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Cristina L. M. Silva - One of the best experts on this subject based on the ideXlab platform.
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biochemical and colour changes of watercress Nasturtium Officinale r br during freezing and frozen storage
Journal of Food Engineering, 2009Co-Authors: Elsa M Goncalves, Rui M.s. Cruz, Marta Abreu, Teresa R S Brandao, Cristina L. M. SilvaAbstract:Abstract The effects of water blanching, freezing, and frozen storage during 400 days at three different temperatures (−7, −15 and −30 °C), on watercress (Nasturtium Officinale R. Br.) colour Hunter Lab parameters, chlorophyll degradation, vitamin C content loss and peroxidase (POD) activity were evaluated. The blanching induced significant changes on colour values and chlorophylls and vitamin C contents. POD activity was reduced 85% from its initial value. Freezing did not affect chlorophylls and vitamin C levels, however, promoted significant differences in colour values and POD residual activity. During frozen storage, ascorbic acid (AA) and POD activity degradations followed first-order kinetics, and colour parameters (LH · aH · bH, −aH/bH, LH · aH/bH, LH/aH · bH and hue ( h H 0 )) were successfully described by zero-order kinetics. The storage temperature effect was successfully described by the Arrhenius law. Chlorophylls and dehydroascorbic acid (DHAA) contents were kept constant during frozen storage.
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Effect of cold chain temperature abuses on the quality of frozen watercress (Nasturtium Officinale R. Br.)
Journal of Food Engineering, 2009Co-Authors: Rui M.s. Cruz, Margarida C. Vieira, Cristina L. M. SilvaAbstract:Abstract The objective of this work was to study the effect of temperature abuses on the colour and vitamin C content of a new frozen vegetable, watercress (Nasturtium Officinale R. Br.). The vitamin C content, expressed as ascorbic (AA) and dehydroascorbic (DHAA) acids, and colour, expressed in the Hunter Lab parameters, were evaluated along a plan of temperature abuses, based on a real situation for a four month frozen storage period. A comparison between the hue angle and AA experimental data and prediction models, using kinetic parameters determined under isothermal conditions, was also run. The colour showed some variation, namely on the parameters L, a, TCD (Total Colour Difference) and hue angle. Although, during the temperature abuses, some fluctuation was observed, no vitamin C degradation or major colour changes occurred. A zero-order and a first-order prediction models fitted well the experimental data for the hue angle and AA behaviour with temperature abuses, respectively. In general, the frozen watercress colour and vitamin C content were not impaired by the imposed temperature abuses. This work will help to predict and understand the sensory and nutritional quality changes of frozen watercress that might occur during frozen storage and distribution in the cold chain under the used conditions.
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Effect of heat and thermosonication treatments on watercress (Nasturtium Officinale) vitamin C degradation kinetics
Innovative Food Science & Emerging Technologies, 2008Co-Authors: Rui M.s. Cruz, Margarida C. Vieira, Cristina L. M. SilvaAbstract:Abstract The use of ultrasound in food processing creates novel and interesting methodologies, which are often complementary to classical techniques. In this work, the effect of heat and the combined treatment heat/ultrasound (thermosonication) on the thermal degradation kinetics of vitamin C in watercress ( Nasturtium Officinale ) was studied in the temperature range of 82.5 to 92.5 °C. First order reaction kinetics adequately described the vitamin C losses during both blanching processes. The activation energies and the reaction rates at 87.5 °C for heat (H) and thermosonication (Ts) treatments were, respectively, E a vitC H = 150.47 ± 42.81 kJ mol − 1 and E a vitC Ts = 136.20 ± 60.97 kJ mol − 1 , and k 87.5 °CvitC H = 0.75 ± 0.10 min − 1 and k 87.5 °CvitC Ts = 0.58 ± 0.11 min − 1 . No significant differences ( P > 0.05 ) were detected between both treatments. The thermosonication treatment was found to be a better blanching process, since it inactivates watercress peroxidase at less severe blanching conditions and consequently retains vitamin C content at higher levels. The present findings will help to optimise the blanching conditions for the production of a new and healthy frozen product, watercress, with heat and a new blanching process methodology. Industrial relevance Thermosonication blanching can be useful since it reduces processing times, and consequently minimizes the adverse effects of heating on watercress quality. This new application will provide good material, in terms of vitamin C, for further processes, and can be an excellent alternative to the traditional heat treatment.
