A model to design high-pressure processes towards an uniform temperature distribution

ArticleinJournal of Food Engineering 78(4):1463-1470 · February 2007with6 Reads
DOI: 10.1016/j.jfoodeng.2006.01.020
A mathematical model has been developed to describe the phenomena of heat and mass transfer taking place during the high-pressure treatment of foods. It has proved that convection currents in the pressure medium play an important role in the thermal evolution of the processed samples especially when the filling ratio in the pressure vessel is low. This model shows to be an extremely useful toot to design high-pressure processes seeking a uniform temperature distribution. (c) 2006 Elsevier Ltd. All rights reserved.
    • "Insulated materials with compression heating properties (then that the temperature of the insulation increases as the product is pressurized ) prevent heat transfer from the product being treated to the surrounding medium and to the cooler pressure vessel wall, with a substantial increase in efficiency [54]. Moreover, industrial-scale systems result in greater efficacy of bacterial inactivation than pilot-scale ones because compression heating persists for a longer time [52, 118] . A strong coupling also exists between spatial concentrations of surviving microorganisms and low-temperature zones of packaging materials. "
    [Show abstract] [Hide abstract] ABSTRACT: High Pressure Processing (HPP) allows decontamination of foods with minimal impact on their nutritional and sensory features. The use of HPP to reduce microbial loads has shown great potential in the muscle-derived food industry. HPP has proven to be a promising technology and industrial applications have grown rapidly, especially in the stabilization of ready-to-eat meats and dry-cured products, satisfying the demands of regulatory agencies such as the United States Department of Agriculture-Food Safety and Inspection Services (USDA-FSIS). Applications also extend to seafood products and HPP has been used in a wide range of operations, from non-thermal decontamination of acid foods to combined pressure-heating treatments to inactivate pathogenic bacteria, pressure supported freezing and thawing, texturization, and removal of meat from shellfish and crustaceans. Research has also been conducted on the impact of the technology on quality features. Processing-dependent changes in muscle foods include changes in colour, texture and water-holding capacity, with endogenous enzymes playing a major role in the phenomena. This review summarizes the current approaches to the use of high hydrostatic pressure processing, focusing mainly on meat, meat products and seafood. Recent findings on the microbiological, chemical and molecular aspects, along with commercial and research applications, are described. © 2011 by Nova Science Publishers, Inc. All rights reserved. All rights reserved.
    Full-text · Dataset · Jul 2015 · Applied Mathematics and Computation
    • "These losses have been estimated to be more than 40 to 50% in the tropics and subtropics. Post-harvest losses of fruits and vegetables in developing countries is therefore of serious concern (Otero et al, 2007). Moreover, in many developing countries only a limited quantity of fruit and vegetable products are produced for local markets or for exportation due to lack of machinery and infrastructure. "
    [Show abstract] [Hide abstract] ABSTRACT: Cooling is an important task in the food industry. Harvested agricultural produce is subjected to precooling before packaging, processing and transportation. Heat moves to surface of product in a mixed-mode of conduction and convection, and from surface to environment by convection. Therefore, estimation of thermal properties (like thermal diffusivity) is important to analyze heat transfer phenomena and design of refrigeration and processing equipments. This work presents a simple method to estimate thermal diffusivity variations of selected regular shaped food products subjected to natural convection cooling. Experimental investigations were carried out on fruits and vegetables. Samples chosen were melon, orange and potato (spherical) and bottle gourd (cylindrical). The experimental setup consists of a deep-freezer maintained at -10˚C and 1 atm. The variation of temperature within a product is measured along the radial direction using copper-constantan thermocouples. The output of thermocouples is read on a digital microvolt meter. The temperature of thermocouples was recorded at regular intervals of 5 minutes. Variation of surface temperature is obtained based on radial temperature profiles. Thermal diffusivity (α) variation is calculated for each time interval using one-dimensional Fourier's equation. Correlation for thermal diffusivity as a function of surface temperature is developed for each of the sample.
    Full-text · Conference Paper · Aug 2014 · Applied Mathematics and Computation
    • "Also a numerical solution in both 1D (using radial coordinates) and 2D (using cylindrical coordinates) is calculated using the FEM solver COMSOL Multiphysics 3.5a. In [5,9] similar, although more complex, models were solved numerically using this commercial software, and validated by comparing to experimental data. Our model is a simplification of the models proposed in those papers, and not based on a real experiment, so we chose a numerical solution solved with COMSOL rather than a comparison to experimental data. "
    [Show abstract] [Hide abstract] ABSTRACT: Nowadays, consumers look for minimally processed, additive-free food products that maintain their organoleptic properties. This has led to the development of new technologies for food processing. One emerging technology is high hydrostatic pressure, as it proves to be very effective in prolonging the shelf life of foods without losing its properties. Recent research has involved modelling and simulating the effect of combining thermal and high pressure processes (see Denys et al. (2000) [3], Infante et al. (2009) [5], Knoerzer et al. (2007) [6], Otero et al. (2007) [9]). The focus is mainly on the inactivation of certain enzymes and microorganisms that are harmful to food. Various mathematical models that study the behaviour of these enzymes and microorganisms during a high pressure process have been proposed (see Infante et al. (2009) [5], Knoerzer et al. (2007) [6]). Such models need the temperature and pressure profiles of the whole process as an input. In this paper we present two dimensional models, with different types of boundary conditions, to calculate the temperature profile for solid type foods. We give an exact solution and propose several simplifications, in both two and one dimensions. The temperature profile of these simplified two and one dimensional models is calculated both numerically and analytically, and the solutions are compared. Our results show a very good agreement for all the approximations proposed, and so we can conclude that the simplifications and dimensional reduction are reasonable for certain parameter values, which are specified in this work.
    Full-text · Article · Jan 2014
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