-Ferez

doi:10.3989/gya.0225171

Abstract

Phenolic compounds from olive mill wastewater (OMW), are characterized by a strong antioxidant activity. At the same time, they represent an environmental problem because they are difficult to degrade. The purpose of this work was to identify these biologically active compounds in the OMW from two-phase olive oil production in order to convert a polluting residue into a source of natural antioxidants. After optimizing the extraction process of phenolic compounds using liquid-liquid extraction (LLE) and solid phase extraction (SPE) methods, it was determined that the most appropriate sequence comprised a previous centrifugation to remove the lipid fraction, followed by liquid extraction with ethyl acetate or SPE. The most important compounds identified in olive oil washing wastewater (OOWW) were tyrosol, hydroxytyrosol and succinic acid; whereas the ones in the wastewater derived from the washing of the olives (OWW) were cresol, catechol, 4-methylcatechol, hydrocinnamic acid and p-hydroxy-hydrocinnamic acid.

Highlights

Olive mill wastewater (OMW) generated in two-phase olive oil production consists of waste water derived from the washing of the olives (OWW) and wastewater that leaves the vertical centrifuge machines (OOWW)
The most important compounds found in olive oil washing wastewater (OOWW) were tyrosol, hydroxytyrosol and succinic acid, whereas the most interesting compounds found in olive washing water (OWW) were cresol, catechol, 4-methylcatechol, hydrocinnamic acid, p-hydroxy-hydrocinnamic acid
The goal of this work was to identify the polyphenols present in the wastewater generated from two-phase olive oil production, from the washing of the olives, OOWW, and from the vertical centrifugation, OWW, since it possesses antioxidant properties which are beneficial for health and industrial applications, whereas these effluents represent a serious environmental problem because these compounds are phytotoxic and difficult to degrade

Summary

Introduction

Olive mill wastewater (OMW) generated in two-phase olive oil production consists of waste water derived from the washing of the olives (OWW) and wastewater that leaves the vertical centrifuge machines (OOWW). The OOWW generated in the two-phase olive oil production process is the major waste product of this industry and one of the most serious environmental problems in Mediterranean countries. Portugal, Greece and the North African countries Syria, Algeria, Turkey, Morocco, Tunisia, Libya, and Lebanon are the largest producers in the world. Other countries such as France, Serbia and Montenegro, Macedonia, Cyprus, Egypt, Israel, and Jordan produce a considerable annual amount of olive oil according to the data registered by International Olive Oil Council (IOOC, 2016). The current growth of the olive oil production sector is parallel to the development and modernization of olive oil factories, due to the greater global demand of olive oil

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