Instant Controlled Pressure Drop (DIC) Technology in Food Preservation: Fundamental and Industrial Applications

Alternative to conventional processes, many innovative techniques have been studied to preserve the nutritional quality and to protect food from deterioration. This chapter represents the principles and the applications of the instant controlled pressure drop (DIC) process in food drying and decontamination. This process is considered as a highly appropriate HTST-type treatment induced by subjecting the material to saturated steam, during a short time, followed by an instant pressure drop leading to auto evaporation of water, product texturing, and cooling. This effect results in improved drying of foods and in killing of the vegetative bacteria and/or spores with no impact on thermosensitive molecules or on the product quality. A wide range of foods and pharmaceutical products were effectively treated by DIC technology at both laboratory and industrial scales

Microwave Heating for Food Preservation

Since food is generally of low thermal conductivity, heating by conventional methods remains relatively slow. Thanks to its volumetric and rapid heating, microwave (MW) technology is successfully used in many applications of food processing. In this chapter, fundamental principles of MW heating are briefly presented. MW drying and MW microbial decontamination are extensively reviewed as innovative methods for food preservation. However, the complex interactions between microwaves and materials to be heated are not yet sufficiently controlled. Moreover, MW heating heterogeneity and thermal runaway are the main drawbacks of this technology. Several methods have been proposed and investigated in the literature to overcome these problems in order to assure the microbiological safety and quality of food products

Thermal Food Engineering Operations

International audienc

Model-Based Settings of a Conveyorized Microwave Oven for Minced Beef Simultaneous Cooking and Pasteurization

12th IFAC Symposium on Computer Applications in BiotechnologyThe International Federation of Automatic Control16-18, 2013, December. Mumbai, IndiaInternational audienceA major drawback of microwave processing is the heterogeneity of treatment, which preventsfrom a plenty benefit of its flexibility and rapidity. Most of time, this operation is realized in continuousprocesses, composed of a series of microwave generators with adjustable power. In this paper is proposeda methodology leading to an optimal setting of these powers in order to warrant the expectedmicroorganisms’ inactivation during simultaneous cooking and pasteurization, while preserving quality.It consists in minimizing a multicriteria formulation including hottest and coldest points on the first hand,and final logarithmic inactivation on the other one. The simulation model is composed of a reduction ofthe heat equation via a finite volume scheme with a source term deduced from appropriate closed-formsolutions of the Maxwell’s equations, whereas the non-isothermal inactivation is described by theGeeraerd model. The methodology is carried out by considering treatment of minced beef

Modeling and Simulation of Wheat Grains Ozonation

In order to improve the ozonation process efficiency, reliable modeling and simulation tools are needed. In this study, wheat grains were exposed to ozone gas for 45 min at an applied dose of 3.5 g O3/kg of wheat in a semi-industrial fixed-bed reactor. The consumed and the residual ozone were measured continuously. These values were fit, at a first step, to a two consecutive reactions kinetic model. A second part of our work led us to develop and assess a new simplified one reaction model. Cuticle layer hypothesis was later adopted to improve our original model. Using Matlab ® , the reactions kinetics and mass transfer coefficients of these models were determined. Our kinetic model predicted the experimental data with high accuracy. In addition, a computational fluid dynamics (CFD) model was developed in COMSOL ® v.5.3a in order to study the gas flow inside the reactor. This new approach is a first step to develop a comprehensive coupled model involving the ozonation reactions as well as the ozone diffusion in a porous medium

Modeling and Simulation of Wheat Grains Ozonation

In order to improve the ozonation process efficiency, reliable modeling and simulation tools are needed. In this study, wheat grains were exposed to ozone gas for 45 min at an applied dose of 3.5 g O3/kg of wheat in a semi-industrial fixed-bed reactor. The consumed and the residual ozone were measured continuously. These values were fit, at a first step, to a two consecutive reactions kinetic model. A second part of our work led us to develop and assess a new simplified one reaction model. Cuticle layer hypothesis was later adopted to improve our original model. Using Matlab ® , the reactions kinetics and mass transfer coefficients of these models were determined. Our kinetic model predicted the experimental data with high accuracy. In addition, a computational fluid dynamics (CFD) model was developed in COMSOL ® v.5.3a in order to study the gas flow inside the reactor. This new approach is a first step to develop a comprehensive coupled model involving the ozonation reactions as well as the ozone diffusion in a porous medium

Microwave inactivation of Escherichia coli K12 CIP 54.117 in a gel medium: Experimental and numerical study

International audienceThis study evaluates the efficiency of the inactivation of Escherichia coli K12, entrapped within calcium alginate gel, by microwave processing compared to a conventional approach i.e. by heating in a water bath. Microbial thermal inactivation equations coupled with heat transfer and Maxwell's equations are integrated into a 3D Finite Elements model under dynamic heating conditions. Water bath microbial inactivation experimental data are exploited for performing parameter identification of a non-linear microbial model, and the Calcium alginate gel's dielectric properties were numerically estimated. The coupled model provides a very good fitting to the experimental results. The simulation have shown uneven temperature distribution during microwave heating which may interpret its lower inactivation efficiency comparing to the conventional water bath treatment. This study also demonstrates the reliability of the coupled modeling approach to estimate the efficiency of the microbial inactivation, despite the thermal heterogeneity inherent in the microwave treatment

Holding time effect on microwave inactivation of Escherichia coli K12: Experimental and numerical investigations

International audienceNon-uniform microwave heating is the main drawback in assuring the microbiological safety of food products. The focus of this study is to compare the efficiency of the inactivation of Escherichia coli K12, entrapped within calcium alginate gel, during a microwave and a water bath processing with a holding phase at set points of 55 °C and 57 °C. Microbial thermal inactivation equations coupled with heat transfer and Maxwell’s equations are integrated and solved numerically via a finite element method to interpret the experimental results. The water bath microbial inactivation parameters are estimated by using inverse techniques and then applied to the microwave treatment. The simulated values are in good agreement with the experimental measurements. The simulation shows uneven temperature distribution during microwave heating which leads to a lower inactivation efficiency of microwave treatment. In this study, the holding phase did not help to homogenize the temperature distribution within the sample. This model can be used to improve the design of microwaves systems and to develop this process as a reliable pasteurization method