VALORIZATION OF TOMATO WASTES: INFLUENCE OF OHMIC HEATING PROCESS ON POLYPHENOLS EXTRACTION COELHO, Marta1,2; PEREIRA, Ricardo2; TEIXEIRA, JA2; PINTADO, Manuela1 1 Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina – Laboratório Associado, Escola Superior de Biotecnologia, Rua Arquiteto Lobão Vital, Apartado 2511, 4202-401 Porto, Portugal 2CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal *corresponding author: mpintado@porto.ucp.pt Introduction Tomato based products is one of the worldwide major agroindustrial sectors generating substantial amounts of wastes, with high economic and environmental costs[1]. These agroindustrial by-products e.g. skins and pulp remnants, are rich in bioactive compounds such as polyphenols [2–4]. Current extraction treatments, besides representing environmental hazards, may cause these by-products bioactive compounds degradation, promote toxicity, and reduce biological properties and health benefits, thus hampering their added value. Therefore, there is a growing interest in alternative extraction technologies, such as the case of Ohmic Heating (OH), an environmentally-friendly technique (i.e. use of electrical energy) [5]. This study aimed to optimize the extraction of phenolic compounds, antioxidants and carotenoids of tomato wastes through ohmic heating, as an alternative extraction technology. Materials and Methods Phenolic compounds analysis Antioxidant activity (ABTS+) Total phenolics (Folin-Ciocalteu) HPLC-DAD analysis Tomato by-products Central composite design for different extraction times, temperatures and ethanol concentrations Data fitted with 2nd order polynomial surface Results Fig. 1 – 3D Surface Plot of antioxidant activity of tomato by-products at different infusion temperatures and times. Fig. 2 – 3D Surface Plot of total phenolic compounds content of tomato by-products at different infusion temperatures and times. b a c Fig. 5- Individual polyphenols analysed by HPLC, of samples treated with different electric fields : a) Neochlorogenic acid; b) Rutin and c) Kaempferol – Black: 4 V cm-1; Blue: 6 V cm-1; Babyblue: 11 V cm-1 Fig. 3 - 3D Surface Plot of carotenoids of tomato by-products at different infusion temperatures and times. Fig. 4- Profiles to predict values and desirability The application of 6 V cm-1 with longer times, higher temperatures and higher ethanol percentage resulted in extracts with higher total phenolic compounds content (2.550 ± 0.070 mg gallic acid equivalent/g biomass). Phenolic acids such as rutin, kaempferol and neochlorogenic acid were individually identified and quantified. Conclusions Conclusions The highest phenolic compounds content and the highest level of antioxidant activity was achieved when tomato wastes were heated for 15 min at 70 °C with 70% of ethanol. OH shows to have a high potential as an environmentally-friendly, economic and fast process for the recovery of polyphenols from industrial tomato by-products. Acknowledgements References The authors would like to thank to the project Co-promoção nº 016403, “MULTIBIOREFINERY”, supported by Programa Operacional Competitividade e Internacionalização e pelo Programa Operacional Regional de Lisboa, na sua componente FEDER, e pela Fundação para a Ciência e Tecnologia and project UID/Multi/50016/2013 , administrated by FCT. Furthermore, This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte”The author Marta Coelho would like to acknowledge FCT for your PhD grant with the reference [grant number SFRH/BD/111884/2015] and Ricardo Pereira SFRH/BPD/81887/2011. 1. V. Bergougnoux, Biotechnology Advances 32, 170 (2014). 2. G. Tommonaro, A. Poli, S. De Rosa, and B. Nicolaus, Molecules 13, 1384 (2008). 3. V. Lavelli and M. C. Torresani, Food Chemistry 125, 529 (2011). 4. M. Del Valle, M. Cámara, and M. E. Torija, Journal of the Science of Food and Agriculture 86, 1232 (2006). 5. R. N. Pereira and A. A. Vicente, Food Research International 43, 1936 (2010).