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Modelling kinetics of watercress (Nasturtium Officinale) colour changes due to heat and thermosonication treatments
Innovative Food Science & Emerging Technologies, 2007Co-Authors: Rui M.s. Cruz, Margarida C. Vieira, Cristina L. M. SilvaAbstract:Abstract Watercress ( Nasturtium Officinale ) colour changes due to blanching by heat and a combined treatment of heat/ultrasound (thermosonication) were studied in the temperature range of 82.5 to 92.5 °C. The application of thermosonication was intended to enable less severe blanching treatments and, therefore, improve the quality of the blanched product. The thermosonication blanching processes promoted changes of the green colour ( a n parameter) at a higher rate ( P P > 0.05) were detected between heat and thermosonication blanching processes in terms of the colour parameters L n , b n and TCD changes. In both treatments, a fractional first order model fitted well the experimental data for L n , a n and b n ( R H 2 = 0.99; R Ts 2 = 0.99) and TCD ( R H 2 = 0.92; R Ts 2 = 0.96) colour parameters. The chlorophylls content showed no significant differences ( P > 0.05) between thermally treated and thermosonicated watercress samples. The present findings will help to evaluate the effectiveness of thermosonication as a novel process to replace the classical heat treatment. Industrial relevance Conventional blanching commonly results in severe losses or destruction of nutrients due to process intensity and extended process times. Consequently, the attempts to use the synergistic effects of heat and ultrasound (at least) for enzyme inactivation are of high relevance. The results, although not conclusive, indicate, that they may aid optimization of blanching processes.
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Effect of heat and thermosonication treatments on peroxidase inactivation kinetics in watercress (Nasturtium Officinale)
Journal of Food Engineering, 2006Co-Authors: Rui M.s. Cruz, Margarida C. Vieira, Cristina L. M. SilvaAbstract:Abstract The effect of heat and the combined heat/ultrasound (thermosonication) treatment on the inactivation kinetics of peroxidase in watercress (Nasturtium Officinale) was studied in the temperature range of 40–92.5 °C. In the heat blanching processes, the enzyme kinetics showed a first-order biphasic inactivation model. The activation energies and the rates of the reaction at a reference temperature for both the heat-labile and heat-resistant fractions were, respectively, Ea1 = 421 ± 115 kJ mol−1 and Ea2 = 352 ± 81 kJ mol−1, k 1 84 . 6 ° C = 18 ± 14 min - 1 and k 2 84 . 6 ° C = 0 . 24 ± 0 . 14 min - 1 . The initial relative specific activity for both isoenzyme fractions were also estimated, being C01 = 0.5 ± 0.08 μmol min−1 mg protein−1 and C02 = 0.5 ± 0.06 μmol min−1 mg protein−1, respectively. The application of thermosonication was studied to enable less severe thermal treatments and, therefore, improving the quality of the blanched product. In this treatment the enzyme kinetics showed a first-order model. The activation energy, the rate of reaction at a reference temperature and the initial relative specific activity were, respectively, Ea3 = 496 ± 65 kJ mol−1, k 3 87 . 5 ° C = 10 ± 2 min - 1 and C03 = 1 ± 0.05 μmol min−1 mg protein−1, proving that the enzyme became more heat labile. The present findings will help to design the blanching conditions for the production of a new and healthy frozen product, watercress (Nasturtium Officinale), with minimized colour or flavour changes along its shelf life.
Marta A. Carballo - One of the best experts on this subject based on the ideXlab platform.
