Supercritical Carbon Dioxide Extraction of Phenolic Compounds from Potato (Solanum tuberosum) Peels

Micael De Andrade Lima,Afroditi Chatzifragkou,Rafaela Andreou,Dimitris Charalampopoulos

doi:10.3390/app11083410

Abstract

In the last three decades, greener technologies have been used, aiming at extracting phenolic compounds from vegetable matrices due to the inherent advantages compared to organic solvent-based methodologies. In this work, supercritical CO2 was investigated for recovering phenolic acids from potato peels. Following screening runs for assessing the significant extraction parameters, a Central Composite Design of Experiments was carried out aiming at process optimization, with methanol concentration (MeOH, %) and CO2 flow rate (qCO2, g/min) as independent variables. Both parameters were deemed to impart a significant effect on the final response. Although the major phenolic acid in potato peels is chlorogenic acid (CGA), the main compound extracted was caffeic acid (CFA), present at a concentration of 0.75 mg/g dry peel in the extracts. The optimum extraction conditions were 80 °C, 350 bar, MeOH 20%, and flow rate of 18.0 g/min, which enabled a total phenolic recovery of 37% and a CFA recovery of 82%. The antioxidant activity of the supercritical fluid extraction (SFE) extracts was also measured, with the highest scavenging capacity reaching 73%. The need for using mixtures of water and organic solvents as co-solvents in SFE to enable CGA recovery seems necessary, possibly due to its better dissolution in aqueous solutions than in pure solvents.

Highlights

Potato peels are one of the most common vegetable by-products in Europe and are considered a zero-value waste in potato processing plants [1]
Non-conventional technologies, such as microwave, ultrasound, enzyme, and electric field-assisted extractions, as well as extractions via pressurized liquids, subcritical water, and supercritical fluids, have been able to circumvent many of these drawbacks and a growing number of works from the literature have reported on their application for extracting phenolic compounds from a variety of matrices [12], including potato peels [11,13,14,15,16,17,18]
Apart from starch, which is made up of glucose monomers, potato peels contain other carbohydrates such as cellulose, hemicellulose, and pectin. This explains the difference between the monomeric sugar profile observed in the samples of peels and that found in the flesh

Summary

Introduction

Potato peels are one of the most common vegetable by-products in Europe and are considered a zero-value waste in potato processing plants [1]. Phenolics have shown a plethora of benefits to the human health, such as antioxidant [7], antimicrobial, antivirus [8], and even anti-parasite properties [9], among others. Given such potential, the extraction of these compounds for valorizing an otherwise zero-value matrix is highly interesting from an industrial perspective [6,10]. Non-conventional technologies, such as microwave-, ultrasound-, enzyme-, and electric field-assisted extractions, as well as extractions via pressurized liquids, subcritical water, and supercritical fluids, have been able to circumvent many of these drawbacks and a growing number of works from the literature have reported on their application for extracting phenolic compounds from a variety of matrices [12], including potato peels [11,13,14,15,16,17,18]

Objectives

Methods

Results

Conclusion