5 research outputs found
Model-based investigation into atmospheric freeze drying assisted by power ultrasound
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.The authors acknowledge the financial support of the Spanish Ministerio de Economia y Competitividad (MINECO) and of the European Regional Development Fund (ERDF) through the project DPI2012-37466-CO3-03, the FPI fellowship (BES-2010-033460) and the EEBB-I-14-08572 fellowship granted to J.V. Santacatalina for a short stay at Politecnico di Torino.Santacatalina Bonet, JV.; Fissore, D.; Cárcel CarriĂłn, JA.; Mulet Pons, A.; GarcĂa PĂ©rez, JV. (2015). Model-based investigation into atmospheric freeze drying assisted by power ultrasound. Journal of Food Engineering. 151:7-15. https://doi.org/10.1016/j.jfoodeng.2014.11.013S71515
Influence of the ultrasonic power applied on freeze drying kinetics
© 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of the Scientific Committee of ICU 2015[EN] The atmospheric freeze drying (AFD) constitutes an interesting alternative to vacuum freeze drying providing products with
similar quality at lowest cost. However, the long process time needed represent an important drawback. In this sense, the
application of high intensity ultrasound can enhance heat and mass transfer and intensify the operation. In hot air drying
operation, the ultrasonic effects are dependent on the process variables such as air velocity, internal sample structure or ultrasonic
power applied. However, in AFD processes, the internal structure of material or the air velocity has not significant influence on
the magnitude of ultrasonic effects. The aim of this work was to determine the influence on drying kinetics of the ultrasonic
power applied during the AFD of apple. For that purpose, AFD experiments (-10ÂşC, 2 m/s and 15% relative humidity) of apple
slabs (cv. Granny Smith, 30 x 30 x 10 mm) were carried out with ultrasound application (21 kHz) at different power levels (0,
10.3, 20.5 and 30.8 kW/m3). The drying kinetics was obtained from the initial moisture content and the weight evolution of
samples during drying. Experimental results showed a significant (p<0.05) influence of the ultrasound application on drying.
Thus, drying time was shorter as higher the ultrasonic power applied. From modeling, it was observed that the effective diffusion
coefficient identified was 4.8 times higher when ultrasound was applied at the lowest power tested (10.3 kW/m3) that illustrated
the high intensification potential of ultrasound application in the AFD.The authors acknowledge the financial support of the Spanish Ministerio de EconomĂa y Competitividad (MINECO) and the European Regional Development Fund (ERDF) from the project DPI2012-37466-CO3-03 and Generalitat Valenciana from the project PROMETEOII/2014/005.Brines, C.; Mulet Pons, A.; GarcĂa PĂ©rez, JV.; Riera, E.; Cárcel CarriĂłn, JA. (2015). Influence of the ultrasonic power applied on freeze drying kinetics. Physics Procedia. 70:850-853. https://doi.org/10.1016/j.phpro.2015.08.174S8508537
Ultrasonically enhanced low-temperature drying of apple: Influence on drying kinetics and antioxidant potential
[EN] Low-temperature air drying represents an alternative means to hot air drying of better retaining the
sensory, nutritional and functional properties of foods. However, reducing the air temperature to figures
below the product s freezing point involves low drying rates, which largely places constraints on any
further industrial application. The main aim of this work was to evaluate the feasibility of using power
ultrasound to improve the low-temperature drying of apple, considering not only the kinetic effects
but also the influence on the antioxidant potential of the dried apple.
For that purpose, apple (Malus domestica cv. Granny Smith) cubes (8.8 mm side) were dried (2 m/s and
a relative humidity of under 10%) at low temperatures ( 10, 5, 0, 5 and 10 C) with (20.5 kW/m3) and
without ultrasound application. The drying kinetics were modeled by considering the diffusion theory,
negligible shrinkage and cubic geometry. In the dried apple, total phenolic and flavonoid contents and
antioxidant capacity were measured.
The application of power ultrasound sped up the drying kinetics at every temperature tested, achieving
drying time reductions of up to 77%, which was linked to the improvement in diffusion and convective
mass transport. In overall terms, ultrasound application involved a greater degradation of polyphenol
and flavonoid contents and a reduction of the antioxidant capacity, which was related to the cell
disruption caused by the mechanical stress of acoustic waves.The authors acknowledge the financial support of the Spanish Ministerio de Economia y Competitividad (MINECO), the European Union (FEDER) and the Generalitat Valenciana (from the projects DPI2012-37466-CO3-03, DPI2012-37466-CO3-02, PROMETEO/2010/062 and the FPI fellowship granted to J.V. Santacatalina).Santacatalina Bonet, JV.; RogrĂguez, Ă“.; Simal, S.; Cárcel CarriĂłn, JA.; Mulet Pons, A.; GarcĂa PĂ©rez, JV. (2014). Ultrasonically enhanced low-temperature drying of apple: Influence on drying kinetics and antioxidant potential. Journal of Food Engineering. 138:35-44. https://doi.org/10.1016/j.jfoodeng.2014.04.003S354413
Ultrasonic monitoring of lard crystallization during storage
[EN] This work addresses the use of ultrasonics as a non-destructive technique with which to monitor lard crystallization during cooling and storage. The ultrasonic velocity was measured during both the isothermal crystallization of lard (at 0, 3, 5, 7, 10 and 20 degrees C) and during the non-isothermal crystallization. In addition, lard crystallization was also studied through Differential Scanning Calorimetry (DSC) and instrumental texture analysis (penetration tests). The measurement of the ultrasonic velocity allowed the bulk crystallization to be detected. The evolution of the ultrasonic velocity and the textural measurements during isothermal crystallization showed two steep increases, which may be explained by the two fractions of triglycerides found in DSC thermograms. At 7, 10 and 20 degrees C the second fraction did not crystallize within the first 11 days of storage. A two-step crystallization model based on the Avrami model was used to properly describe (% var > 99.9 and RMSE < 1.99 m s(-1)) the relationship between the ultrasonic velocity and the isothermal crystallization time. In addition, a model was developed to estimate the percentage of solid fat content during isothermal crystallization. Therefore, it may be pointed out that ultrasonic techniques could be useful to monitor the crystallization pattern of complex fats during long periods of storage. (C) 2010 Elsevier Ltd. All rights reserved.The authors acknowledge the financial support from the "Ministerio de Ciencia e Innovacion" in Spain (Project AGL 2007-65923-C02-02).Santacatalina Bonet, JV.; GarcĂa PĂ©rez, JV.; Corona JimĂ©nez, E.; Benedito Fort, JJ. (2011). Ultrasonic monitoring of lard crystallization during storage. Food Research International. 44(1):146-155. https://doi.org/10.1016/j.foodres.2010.10.048S14615544