Supercritical CO2 Extraction of Phytocompounds from Olive Pomace Subjected to Different Drying Methods.

Graziana Difonzo,Federica Massari,Antonella Aresta,Carlo Zambonin,Carmine Summo,Pietro Cotugno,Michele Faccia,Antonella Pasqualone,Roberta Ragni,Francesco Caponio,Giacomo Squeo

doi:10.3390/molecules26030598

Abstract

Olive pomace is a semisolid by-product of olive oil production and represents a valuable source of functional phytocompounds. The valorization of agro-food chain by-products represents a key factor in reducing production costs, providing benefits related to their reuse. On this ground, we herein investigate extraction methods with supercritical carbon dioxide (SC-CO2) of functional phytocompounds from olive pomace samples subjected to two different drying methods, i.e., freeze drying and hot-air drying. Olive pomace was produced using the two most common industrial olive oil production processes, one based on the two-phase (2P) decanter and one based on the three-phase (3P) decanter. Our results show that freeze drying more efficiently preserves phytocompounds such as α-tocopherol, carotenoids, chlorophylls, and polyphenols, whereas hot-air drying does not compromise the β-sitosterol content and the extraction of squalene is not dependent on the drying method used. Moreover, higher amounts of α-tocopherol and polyphenols were extracted from 2P olive pomace, while β-sitosterol, chlorophylls, and carotenoids were more concentrated in 3P olive pomace. Finally, tocopherol and pigment/polyphenol fractions exerted antioxidant activity in vitro and in accelerated oxidative conditions. These results highlight the potential of olive pomace to be upcycled by extracting from it, with green methods, functional phytocompounds for reuse in food and pharmaceutical industries.

Highlights

The growing interest in the use of natural functional molecules for consumer purposes in view of human health and environmental protection has favored a series of research studies on the extraction of various phytocompounds from natural raw plants
SC-CO2 extraction was carried out according to a method reported in the literature for recovery of lipophilic compounds from residual olive husk by supercritical fluids [23,42]
Two different types of olive pomace were subjected to supercritical fluid extraction, being considered a promising source of interesting compounds, such as tocopherols, β-sitosterol, squalene, chlorophylls, and carotenoids

Summary

Introduction

The growing interest in the use of natural functional molecules for consumer purposes in view of human health and environmental protection has favored a series of research studies on the extraction of various phytocompounds from natural raw plants. Olive pomace includes a variable small portion of residual oil that can be recovered by solvent extraction after drying the olive pomace [7]. This recovery process generates another waste, known as dry olive cake, suitable as a fuel [3,7]. The distribution in olive and waste streams (olive mill wastewater and pomace) of predominant lipophilic bioactive molecules, such as squalene, β-sitosterol, and α-tocopherol, has been reported in the literature [10], as well as the loss of lipophilic phytocompounds during the industrial virgin olive oil production [11]

Methods

Results

Conclusion