Recovery of polyphenols from Olive Oil Mill wastes: a selective approach anchored to molecularly imprinting technology

Abstract

Olive oil is the main fat ingredient in the traditional Mediterranean diet mainly due to their antioxidant properties, the benefits associated with the regulation of cholesterol levels and prevention of cardiovascular diseases [1]. During the production of Virgin Olive Oil (VOO) large amounts of wastes, namely olive oil mill wastewaters (OMWW) are produced constituting a severe environmental problem in Mediterranean countries [2]. The main organic composition of OMWW comprises sugars, nitrogenous compounds, volatile acids, polyalcohols, pectins, fats and polyphenols [3]. The increasing interest on natural antioxidants combined with the recognized bioactivity of olive polyphenols makes OMWW very attractive as a potent source of natural antioxidants [1,4]. The valuable healthy benefits associated to polyphenols demonstrated by several studies that support their biological properties, in particular on the reduction of oxidative stress, has stimulated the research on technological strategies to extract and isolate those bioactive compounds. The development of analytical methodologies that enable the recovery of phenolic compounds from OMWW represents an analytical challenge mainly due to the inherent complexity of the matrix. In recent years, aiming to introduce reliable methodologies to achieve that purposes, several attempts have been performed mainly focused on extraction procedures, membrane separation, centrifugation and chromatography, being those techniques used individually or in a combined form [5] . Most of the analytical procedures developed have been mainly focused on the recovery of some polyphenols that possess a more powerful antioxidant, free radical scavenging, antimicrobial and anticarcinogenic properties, such as hydroxytyrosol, tyrosol, oleuropein and phenolic acids. Nowadays, the research on analytical methodologies based on molecular imprinted polymers (MIPs) for the selective recovery of phenolic compounds from OMWW has emerged as an innovative technology enabling the selective extraction and isolation of target molecules from the OMWW complex matrix which represents a valuable process in terms of further enhancing the waste valorization [6-8]. The scope of this review is to provide a general overview on the most used techniques for the recovery of polyphenols from olive oil mill waste with special emphasis on the application of MIP technology and also its potential impact on the field of olive oil waste valorization.