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in vivo antigenotoxic activity of watercress juice Nasturtium Officinale against induced dna damage
Journal of Applied Toxicology, 2013Co-Authors: Natalia A. Casanova, Julia Irene Ariagno, Gabriela Ruth Mendeluk, Elisa M. Petenatti, Luis Alberto Palaoro, Marcela Lopez M Nigro, Maria De Los A Gette, Marta A. CarballoAbstract:The present study was carried out to investigate the genotoxicity as well as possible protective activity against damage induced by cyclophosphamide (CP) of the aqueous juice of watercress (Nasturtium Officinale, W.T. Aiton) in vivo. Male and female Swiss mice 7–8 weeks old (N = 48) were treated by gavage with 1 g kg−1 body weight and 0.5 g kg−1 body weight of watercress juice during 15 consecutive days. Genotoxicity and its possible protective effect were tested by the comet assay in peripheral blood cells and the micronucleus test in bone marrow. In addition, biopsies of the bladder, epididymis and testicles of mice were performed to extend the experimental design. Watercress juice per se did not induce genetic damage according to the comet assay and micronucleus study, exhibiting a protective activity against CP (P < 0.05 and P < 0.001, respectively). The comparative analysis of bladder histological changes obtained in the watercress plus CP group against those treated with CP alone suggests a probable protective effect. Further studies are needed in order to establish the protective role of watercress juice against DNA damage. Copyright © 2012 John Wiley & Sons, Ltd.
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In vivo antigenotoxic activity of watercress juice (Nasturtium Officinale) against induced DNA damage.
Journal of applied toxicology : JAT, 2012Co-Authors: Natalia A. Casanova, Julia Irene Ariagno, Marcela M. López Nigro, Gabriela Ruth Mendeluk, María A. Gette, Elisa M. Petenatti, Luis Alberto Palaoro, Marta A. CarballoAbstract:The present study was carried out to investigate the genotoxicity as well as possible protective activity against damage induced by cyclophosphamide (CP) of the aqueous juice of watercress (Nasturtium Officinale, W.T. Aiton) in vivo. Male and female Swiss mice 7–8 weeks old (N = 48) were treated by gavage with 1 g kg−1 body weight and 0.5 g kg−1 body weight of watercress juice during 15 consecutive days. Genotoxicity and its possible protective effect were tested by the comet assay in peripheral blood cells and the micronucleus test in bone marrow. In addition, biopsies of the bladder, epididymis and testicles of mice were performed to extend the experimental design. Watercress juice per se did not induce genetic damage according to the comet assay and micronucleus study, exhibiting a protective activity against CP (P
Rui M.s. Cruz - One of the best experts on this subject based on the ideXlab platform.
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biochemical and colour changes of watercress Nasturtium Officinale r br during freezing and frozen storage
Journal of Food Engineering, 2009Co-Authors: Elsa M Goncalves, Rui M.s. Cruz, Marta Abreu, Teresa R S Brandao, Cristina L. M. SilvaAbstract:Abstract The effects of water blanching, freezing, and frozen storage during 400 days at three different temperatures (−7, −15 and −30 °C), on watercress (Nasturtium Officinale R. Br.) colour Hunter Lab parameters, chlorophyll degradation, vitamin C content loss and peroxidase (POD) activity were evaluated. The blanching induced significant changes on colour values and chlorophylls and vitamin C contents. POD activity was reduced 85% from its initial value. Freezing did not affect chlorophylls and vitamin C levels, however, promoted significant differences in colour values and POD residual activity. During frozen storage, ascorbic acid (AA) and POD activity degradations followed first-order kinetics, and colour parameters (LH · aH · bH, −aH/bH, LH · aH/bH, LH/aH · bH and hue ( h H 0 )) were successfully described by zero-order kinetics. The storage temperature effect was successfully described by the Arrhenius law. Chlorophylls and dehydroascorbic acid (DHAA) contents were kept constant during frozen storage.
