Antonio Mulet - Academia.edu (original) (raw)

Papers by Antonio Mulet

... Keywords : ultrasonics, physical properties, quality control ... Pnlabrrrs C117z,e: ultrasoni... more ... Keywords : ultrasonics, physical properties, quality control ... Pnlabrrrs C117z,e: ultrasonidos, propiedades fisicas, control de calidad ... If the ultrasonic signal finds discontinuities in its path, for example a hole inside a potato, part of the energy will be attenuated, thus reducing the ...

Journal of Food Engineering, 2015

ABSTRACT Atmospheric freeze drying consists of a convective drying process using air at a tempera... more ABSTRACT Atmospheric freeze drying consists of a convective drying process using air at a temperature below the freezing point of the processed product, and with a very low relative humidity content. This paper focuses on the use of a simple one-dimensional model considering moving boundary vapor diffusion to describe the ultrasonic assisted atmospheric freeze-drying of foodstuffs. The case study is the drying of apple cubes (8.8 mm) at different air velocities (1, 2, 4 and 6 m/s), temperatures (−5, −10 and −15 °C), without and with (25, 50 and 75 W) power ultrasound application. By fitting the proposed diffusion model to the experimental drying kinetics, the effective diffusivity of water vapor in the dried product was estimated. The model was successfully validated by drying apple samples of different size and geometry (cubes and cylinders). Finally, a 23 factorial design of experiments revealed that the most relevant operating parameter affecting the drying time was the applied ultrasound power level.

Defect and Diffusion Forum, 2008

Experiments on the extraction of sugar from carob pods have been carried out at 20, 30, 40 and 50... more Experiments on the extraction of sugar from carob pods have been carried out at 20, 30, 40 and 50 °C respectively, in order to study the temperature effect on the extraction rate. Particle size of the ground pods was between 0.5 and 1 cm. From experimental data and considering only the period where the mass transfer (sugars) occurs by diffusion, a characteristic kinetic equation for this period has been established.

The main aim of this work was to test a diffusion model to describe atmospheric freeze drying (AF... more The main aim of this work was to test a diffusion model to describe atmospheric freeze drying (AFD) and hot air drying (HAD) kinetics of different products. HAD (50 ºC and 2 ms-1) and AFD (-14 ºC, 2 ms-1) experiments were carried out for eggplant, apple and carrot cubes (side 10 mm). Kinetics were described using a diffusion model neglecting the external resistance to water transfer and the shrinkage of the samples. A good fit was obtained for AFD of apple and carrot, where assumptions considered in the model formulation were properly chosen.

The application of power ultrasound could constitute a way to improve traditional convective dryi... more The application of power ultrasound could constitute a way to improve traditional convective drying systems. There still exists a lack of knowledge on this technology in order to address industrial applications. The aim of this work was to identify the influence of the textural properties of different vegetable products on the ultrasonic assisted convective drying. For that purpose, experimental drying kinetics (40 ºC and 1 m/s) of different vegetable products (orange and lemon peel, carrot, potato and eggplant) were carried out applying different ultrasonic powers (0, 6, 12, 18, 25, 30 and 37 kW/m3). In every product, a similar diffusion model was used to identify an average effective diffusivity for the different ultrasonic powers. Product’s textural properties were assessed by Textural Profile Analysis (TPA). Linear relationships were established between the identified effective diffusivity and the applied ultrasonic power for the different products. The positive slopes of the li...

Dehydration constitutes a traditional preservation method for fruits and vegetables and it repres... more Dehydration constitutes a traditional preservation method for fruits and vegetables and it represents a very important operation in food processing. The way how water is removed from food affects the final product quality, thus the characteristics of dried products are dependent on the drying technique used. The main objective of the present study was to evaluate the effect of different drying techniques on the quality of dried eggplant. For this purpose, cubic samples (10 mm side) were obtained from the flesh of Spanish origin eggplants (Solanum melongena var. Black Enorma). Three different drying techniques were applied: hot air drying (HAD, 50 ºC and 2 m/s), atmospheric freeze drying (AFD, -14 ºC and 2 m/s) and vacuum freeze drying (VFD). The drying kinetics of HAD and AFD were determined by weighing the samples at preset times during the process. To evaluate the influence of drying method on the final quality of the product, rehydration kinetics of HAD, AFD and VFD samples were ...

