Ciência e Tecnologia de Alimentos ISSN: 0101-2061 [email protected] Sociedade Brasileira de Ciência e Tecnologia de Alimentos Brasil LEOUIFOUDI, Inass; ZYAD, Abdelmajid; AMECHROUQ, Ali; OUKERROU, Moulay Ali; MOUSE, Hassan Ait; MBARKI, Mohamed Identification and characterisation of phenolic compounds extracted from Moroccan olive mill wastewater Ciência e Tecnologia de Alimentos, vol. 34, núm. 2, abril-junio, 2014, pp. 249-257 Sociedade Brasileira de Ciência e Tecnologia de Alimentos Campinas, Brasil Available in: http://www.redalyc.org/articulo.oa?id=395940095005 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative Food Science and Technology ISSN 0101-2061 DDOI http://dx.doi.org/10.1590/fst.2014.0051 Identification and characterisation of phenolic compounds extracted from Moroccan olive mill wastewater Inass LEOUIFOUDI1,2*, Abdelmajid ZYAD2, Ali AMECHROUQ3, Moulay Ali OUKERROU2, Hassan Ait MOUSE2, Mohamed MBARKI1 Abstract Olive mill wastewater, hereafter noted as OMWW was tested for its composition in phenolic compounds according to geographical areas of olive tree, i.e. the plain and the mountainous areas of Tadla-Azilal region (central Morocco). Biophenols extraction with ethyl acetate was efficient and the phenolic extract from the mountainous areas had the highest concentration of total phenols’ content. Fourier-Transform-Middle Infrared (FT-MIR) spectroscopy of the extracts revealed vibration bands corresponding to acid, alcohol and ketone functions. Additionally, HPLC-ESI-MS analyses showed that phenolic alcohols, phenolic acids, flavonoids, secoiridoids and derivatives and lignans represent the most abundant phenolic compounds. Nüzhenide, naringenin and long chain polymeric substances were also detected. Mountainous areas also presented the most effective DPPH scavenging potential compared to plain areas; IC50 values were 11.7 ± 5.6 µg/ml and 30.7 ± 4.4 µg/ml, respectively. OMWW was confirmed as a rich source of natural phenolic antioxidant agents. Keywords: phenolic compounds; olive mill wastewater; HPLC-ESI-MS; antioxidant activity. 1 Introduction The olive oil industry in the Mediterranean region rejects (Borja et al., 1997; Ergun Ergül et al., 2009; Fiorentino et al., annually up to 8.4 million m3 of OMWW, of which 250 000 2003; Davies et al., 2004). Apart from water (83-92%), the main m3 are produced in Morocco (Ben Sassi et al., 2006). This has components of OMWW are phenolic compounds, sugars and become a major environmental problem in the countries of organic acids. OMWW contains also valuable resources such as this region. Tadla-Azilal is an important olive oil production mineral nutrients, especially potassium, which could potentially region of Morocco and the resulting OMWW was directly be reused as a fertilizer (Aranda et al., 2007; Dermeche et al., discharged in soils without any treatment, thus causing a 2013). Thus, the scientific community is still in search of effective negative environmental impact (Ruiz-Rodriguez et al., 2010). processes for reducing these contaminants (Mantzavinos & OMWW is a mildly acidic, red-to-black coloured, liquid of Kalogerakis, 2005). In this way, several techniques have been high conductivity. It is particularly rich in organic matter and used to recover phenolic compounds from olive by-products, toxic fatty acids (Mekki et al., 2006; Sayadi et al., 2000). The including enzymatic preparation, solvent extraction, membrane high-molecular-weight polyphenols, similar in structure to separation, centrifugation, and chromatographic procedures lignin, give OMWW their characteristic brownish black colour (Dermeche et al., 2013). Solvent extraction is the most (Assas et al.., 2002; D’Annibale et al., 2004). Moreover, the high commonly employed technique to extract phenolic compounds, pollution potential of this effluent is commonly attributed to its and ethyl acetate is the most effective solvent for the treatment high phenolic content of monomeric phenols, toxic to plants, of OMWW under acidic conditions (Allouche et al., 2004). water and some microorganisms (Capasso et al., 1992). OMWW Different processing practices such as biological, chemical and may contains up to 10 g of phenols per liter (D’Annibale et al., physical methods have been used for the valorisation of olive 1998) while in the European Union, the accepted maximum residues while the development of these processes is deterred phenol concentration in wastewaters is 1 mg/L (Urban waste by their expensive costs. Furthermore, the renewed interest water treatment Directive 91/271/EEC) (European Commission, in such natural products has been supported by advances in 1991). Therefore, environmental