title: Bio-refinery of orange peels waste: a new concept based on integrated green and solvent free extraction processes using ultrasound and microwave techniques to obtain essential oil, polyphenols and pectin.
abstract: In this study, extraction of essential oil, polyphenols and pectin from orange peel has been optimized using microwave and ultrasound technology without adding any solvent but only "in situ" water which was recycled and used as solvent. The essential oil extraction performed by Microwave Hydrodiffusion and Gravity (MHG) was optimized and compared to steam distillation extraction (SD). No significant changes in yield were noticed: 4.22 ± 0.03% and 4.16 ± 0.05% for MHG and SD, respectively. After extraction of essential oil, residual water of plant obtained after MHG extraction was used as solvent for polyphenols and pectin extraction from MHG residues. Polyphenols extraction was performed by ultrasound-assisted extraction (UAE) and conventional extraction (CE). Response surface methodology (RSM) using central composite designs (CCD) approach was launched to investigate the influence of process variables on the ultrasound-assisted extraction (UAE). The statistical analysis revealed that the optimized conditions of ultrasound power and temperature were 0.956 W/cm(2) and 59.83°C giving a polyphenol yield of 50.02 mgGA/100 g dm. Compared with the conventional extraction (CE), the UAE gave an increase of 30% in TPC yield. Pectin was extracted by conventional and microwave assisted extraction. This technique gives a maximal yield of 24.2% for microwave power of 500 W in only 3 min whereas conventional extraction gives 18.32% in 120 min. Combination of microwave, ultrasound and the recycled "in situ" water of citrus peels allow us to obtain high added values compounds in shorter time and managed to make a closed loop using only natural resources provided by the plant which makes the whole process intensified in term of time and energy saving, cleanliness and reduced waste water.
authors.affiliation: Laboratoire des Sciences et Techniques de l'Environnement (LSTE), Ecole Nationale Polytechnique, 10 Avenue Hacène Badi, BP 182, El Harrach, 16200 Alger, Algeria.
authors.forename: Meryem
authors.initials: M
authors.lastname: Boukroufa
authors.affiliation: Laboratoire des Sciences et Techniques de l'Environnement (LSTE), Ecole Nationale Polytechnique, 10 Avenue Hacène Badi, BP 182, El Harrach, 16200 Alger, Algeria. Electronic address: chahrazed.boutekedjiret@g.enp.edu.dz.
authors.forename: Chahrazed
authors.initials: C
authors.lastname: Boutekedjiret
authors.affiliation: Avignon University, INRA, UMR408, GREEN Extraction Team, F-84000 Avignon, France.
authors.forename: Loïc
authors.initials: L
authors.lastname: Petigny
authors.affiliation: Avignon University, INRA, UMR408, GREEN Extraction Team, F-84000 Avignon, France.
authors.forename: Njara
authors.initials: N
authors.lastname: Rakotomanomana
authors.affiliation: Avignon University, INRA, UMR408, GREEN Extraction Team, F-84000 Avignon, France. Electronic address: farid.chemat@univ-avignon.fr.
authors.forename: Farid
authors.initials: F
authors.lastname: Chemat
mesh_terms: D005591:Chemical Fractionation / Q000379:methods*; D032084:Citrus sinensis / Q000737:chemistry*; D019649:Food Industry; D007220:Industrial Waste; D010368:Pectins / Q000737:chemistry*; D010938:Plant Oils / Q000737:chemistry*; D059808:Polyphenols / Q000737:chemistry*; D000069453:Ultrasonic Waves
chemical_list: D007220:Industrial Waste; D010938:Plant Oils; D059808:Polyphenols; D010368:Pectins
keywords: Bio-refinery; Essential oil; Green extraction; Microwave; Polyphenol; Ultrasound