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Effect of cold chain temperature abuses on the quality of frozen watercress (Nasturtium Officinale R. Br.)
Journal of Food Engineering, 2009Co-Authors: Rui M.s. Cruz, Margarida C. Vieira, Cristina L. M. SilvaAbstract:Abstract The objective of this work was to study the effect of temperature abuses on the colour and vitamin C content of a new frozen vegetable, watercress (Nasturtium Officinale R. Br.). The vitamin C content, expressed as ascorbic (AA) and dehydroascorbic (DHAA) acids, and colour, expressed in the Hunter Lab parameters, were evaluated along a plan of temperature abuses, based on a real situation for a four month frozen storage period. A comparison between the hue angle and AA experimental data and prediction models, using kinetic parameters determined under isothermal conditions, was also run. The colour showed some variation, namely on the parameters L, a, TCD (Total Colour Difference) and hue angle. Although, during the temperature abuses, some fluctuation was observed, no vitamin C degradation or major colour changes occurred. A zero-order and a first-order prediction models fitted well the experimental data for the hue angle and AA behaviour with temperature abuses, respectively. In general, the frozen watercress colour and vitamin C content were not impaired by the imposed temperature abuses. This work will help to predict and understand the sensory and nutritional quality changes of frozen watercress that might occur during frozen storage and distribution in the cold chain under the used conditions.
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Effect of heat and thermosonication treatments on watercress (Nasturtium Officinale) vitamin C degradation kinetics
Innovative Food Science & Emerging Technologies, 2008Co-Authors: Rui M.s. Cruz, Margarida C. Vieira, Cristina L. M. SilvaAbstract:Abstract The use of ultrasound in food processing creates novel and interesting methodologies, which are often complementary to classical techniques. In this work, the effect of heat and the combined treatment heat/ultrasound (thermosonication) on the thermal degradation kinetics of vitamin C in watercress ( Nasturtium Officinale ) was studied in the temperature range of 82.5 to 92.5 °C. First order reaction kinetics adequately described the vitamin C losses during both blanching processes. The activation energies and the reaction rates at 87.5 °C for heat (H) and thermosonication (Ts) treatments were, respectively, E a vitC H = 150.47 ± 42.81 kJ mol − 1 and E a vitC Ts = 136.20 ± 60.97 kJ mol − 1 , and k 87.5 °CvitC H = 0.75 ± 0.10 min − 1 and k 87.5 °CvitC Ts = 0.58 ± 0.11 min − 1 . No significant differences ( P > 0.05 ) were detected between both treatments. The thermosonication treatment was found to be a better blanching process, since it inactivates watercress peroxidase at less severe blanching conditions and consequently retains vitamin C content at higher levels. The present findings will help to optimise the blanching conditions for the production of a new and healthy frozen product, watercress, with heat and a new blanching process methodology. Industrial relevance Thermosonication blanching can be useful since it reduces processing times, and consequently minimizes the adverse effects of heating on watercress quality. This new application will provide good material, in terms of vitamin C, for further processes, and can be an excellent alternative to the traditional heat treatment.
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Modelling kinetics of watercress (Nasturtium Officinale) colour changes due to heat and thermosonication treatments
Innovative Food Science & Emerging Technologies, 2007Co-Authors: Rui M.s. Cruz, Margarida C. Vieira, Cristina L. M. SilvaAbstract:Abstract Watercress ( Nasturtium Officinale ) colour changes due to blanching by heat and a combined treatment of heat/ultrasound (thermosonication) were studied in the temperature range of 82.5 to 92.5 °C. The application of thermosonication was intended to enable less severe blanching treatments and, therefore, improve the quality of the blanched product. The thermosonication blanching processes promoted changes of the green colour ( a n parameter) at a higher rate ( P P > 0.05) were detected between heat and thermosonication blanching processes in terms of the colour parameters L n , b n and TCD changes. In both treatments, a fractional first order model fitted well the experimental data for L n , a n and b n ( R H 2 = 0.99; R Ts 2 = 0.99) and TCD ( R H 2 = 0.92; R Ts 2 = 0.96) colour parameters. The chlorophylls content showed no significant differences ( P > 0.05) between thermally treated and thermosonicated watercress samples. The present findings will help to evaluate the effectiveness of thermosonication as a novel process to replace the classical heat treatment. Industrial relevance Conventional blanching commonly results in severe losses or destruction of nutrients due to process intensity and extended process times. Consequently, the attempts to use the synergistic effects of heat and ultrasound (at least) for enzyme inactivation are of high relevance. The results, although not conclusive, indicate, that they may aid optimization of blanching processes.