Intermittent drying technology implements varying-time operating conditions to improve process en... more Intermittent drying technology implements varying-time operating conditions to improve process energy efficiency in comparison with other conventional convective drying techniques. One method of intermittent drying involves heating and resting periods. In heating periods, hot air removes the moisture and increases the material temperature by forced convection. In resting (or tempering) periods, the change of the temperature and moisture content takes place without heat supply by free convection. The mass transfer phenomena that take place during resting period may be modified by power ultrasound application. External resistance to mass transfer may be affected by pressure variations, oscillating velocities and microstreaming at the solid-gas interfaces. Internal resistance may be reduced by alternating expansion and compression cycles produced by ultrasound in the material and also through some effects on the interfaces of intercellular spaces, which may contribute to faster water d...

The final composition of cheese products constitutes one of their quality attributes and its know... more The final composition of cheese products constitutes one of their quality attributes and its knowledge in quality control is important. The measurement of ultrasonic velocity is a non-destructive technique, which allows the determination of foodstuff composition. Ultrasonic velocities in both cheese analogues and commercial cheese spreads were determined at different temperatures. The protein, fat and moisture contents of the samples ranged between 8.54 and 12.1 % (wb), 0.2 and 30.1 % (wb) and 57.5 and 81 % (wb), respectively. At 18ºC the ultrasonic velocity was not dependent on the cheese composition. The ultrasound velocity increased with the increase of fat content at temperatures lower than 18ºC and decreased for higher temperatures. From ultrasonic velocity measurements on cheese analogues, a model was developed to correlate the ultrasonic velocity, temperature and composition. This model allowed a good assessment of the composition of independent samples of cheese spreads.

Journal of Food Engineering, 2015

ABSTRACT The daily challenge involved in operating a process is the attainment of the objectives.... more ABSTRACT The daily challenge involved in operating a process is the attainment of the objectives. Process management requires the use of tools adapted to the system’s complexity. In order to obtain real time results, simplified mechanistic modelling offers a way to deal with this. To this end, carob pod (Ceratonia Siliqua, L.) kibbles extraction is addressed in this work. They are a source of different, valuable components and have a complex structure and a highly variable concentration of components. The components considered are sugars and soluble polyphenols. Obtaining the extracts with an optimal composition of a particular component, while avoiding or limiting other components in the extract, is a challenge to be addressed. Two steps can be considered: solubilization and diffusion, modelled by means of a first order reaction and by considering slab geometry. The optimal processing time and temperature are obtained by taking a particular kibble size and composition into account.

... Keywords : ultrasonics, physical properties, quality control ... Pnlabrrrs C117z,e: ultrasoni... more ... Keywords : ultrasonics, physical properties, quality control ... Pnlabrrrs C117z,e: ultrasonidos, propiedades fisicas, control de calidad ... If the ultrasonic signal finds discontinuities in its path, for example a hole inside a potato, part of the energy will be attenuated, thus reducing the ...

Journal of Food Engineering, 2015

ABSTRACT Atmospheric freeze drying consists of a convective drying process using air at a tempera... more ABSTRACT Atmospheric freeze drying consists of a convective drying process using air at a temperature below the freezing point of the processed product, and with a very low relative humidity content. This paper focuses on the use of a simple one-dimensional model considering moving boundary vapor diffusion to describe the ultrasonic assisted atmospheric freeze-drying of foodstuffs. The case study is the drying of apple cubes (8.8 mm) at different air velocities (1, 2, 4 and 6 m/s), temperatures (−5, −10 and −15 °C), without and with (25, 50 and 75 W) power ultrasound application. By fitting the proposed diffusion model to the experimental drying kinetics, the effective diffusivity of water vapor in the dried product was estimated. The model was successfully validated by drying apple samples of different size and geometry (cubes and cylinders). Finally, a 23 factorial design of experiments revealed that the most relevant operating parameter affecting the drying time was the applied ultrasound power level.

Defect and Diffusion Forum, 2008

Experiments on the extraction of sugar from carob pods have been carried out at 20, 30, 40 and 50... more Experiments on the extraction of sugar from carob pods have been carried out at 20, 30, 40 and 50 °C respectively, in order to study the temperature effect on the extraction rate. Particle size of the ground pods was between 0.5 and 1 cm. From experimental data and considering only the period where the mass transfer (sugars) occurs by diffusion, a characteristic kinetic equation for this period has been established.

The main aim of this work was to test a diffusion model to describe atmospheric freeze drying (AF... more The main aim of this work was to test a diffusion model to describe atmospheric freeze drying (AFD) and hot air drying (HAD) kinetics of different products. HAD (50 ºC and 2 ms-1) and AFD (-14 ºC, 2 ms-1) experiments were carried out for eggplant, apple and carrot cubes (side 10 mm). Kinetics were described using a diffusion model neglecting the external resistance to water transfer and the shrinkage of the samples. A good fit was obtained for AFD of apple and carrot, where assumptions considered in the model formulation were properly chosen.

