Recovery of polyphenols from agro-industries wastes: Extraction studies

Recovery of polyphenols from agro-industries wastes: preliminary extraction studies P. Tapia*, M.F. Montenegro*, M. Reig*, X. Vecino*, C. Valderrama*, J.L. Cortina*,**, M. Granados***, X. Saurina*** INTRODUCTION Wastes generated during production of agro-food products, such as, fruits and vegetables juices, olive oil or wine are rich in bioactive compounds like polyphenols. These biocompounds have antioxidant properties and can be used in many valuable applications in the pharmaceutical, cosmetic and food industries, and thus their recovery from agro-food wastes is interesting (Kammerer et al.,2014). To speed up and/or to increase the efficiency of the polyphenols extraction, extraction techniques using supplementary energy can be advantageous (Rosello-Soto et al.,2015; Souilem et al.,2017). In this work the application of ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE) have been studied for the extraction of polyphenols from 4agro-food industry wastes, i.e. orange peel and seeds, spinach leaves, olive wastes and lees. MATERIALS AND METHODS To optimize UAE and MAE, factorial experimental designs were applied.For UAE the factors considered were %ethanol and % HCl for afixed extraction time of 30 minutes. For MAE, %ethanol, time and also temperature were considered. *Chemical Engineering Department, UPC-Barcelona TECH; Barcelona Research Center for Multiscale Science and Engineering, C/ Eduard Maristany 10-14, Campus Diagonal-Besòs, 08930 Barcelona, Spain. Email: [email protected] **CETAQUA, Carretera d'Esplugues, 75, 08940 Cornellà de Llobregat, Spain. ***Chemical Engineering and Analytical Chemistry Department, University of Barcelona, Martí iFranquès 1, 08028 Barcelona, Spain. Email: xavi.saur[email protected] Table 1. Experimental design for UAE and MAE conditions. Technique Factor Level UAE Ethanol (% v/v) 40, 60, 80 HCl (% v/v) 0.0, 0.1, 0.5 Time (min) 30 MAE Ethanol (% v/v) 0, 40, 60 Temperature (ºC) 60, 90, 120 Time (min) 5, 15, 30 The extracts were further analyzed by high performance liquid chromatography (HPLC) with diode array detection at the following conditions: -Kinetx C18 column (100 mm x 4.6 mm, 2.6 μm) -Mobile phases: A: 0.1% formic acid in water, and B: acetonitrile -Gradient elution mode -Flow rate: 0.4 mL/min -Injection volume: 5 μL -Run time:39 min -Detection at 280 nm (Raja et al., 2014) HPLC Agilent 1100 Sample waste Weight 1 g Add solvent: a mixture ratio ethanol/H2O /HCl Extraction technique: UAE and MAE Centrifuge: 15 min, 3500 rpm Filtration: 0.45 µm nylon filter Quantification by HPLC Figure 1 Polyphenols extraction process from orange peel and seeds, spinach leaves, olive wastes and lees. RESULTS AND DISCUSSION The maximum polyphenol extraction was obtained by amixture containing ethanol/H2O/HCl 60/39.9/0.1 (v/v/v). This mixture provided satisfactory results in the extraction of polyphenols from the assayed matrices, using either UAE (during an extraction time of 30 minutes) or MAE (establishing an extraction time of 15 minutes and atemperature of 90ºC). Overall, the UAE process provides similar results to MAE, except for the orange matrix.In this case, total polyphenol extraction efficiency using MAE was about 4times higher than that obtained by UAE. On the other hand, some polyphenols degradation in lees and spinach extracts, when using MAE above 90°C, was observed.As amatter of example, Figure 2shows the chromatograms of spinach extracts obtained by MAE at 90°C and 120°C. CONCLUSIONS Amixture containing low acid concentration (0.1%) and 60%ethanol, has shown good performance for polyphenols extraction.For spinach waste, olive pomace,and lees UAE technique provides similar results than MAE, whereas for orange waste MAE shows better extraction results. REFERENCES •Kammerer D.R., Kammerer, J., Valet R., Carle R. 2014 Recovery of polyphenols from the by-products of plant food processing and application as valuable food ingredients. Food Research International,65(Part A), 2-12. •Raja M., Hernandez-Revelles J., Hernandez-Cassou S., Saurina J. 2014 Determination of polyphenols in the pear pulp matrix by solvent extraction and liquid chromatography with UV-Vis detection, Analytical Methods, 6, 9769-9776. •Rosello-Soto E., Galanakis C.M., Brncic M., Orlien V., Trujillo F.J., Mawson, R., Knoerzer K., Tiwari B.K., Barba, F. J. 2015 Clean recovery of antioxidant compounds from plant foods, by-products and algae assisted by ultrasounds processing.Modeling approaches to optimize processing conditions.Trends in Food Science &Technology, 42(2), 134-149. •Souilem S., Fki I., Kobayashi I., Khalid N., Neves M.A., Isoda H., Sayadi S., Nakajima M. 2017 Emerging Technologies for Recovery of Value-Added Components from Olive Leaves and Their Applications in Food/Feed Industries.Food and Bioprocess Technology,10(2), 229-248. ACKNOWLEDGEMENTS This research was supported by Waste2Product project (ref.CTM2014-57302-R) and R2MIT project (ref.CTM2017-85346-R) financed by the Spanish Ministry of Economy and Competitiveness (MINECO) and the Catalan Government (ref.2017-SGR-312), Spain.As well, Paulina Tapia thanks CONACYT for her pre-doctoral grant and Xanel Vecino thanks MINECO for her Juan de la Cierva contract (ref.IJCI-2016-27445). Figure 2.HPLC-UV chromatograms of spinach leaves extracts obtained by MAE at two temperature conditions.Extraction solvent:Ethanol/H2O/HCl 60/39.9/0.1 (v/v/v). Extraction time:15 min.