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Effect of heat and thermosonication treatments on peroxidase inactivation kinetics in watercress (Nasturtium Officinale)
Journal of Food Engineering, 2006Co-Authors: Rui M.s. Cruz, Margarida C. Vieira, Cristina L. M. SilvaAbstract:Abstract The effect of heat and the combined heat/ultrasound (thermosonication) treatment on the inactivation kinetics of peroxidase in watercress (Nasturtium Officinale) was studied in the temperature range of 40–92.5 °C. In the heat blanching processes, the enzyme kinetics showed a first-order biphasic inactivation model. The activation energies and the rates of the reaction at a reference temperature for both the heat-labile and heat-resistant fractions were, respectively, Ea1 = 421 ± 115 kJ mol−1 and Ea2 = 352 ± 81 kJ mol−1, k 1 84 . 6 ° C = 18 ± 14 min - 1 and k 2 84 . 6 ° C = 0 . 24 ± 0 . 14 min - 1 . The initial relative specific activity for both isoenzyme fractions were also estimated, being C01 = 0.5 ± 0.08 μmol min−1 mg protein−1 and C02 = 0.5 ± 0.06 μmol min−1 mg protein−1, respectively. The application of thermosonication was studied to enable less severe thermal treatments and, therefore, improving the quality of the blanched product. In this treatment the enzyme kinetics showed a first-order model. The activation energy, the rate of reaction at a reference temperature and the initial relative specific activity were, respectively, Ea3 = 496 ± 65 kJ mol−1, k 3 87 . 5 ° C = 10 ± 2 min - 1 and C03 = 1 ± 0.05 μmol min−1 mg protein−1, proving that the enzyme became more heat labile. The present findings will help to design the blanching conditions for the production of a new and healthy frozen product, watercress (Nasturtium Officinale), with minimized colour or flavour changes along its shelf life.
Natalia A. Casanova - One of the best experts on this subject based on the ideXlab platform.
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in vivo antigenotoxic activity of watercress juice Nasturtium Officinale against induced dna damage
Journal of Applied Toxicology, 2013Co-Authors: Natalia A. Casanova, Julia Irene Ariagno, Gabriela Ruth Mendeluk, Elisa M. Petenatti, Luis Alberto Palaoro, Marcela Lopez M Nigro, Maria De Los A Gette, Marta A. CarballoAbstract:The present study was carried out to investigate the genotoxicity as well as possible protective activity against damage induced by cyclophosphamide (CP) of the aqueous juice of watercress (Nasturtium Officinale, W.T. Aiton) in vivo. Male and female Swiss mice 7–8 weeks old (N = 48) were treated by gavage with 1 g kg−1 body weight and 0.5 g kg−1 body weight of watercress juice during 15 consecutive days. Genotoxicity and its possible protective effect were tested by the comet assay in peripheral blood cells and the micronucleus test in bone marrow. In addition, biopsies of the bladder, epididymis and testicles of mice were performed to extend the experimental design. Watercress juice per se did not induce genetic damage according to the comet assay and micronucleus study, exhibiting a protective activity against CP (P < 0.05 and P < 0.001, respectively). The comparative analysis of bladder histological changes obtained in the watercress plus CP group against those treated with CP alone suggests a probable protective effect. Further studies are needed in order to establish the protective role of watercress juice against DNA damage. Copyright © 2012 John Wiley & Sons, Ltd.
