Introduction. Industrial transformation of tomatoes typically include a thermophysical peeling phase of the fruits, which lead to the production of large amount of wastes, namely peels. These wastes are currently used as feed for animal or sent to landfill leading to environmental and economical problems for the industry. However, they represent a cheap and rich source of several carotenoids, particularly lycopene. Therefore, in order to pursue the concept of ―zero waste‖ or ―total use‖ of agri-food residues with increasing industrial profitability, the recovery of these high-added value compounds is a challenge. Traditionally, these compounds are recovered by extraction with solvent which is a time consuming process and requires large quantities of solvents. The aim of this work, which was carried out in the frame of the European project ―FieldFood‖, was to assess the potential of pulsed electric field (PEF) technology alone or in combination with steam blanching, to improve the recovery of carotenoids from tomato peels. Materials and Methods. PEF treatments of whole tomato fruit were carried out at field strengths in the range 0.25-0.75 kV/cm and energy input between 0.25 and 5 kJ/kg. The evaluation of the cell disintegration index via impedance analysis was used to select optimal PEF treatment conditions. Tomato samples treated under these optimal conditions were then peeled with or without the application of a thermal treatment by steam (50–60–70°C). The achieved peels were subjected to solvent extraction in acetone for 24h, and the extracts were analysed by both spectrophotometric and HPLC analysis in order to evaluate the total carotenoids content and antioxidant activity of the extracts as well as the chemical composition of the extracts. Results. Results showed that, for each field strength applied, the cell disintegration index increased with increasing the energy input, reaching a saturation value for an energy input of 1 kJ/kg. The application of PEF pretreatment at different field strengths and at 1 kJ/kg at room temperature, allowed to increase the total carotenoids content and antioxidant activity of the extracts up to, respectively, 2.7 and 4.2-fold those detected in the untreated samples. The application of a combined treatment (PEF + steam blanching) significantly increased the carotenoids content and the antioxidant power of the extracts, allowing to save energy with respect to a conventional steam blanching treatment. HPLC analyses revealed that PEF pre-treatment alone or in combination with steam blanching increased lycopene concentration in the extracts with respect to the untreated samples. Moreover, no evidence of selective release or degradation of individual carotenoids due to PEF application was detected. Conclusions. Results obtained from this study demonstrate the potential of PEF as pre-treatment method to improve the efficiency of industrial processing of tomato fruits.

Effect of PEF and steam blanching treatments on the extraction yield of carotenoids from tomato wastes

Pataro, G.;Carullo D.;Capitoli M. M.;Ferrari, G.
2017-01-01

Abstract

Introduction. Industrial transformation of tomatoes typically include a thermophysical peeling phase of the fruits, which lead to the production of large amount of wastes, namely peels. These wastes are currently used as feed for animal or sent to landfill leading to environmental and economical problems for the industry. However, they represent a cheap and rich source of several carotenoids, particularly lycopene. Therefore, in order to pursue the concept of ―zero waste‖ or ―total use‖ of agri-food residues with increasing industrial profitability, the recovery of these high-added value compounds is a challenge. Traditionally, these compounds are recovered by extraction with solvent which is a time consuming process and requires large quantities of solvents. The aim of this work, which was carried out in the frame of the European project ―FieldFood‖, was to assess the potential of pulsed electric field (PEF) technology alone or in combination with steam blanching, to improve the recovery of carotenoids from tomato peels. Materials and Methods. PEF treatments of whole tomato fruit were carried out at field strengths in the range 0.25-0.75 kV/cm and energy input between 0.25 and 5 kJ/kg. The evaluation of the cell disintegration index via impedance analysis was used to select optimal PEF treatment conditions. Tomato samples treated under these optimal conditions were then peeled with or without the application of a thermal treatment by steam (50–60–70°C). The achieved peels were subjected to solvent extraction in acetone for 24h, and the extracts were analysed by both spectrophotometric and HPLC analysis in order to evaluate the total carotenoids content and antioxidant activity of the extracts as well as the chemical composition of the extracts. Results. Results showed that, for each field strength applied, the cell disintegration index increased with increasing the energy input, reaching a saturation value for an energy input of 1 kJ/kg. The application of PEF pretreatment at different field strengths and at 1 kJ/kg at room temperature, allowed to increase the total carotenoids content and antioxidant activity of the extracts up to, respectively, 2.7 and 4.2-fold those detected in the untreated samples. The application of a combined treatment (PEF + steam blanching) significantly increased the carotenoids content and the antioxidant power of the extracts, allowing to save energy with respect to a conventional steam blanching treatment. HPLC analyses revealed that PEF pre-treatment alone or in combination with steam blanching increased lycopene concentration in the extracts with respect to the untreated samples. Moreover, no evidence of selective release or degradation of individual carotenoids due to PEF application was detected. Conclusions. Results obtained from this study demonstrate the potential of PEF as pre-treatment method to improve the efficiency of industrial processing of tomato fruits.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11386/4716412
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