The application of power ultrasound could constitute a way to improve traditional convective dryi... more The application of power ultrasound could constitute a way to improve traditional convective drying systems. There still exists a lack of knowledge on this technology in order to address industrial applications. The aim of this work was to identify the influence of the textural properties of different vegetable products on the ultrasonic assisted convective drying. For that purpose, experimental drying kinetics (40 ºC and 1 m/s) of different vegetable products (orange and lemon peel, carrot, potato and eggplant) were carried out applying different ultrasonic powers (0, 6, 12, 18, 25, 30 and 37 kW/m3). In every product, a similar diffusion model was used to identify an average effective diffusivity for the different ultrasonic powers. Product’s textural properties were assessed by Textural Profile Analysis (TPA). Linear relationships were established between the identified effective diffusivity and the applied ultrasonic power for the different products. The positive slopes of the li...

Dehydration constitutes a traditional preservation method for fruits and vegetables and it repres... more Dehydration constitutes a traditional preservation method for fruits and vegetables and it represents a very important operation in food processing. The way how water is removed from food affects the final product quality, thus the characteristics of dried products are dependent on the drying technique used. The main objective of the present study was to evaluate the effect of different drying techniques on the quality of dried eggplant. For this purpose, cubic samples (10 mm side) were obtained from the flesh of Spanish origin eggplants (Solanum melongena var. Black Enorma). Three different drying techniques were applied: hot air drying (HAD, 50 ºC and 2 m/s), atmospheric freeze drying (AFD, -14 ºC and 2 m/s) and vacuum freeze drying (VFD). The drying kinetics of HAD and AFD were determined by weighing the samples at preset times during the process. To evaluate the influence of drying method on the final quality of the product, rehydration kinetics of HAD, AFD and VFD samples were ...

Intermittent drying technology implements varying-time operating conditions to improve process en... more Intermittent drying technology implements varying-time operating conditions to improve process energy efficiency in comparison with other conventional convective drying techniques. One method of intermittent drying involves heating and resting periods. In heating periods, hot air removes the moisture and increases the material temperature by forced convection. In resting (or tempering) periods, the change of the temperature and moisture content takes place without heat supply by free convection. The mass transfer phenomena that take place during resting period may be modified by power ultrasound application. External resistance to mass transfer may be affected by pressure variations, oscillating velocities and microstreaming at the solid-gas interfaces. Internal resistance may be reduced by alternating expansion and compression cycles produced by ultrasound in the material and also through some effects on the interfaces of intercellular spaces, which may contribute to faster water d...

The final composition of cheese products constitutes one of their quality attributes and its know... more The final composition of cheese products constitutes one of their quality attributes and its knowledge in quality control is important. The measurement of ultrasonic velocity is a non-destructive technique, which allows the determination of foodstuff composition. Ultrasonic velocities in both cheese analogues and commercial cheese spreads were determined at different temperatures. The protein, fat and moisture contents of the samples ranged between 8.54 and 12.1 % (wb), 0.2 and 30.1 % (wb) and 57.5 and 81 % (wb), respectively. At 18ºC the ultrasonic velocity was not dependent on the cheese composition. The ultrasound velocity increased with the increase of fat content at temperatures lower than 18ºC and decreased for higher temperatures. From ultrasonic velocity measurements on cheese analogues, a model was developed to correlate the ultrasonic velocity, temperature and composition. This model allowed a good assessment of the composition of independent samples of cheese spreads.

Journal of Food Engineering, 2015

ABSTRACT The daily challenge involved in operating a process is the attainment of the objectives.... more ABSTRACT The daily challenge involved in operating a process is the attainment of the objectives. Process management requires the use of tools adapted to the system’s complexity. In order to obtain real time results, simplified mechanistic modelling offers a way to deal with this. To this end, carob pod (Ceratonia Siliqua, L.) kibbles extraction is addressed in this work. They are a source of different, valuable components and have a complex structure and a highly variable concentration of components. The components considered are sugars and soluble polyphenols. Obtaining the extracts with an optimal composition of a particular component, while avoiding or limiting other components in the extract, is a challenge to be addressed. Two steps can be considered: solubilization and diffusion, modelled by means of a first order reaction and by considering slab geometry. The optimal processing time and temperature are obtained by taking a particular kibble size and composition into account.