title: Biorefinery cascade processing for creating added value on tomato industrial by-products from Tunisia.
abstract: BACKGROUND
  In today's consumer perception of industrial processes and food production, aspects like food quality, human health, environmental safety, and energy security have become the keywords. Therefore, much effort has been extended toward adding value to biowastes of agri-food industries through biorefinery processing approaches. This study focused, for the first time, on the valorization of tomato by-products of a Tunisian industry for the recovery of value-added compounds using biorefinery cascade processing.
  
  
  RESULTS
  The process integrated supercritical CO2extraction of carotenoids within the oil fractions from tomato seeds (TS) and tomato peels (TP), followed by a batch isolation of protein from the residues. The remaining lignocellulosic matter from both fractions was then submitted to a liquid hot water (LHW) hydrolysis. Supercritical CO2experiments extracted 5.79% oleoresin, 410.53 mg lycopene/kg, and 31.38 mg β-carotene/kg from TP and 26.29% oil, 27.84 mg lycopene/kg, and 5.25 mg β-carotene/kg from TS, on dry weights. Protein extraction yields, nearing 30% of the initial protein contents equal to 13.28% in TP and 39.26% in TS, revealed that TP and TS are a rich source of essential amino acids. LHW treatment run at 120-200 °C, 50 bar for 30 min showed that a temperature of 160 °C was the most convenient for cellulose and hemicellulose hydrolysis from TP and TS, while keeping the degradation products low.
  
  
  CONCLUSIONS
  Results indicated that tomato by-products are not only a green source of lycopene-rich oleoresin and tomato seed oil (TSO) and of protein with good nutritional quality but also a source of lignocellulosic matter with potential for bioethanol production. This study would provide an important reference for the concept and the feasibility of the cascade fractionation of valuable compounds from tomato industrial by-products.Graphical abstractSchema of biorefinery cascade processing of tomato industrial by-products toward isolation of valuable fractions.
authors.affiliation: Laboratory of Environmental Bioprocesses, Centre of Biotechnology of Sfax, University of Sfax, PO Box 1177, 3018 Sfax, Tunisia.
authors.forename: Mouna
authors.initials: M
authors.lastname: Kehili
authors.affiliation: Institute of Environmental Technology and Energy Economics, Hamburg University of Technology, Eißendorfer Straße 40, 21073 Hamburg, Germany.
authors.forename: Lisa Marie
authors.initials: LM
authors.lastname: Schmidt
authors.affiliation: Institute of Thermal Separation Processes, Hamburg University of Technology, Eißendorfer Straße 38, 21073 Hamburg, Germany.
authors.forename: Wienke
authors.initials: W
authors.lastname: Reynolds
authors.affiliation: Ayachi Group Industry, El Mansoura, 6131 Siliana, Tunisia.
authors.forename: Ayachi
authors.initials: A
authors.lastname: Zammel
authors.affiliation: Institute of Thermal Separation Processes, Hamburg University of Technology, Eißendorfer Straße 38, 21073 Hamburg, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Zetzl
authors.affiliation: Institute of Thermal Separation Processes, Hamburg University of Technology, Eißendorfer Straße 38, 21073 Hamburg, Germany.
authors.forename: Irina
authors.initials: I
authors.lastname: Smirnova
authors.affiliation: Laboratory of Chemistry of Natural Substances UR11-ES74, Faculty of Sciences of Sfax, University of Sfax, PO Box 1171, 3000 Sfax, Tunisia.
authors.forename: Noureddine
authors.initials: N
authors.lastname: Allouche
authors.affiliation: Laboratory of Environmental Bioprocesses, Centre of Biotechnology of Sfax, University of Sfax, PO Box 1177, 3018 Sfax, Tunisia.
authors.forename: Sami
authors.initials: S
authors.lastname: Sayadi
keywords: Biorefinery; Carotenoids; Lignocellulose; Liquid hot water hydrolysis; Oil; Protein isolation; SC-CO2 extraction; Tomato industrial by-products