Valorisation of Exhausted Olive Pomace by an Eco-Friendly Solvent Extraction Process of Natural Antioxidants.

Irene Gómez-Cruz,Inmaculada Romero,Beatriz Gullón,Cristóbal Cara,Eulogio Castro

doi:10.3390/antiox9101010

Irene Gómez-Cruz, Inmaculada Romero + Show 3 more

Open Access

https://doi.org/10.3390/antiox9101010

Copy DOI

Abstract

Exhausted olive pomace (EOP) is the waste generated from the drying and subsequent extraction of residual oil from the olive pomace. In this work, the effect of different aqueous solvents on the recovery of antioxidant compounds from this lignocellulosic biomass was assessed. Water extraction was selected as the best option for recovering bioactive compounds from EOP, and the influence of the main operational parameters involved in the extraction was evaluated by response surface methodology. Aqueous extraction of EOP under optimised conditions (10% solids, 85 °C, and 90 min) yielded an extract with concentrations (per g EOP) of phenolic compounds and flavonoids of 44.5 mg gallic acid equivalent and 114.9 mg rutin equivalent, respectively. Hydroxytyrosol was identified as the major phenolic compound in EOP aqueous extracts. Moreover, these extracts showed high antioxidant activity, as well as moderate bactericidal action against some food-borne pathogens. In general, these results indicate the great potential of EOP as a source of bioactive compounds, with potential uses in several industrial applications.

Highlights

Lignocellulosic biomass is a renewable source of energy, biofuel and other valuable products that could contribute to reducing our intensive dependence on fossil fuels
This extractive content is high compared to other lignocellulosic biomasses, such as wheat straw [35], sugarcane bagasse [36], or Eucalyptus globulus [37], and is even higher than in other residues from the olive industry, such as olive stones or olive tree prunings
The performance of water extraction was comparable to that of organic solvents such as ethanol or acetone. This green solvent was selected for recovering bioactive compounds from exhausted olive pomace (EOP)

Summary

Introduction

Lignocellulosic biomass is a renewable source of energy, biofuel and other valuable products that could contribute to reducing our intensive dependence on fossil fuels. The estimated global annual production of lignocellulosic biomass is around 1 × 1011 tons [1]. Finding suitable feedstocks for biorefineries is essential, and agro-industrial lignocellulosic residues are expected to be the main feedstocks for such facilities, since woody materials compete with pulp production industries, and agricultural residues could contribute to maintaining nutrient levels and soil quality if returned to the field [1]. In this context, exhausted olive pomace (EOP) could be an interesting raw material for a biorefinery based on olive-derived residues. EOP is the waste generated in the olive pomace oil industry as a result of the drying and subsequent residual oil extraction from the olive pomace, which represents around 2% of its weight [3]

Objectives

Methods

Results

Conclusion