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In vivo antigenotoxic activity of watercress juice (Nasturtium Officinale) against induced DNA damage.
Journal of applied toxicology : JAT, 2012Co-Authors: Natalia A. Casanova, Julia Irene Ariagno, Marcela M. López Nigro, Gabriela Ruth Mendeluk, María A. Gette, Elisa M. Petenatti, Luis Alberto Palaoro, Marta A. CarballoAbstract:The present study was carried out to investigate the genotoxicity as well as possible protective activity against damage induced by cyclophosphamide (CP) of the aqueous juice of watercress (Nasturtium Officinale, W.T. Aiton) in vivo. Male and female Swiss mice 7–8 weeks old (N = 48) were treated by gavage with 1 g kg−1 body weight and 0.5 g kg−1 body weight of watercress juice during 15 consecutive days. Genotoxicity and its possible protective effect were tested by the comet assay in peripheral blood cells and the micronucleus test in bone marrow. In addition, biopsies of the bladder, epididymis and testicles of mice were performed to extend the experimental design. Watercress juice per se did not induce genetic damage according to the comet assay and micronucleus study, exhibiting a protective activity against CP (P
Margarida C. Vieira - One of the best experts on this subject based on the ideXlab platform.
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Effect of cold chain temperature abuses on the quality of frozen watercress (Nasturtium Officinale R. Br.)
Journal of Food Engineering, 2009Co-Authors: Rui M.s. Cruz, Margarida C. Vieira, Cristina L. M. SilvaAbstract:Abstract The objective of this work was to study the effect of temperature abuses on the colour and vitamin C content of a new frozen vegetable, watercress (Nasturtium Officinale R. Br.). The vitamin C content, expressed as ascorbic (AA) and dehydroascorbic (DHAA) acids, and colour, expressed in the Hunter Lab parameters, were evaluated along a plan of temperature abuses, based on a real situation for a four month frozen storage period. A comparison between the hue angle and AA experimental data and prediction models, using kinetic parameters determined under isothermal conditions, was also run. The colour showed some variation, namely on the parameters L, a, TCD (Total Colour Difference) and hue angle. Although, during the temperature abuses, some fluctuation was observed, no vitamin C degradation or major colour changes occurred. A zero-order and a first-order prediction models fitted well the experimental data for the hue angle and AA behaviour with temperature abuses, respectively. In general, the frozen watercress colour and vitamin C content were not impaired by the imposed temperature abuses. This work will help to predict and understand the sensory and nutritional quality changes of frozen watercress that might occur during frozen storage and distribution in the cold chain under the used conditions.
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Effect of heat and thermosonication treatments on watercress (Nasturtium Officinale) vitamin C degradation kinetics
Innovative Food Science & Emerging Technologies, 2008Co-Authors: Rui M.s. Cruz, Margarida C. Vieira, Cristina L. M. SilvaAbstract:Abstract The use of ultrasound in food processing creates novel and interesting methodologies, which are often complementary to classical techniques. In this work, the effect of heat and the combined treatment heat/ultrasound (thermosonication) on the thermal degradation kinetics of vitamin C in watercress ( Nasturtium Officinale ) was studied in the temperature range of 82.5 to 92.5 °C. First order reaction kinetics adequately described the vitamin C losses during both blanching processes. The activation energies and the reaction rates at 87.5 °C for heat (H) and thermosonication (Ts) treatments were, respectively, E a vitC H = 150.47 ± 42.81 kJ mol − 1 and E a vitC Ts = 136.20 ± 60.97 kJ mol − 1 , and k 87.5 °CvitC H = 0.75 ± 0.10 min − 1 and k 87.5 °CvitC Ts = 0.58 ± 0.11 min − 1 . No significant differences ( P > 0.05 ) were detected between both treatments. The thermosonication treatment was found to be a better blanching process, since it inactivates watercress peroxidase at less severe blanching conditions and consequently retains vitamin C content at higher levels. The present findings will help to optimise the blanching conditions for the production of a new and healthy frozen product, watercress, with heat and a new blanching process methodology. Industrial relevance Thermosonication blanching can be useful since it reduces processing times, and consequently minimizes the adverse effects of heating on watercress quality. This new application will provide good material, in terms of vitamin C, for further processes, and can be an excellent alternative to the traditional heat treatment.
