1. 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, Porto, Portugal
2CEB - Centre of Biological Engineering, University of Minho, Braga, Portugal
*corresponding author:
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 D 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 ± 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 , “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 FEDER ) and BioTecNorte operation (NORTE FEDER ) funded by European Regional Development Fund under the scope of Norte 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.
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