food and bioproducts processing 1 0 3 ( 2 0 1 7 ) 95–103 Contents lists available at ScienceDirect Food and Bioproducts Processing journal homepage: www.elsevier.com/locate/fbp Pectin recovery from sugar beet pulp enhanced by high-voltage electrical discharges Fouad Almohammed * , Mohamed Koubaa, Anissa Khelfa, Matheus Nakaya, Houcine Mhemdi, Eugène Vorobiev Sorbonne Universités, Université de Technologie de Compiègne, Laboratoire Transformations Intégrées de la Matière Renouvelable (UTC/ESCOM, EA 4297 TIMR), Centre de Recherche de Royallieu, CS 60319, 60203 Compiègne Cedex, France a r t i c l e i n f o Article history: Received 8 December 2016 Received in revised form 28 February 2017 Accepted 13 March 2017 Available online 23 March 2017 Keywords: Sugar beet pulp High-voltage electrical discharges Pectin Extraction diffusion coefficient Valorization a b s t r a c t This work discusses the valorization of sugar beet pulp (SBP) for pectin extraction using high-voltage electrical discharges (HVED) as a pre-treatment technology. The parameters of HVED (pulse amplitude U and number of pulses n) were varied. Better pre-treatment condi- tions were U = 40 kV and n = 100 giving a total energy consumption Q e = 76.2 kJ/kg. After the HVED pre-treatment, a subsequent acidified water extraction of pectin was carried out vary- ing the pH and temperature. Obtained results show the pectin yield increase from 42.6% for untreated SBP to 53.4% for HVED treated SBP at better extraction conditions (T = 90 ◦ C, pH = 2) and duration of one hour. Fourier transform infrared (FTIR) spectroscopy and gas chromatog- raphy mass spectrometry (GC–MS) techniques were used to characterize the pectin extracts. They showed similar functional groups and chemical composition between the standard of sugar beet pectin and the extracted molecules from untreated and HVED pretreated SBP. © 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. 1. Introduction Sugar beet pulp (SBP) is a residue recovered after sucrose extraction from sugar beet slices. It is compressed, dried and usually used for cattle feed due to its high content in fibers (Asadi, 2007). Several alter- native ways were recently proposed for the valorization of sugar beet pulp based on a biorefinery concept (Günan Yücel and Aksu, 2015; Hamley-Bennett et al., 2016; Vu ˇ curovi ´ c and Razmovski, 2012; Ward et al., 2015). Yapo et al. (2007) reported the promising potential of sugar beet pulp as great pectin source owing to its high pectin content (25–30% dry weight basis) and its availability in large quantities (van der Poel et al., 1998). Pectic substances are the natural polysaccharides present in the cell wall structure. They are composed by galactur- onic acid, rhamnose, arabinose and galactose (Drusch, 2007; Gromer et al., 2009). Pectin is usually extracted from apple pomace and citrus peels (Kurita et al., 2008; Min et al., 2011; Pourbafrani et al., 2010). It Abbreviations: DM, dry matter; FTIR, fourier transform infra-red; GC–MS, gas chromatography–mass spectrometry; HVED, high-voltage electrical discharges; SBP, sugar beet pulp. ∗ Corresponding author. Fax: +33 3 44 23 19 80. E-mail addresses: fouad.almohammed@utc.fr (F. Almohammed), eugene.vorobiev@utc.fr (E. Vorobiev). is used in many food applications as gelling agent for jams and jel- lies, as thickener, and as emulsifier in dairy products. It is also used in medical industry to reduce heart disease and in cosmetic products due to its gelling properties (Pagan et al., 2001). Traditionally, pectin is extracted from raw materials by hot acidified water (at temperatures 70–90 ◦ C and pH 1–3) during 1–6 h (Iglesias and Lozano, 2004; Kalapathy and Proctor, 2001). Pectin can also be extracted using galacturonase enzymes (Bonnin et al., 2002; Donaghy and McKay, 1994). Different alternative treatments like extrusion (Ralet et al., 1994; Shin et al., 2005), microwaves (Fishman et al., 2000; Kratchanova et al., 2004), ultrasound (Bagherian et al., 2011; Minjares-Fuentes et al., 2016), instant controlled pressure drop (Rezzoug et al., 2007), and subcritical water (Tanaka et al., 2012) can increase importantly the extraction yield of pectin from treated tissue. In the last decade, electrohydraulic high-voltage electrical discharges (HVED) were proposed as a non-thermal and low- energy consuming treatment for the recovery of valuable compounds from different biomass feedstocks, like grape by-products (Boussetta et al., 2012, 2011, 2009; Brianceau et al., 2016; Liu et al., 2011; Rajha http://dx.doi.org/10.1016/j.fbp.2017.03.005 0960-3085/© 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.