survey authorities encourage chromatographic and spectroscopic techniques that have greatly the producers to change their production systems. However, facilitated drug discovery from plants (Obied et al., 2005). OMWW can be considered as a rich source of natural antioxidant phenolic compounds 100 fold concentrated than The aim of the present work was to identify and quantify in olive oil (Lesage-Meessen et al., 2001). Its composition the phenolic compounds, occurring in Moroccan OMWW varies both qualitatively and quantitatively according to originating from different areas, in view to understanding the olive variety, climate conditions, cultivation practices, their molecular bioactivities of further applications such as the olive storage time, and the olive oil extraction process antioxidant potentialities. Received 12 Dec., 2013 Accepted 21 Apr., 2014 (006240) 1 Transdisciplinary Team of Analytical Science for Sustainable Development, Faculty of Science and Technologies, Sultan Moulay Slimane University, Beni Mellal, Morocco 2 Laboratory of Biological Engineering, Faculty of Science and Technologies, Sultan Moulay Slimane University, Beni Mellal, Morocco, e-mail: [email protected] 3 Laboratory of Molecular Chemical and Natural Substances, Faculty of Science, Meknes, Morocco *Corresponding author Food Sci. Technol, Campinas, 34(2): 249-257, Apr.-June 2014 249 Phenolic profile of Moroccan olive mill wastewater extracts 2 Materials and methods 2.5 Middle Infrared spectroscopy analysis FT-MIR spectra of duplicate samples were obtained using 2.1 Chemicals a Bruker Vector 22 spectrometer possessing an integrated All solvents and chemicals were of HPLC grade and were Michelson interferometer and Opus 5.5 software. The measurements were obtained with crude samples deposited on obtained from Sigma Chemical Co. Saint Quentin (France). an attenuated reflection cell equipped with a diamond crystal. The generated spectra showed wavenumbers ranging between 2.2 Samples 400 and 4000 cm–1. Four OMWW samples were obtained as a liquid by- product (vegetation waters) by discontinuous three-phase olive 2.6 HPLC/ESI-MS analyses (High performance liquid processing mill and conserved at 4 °C. Samples were generated chromatography/Electro-Spray Ionization-Mass from Moroccan Picholine olives variety (Moroccan Picholine Spectrometry) olive variety was identified and authenticated by Pr. A. Boulli, HPLC–MS analyses were performed at 279 nm and 30°C Department of Biology, Sultan Moulay Slimane University, using a RP C18 column (150 × 4.6) × 5 µm possessing a Thermo and stored as a voucher specimen in the Faculty of Science Fisher apparatus equipped by a Surveyor quaternary pump and Technologies, Beni Mellal, Morocco). The studied samples coupled to a PDA detector (diode array detector: 200-600 nm) were collected at the end of the olive harvest season (January and an LCQ Advantage (ESI) ion trap mass spectrometer to March 2010) – at the maturation stage of red-black olives (Thermo Finnigan, San Jose, CA). The injected volume was from four areas of Tadla-Azilal region (central Morocco): Beni 20 µL. The mobile phase (0.5 mL/min) consisted of solvent A Mellal and Krazza (for plain areas samples), Azilal and Afourar (water +0.05% Trifloroacetic acid) and solvent B (Acetonitrile (for mountainous areas samples). +0.05% methanol). The six-step gradient was applied, for a total run time of 76 min, as follows: Starting from 80% solvent A and 20% solvent B increasing to 30% solvent B over 30 min, then 2.3 Extraction of phenolic compounds isocratic for 10 min, increased to 30% solvent B over 10 min, to The procedure was carried out using the analytical 40% over 30 min and to 20% solvent B over 2 min, and finally methodology described by De Marco et al. (2007) with isocratic for 4 min. ESI ionization conditions were spray voltage some modifications. The Samples were washed with hexane 4 KV, capillary 350°C, 14 V. Pure nitrogen was the sheath gas and pure helium was the collusion gas. The full scan mass data m/z [1:1, (v/v)] in order to remove the lipid fraction: 45 ml of was obtained in negative mode and ranged from 100 to 2000 Da. OMWW were mixed with 45 mL of hexane; the mixture was shaken and then centrifuged during 15 min at 4000 rpm. The 2.7 Antioxidant activity phases were separated and the washing was repeated successively two times. Extraction of phenolic compounds was then carried The antioxidant activity was performed using the DPPH out with ethyl acetate: 100 mL of OMWW samples, preventively (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay. The washed, were mixed with 100 mL of ethyl acetate; the mixture