-
Modelling kinetics of watercress (Nasturtium Officinale) colour changes due to heat and thermosonication treatments
Innovative Food Science & Emerging Technologies, 2007Co-Authors: Rui M.s. Cruz, Margarida C. Vieira, Cristina L. M. SilvaAbstract:Abstract Watercress ( Nasturtium Officinale ) colour changes due to blanching by heat and a combined treatment of heat/ultrasound (thermosonication) were studied in the temperature range of 82.5 to 92.5 °C. The application of thermosonication was intended to enable less severe blanching treatments and, therefore, improve the quality of the blanched product. The thermosonication blanching processes promoted changes of the green colour ( a n parameter) at a higher rate ( P P > 0.05) were detected between heat and thermosonication blanching processes in terms of the colour parameters L n , b n and TCD changes. In both treatments, a fractional first order model fitted well the experimental data for L n , a n and b n ( R H 2 = 0.99; R Ts 2 = 0.99) and TCD ( R H 2 = 0.92; R Ts 2 = 0.96) colour parameters. The chlorophylls content showed no significant differences ( P > 0.05) between thermally treated and thermosonicated watercress samples. The present findings will help to evaluate the effectiveness of thermosonication as a novel process to replace the classical heat treatment. Industrial relevance Conventional blanching commonly results in severe losses or destruction of nutrients due to process intensity and extended process times. Consequently, the attempts to use the synergistic effects of heat and ultrasound (at least) for enzyme inactivation are of high relevance. The results, although not conclusive, indicate, that they may aid optimization of blanching processes.
-
Effect of heat and thermosonication treatments on peroxidase inactivation kinetics in watercress (Nasturtium Officinale)
Journal of Food Engineering, 2006Co-Authors: Rui M.s. Cruz, Margarida C. Vieira, Cristina L. M. SilvaAbstract:Abstract The effect of heat and the combined heat/ultrasound (thermosonication) treatment on the inactivation kinetics of peroxidase in watercress (Nasturtium Officinale) was studied in the temperature range of 40–92.5 °C. In the heat blanching processes, the enzyme kinetics showed a first-order biphasic inactivation model. The activation energies and the rates of the reaction at a reference temperature for both the heat-labile and heat-resistant fractions were, respectively, Ea1 = 421 ± 115 kJ mol−1 and Ea2 = 352 ± 81 kJ mol−1, k 1 84 . 6 ° C = 18 ± 14 min - 1 and k 2 84 . 6 ° C = 0 . 24 ± 0 . 14 min - 1 . The initial relative specific activity for both isoenzyme fractions were also estimated, being C01 = 0.5 ± 0.08 μmol min−1 mg protein−1 and C02 = 0.5 ± 0.06 μmol min−1 mg protein−1, respectively. The application of thermosonication was studied to enable less severe thermal treatments and, therefore, improving the quality of the blanched product. In this treatment the enzyme kinetics showed a first-order model. The activation energy, the rate of reaction at a reference temperature and the initial relative specific activity were, respectively, Ea3 = 496 ± 65 kJ mol−1, k 3 87 . 5 ° C = 10 ± 2 min - 1 and C03 = 1 ± 0.05 μmol min−1 mg protein−1, proving that the enzyme became more heat labile. The present findings will help to design the blanching conditions for the production of a new and healthy frozen product, watercress (Nasturtium Officinale), with minimized colour or flavour changes along its shelf life.
