Marc Regier

The Microwave Processing of Foods

Part 1 Principles: Introducing microwave processing of food: Principles and technologies Dielectric properties of foods Measuring the dielectric properties of foods Microwave heating and the dielectric properties of foods Microwave processing, Nutritional and sensory quality. Part 2 Applications: Microwave technology for food processing: an overview Baking using microwave processing Drying using microwave processing Blanching using microwave processing Thawing and tempering using microwave processing Packaging for microwave foods. Part 3 Measurement and process control: Measuring the heating performance of microwave ovens Measuring temperature distributions during microwave processing Improving microwave process control Maximising uniform head distribution in microwave heating.

Development of a Model Food for Microwave Processing and the Prediction of its Physical Properties

Although microwave processes in the food industry such as microwave pasteurisation or microwave drying are already in use, most of their optimisation is still based on trial-and-error. To model these processes, knowledge of different physical properties of the food material is indispensable. In order to guarantee constant product properties a model food was developed imitating real food properties and showing physical and microbial stability over several months. In this manuscript the prediction of these physical properties and the comparison of the model food with a real food will be shown.

Dielectric properties of emulsions and suspensions: mixture equations and measurement comparisons.

Dielectric properties of water-in-oil emulsions, oil in water emulsions and limestone-in-water suspensions have been measured at 2.45 GHz by an open-ended coaxial-line probe. The results were compared to various equations for the dielectric properties of mixtures. The equation by Fricke and Mudgett describes best the behavior of oil-in-water emulsions and limestone in water suspensions. For water-in-oil emulsions the equation by Lichtenecker and Rather gives the best results.

Dielectric Spectroscopy and Principal Component Analysis as a Method for Oil Fraction Determination in oil-in Water-Emulsions with Varying Salt Content

Important parameters, that define the physical properties of an emulsion, are the concentrations of the constituents. In the case of a continuous production of emulsions an exact and fast control of the fractions is essential to ensure a constant product quality. Whereas the method of sample drying, weighing and chemical analysis is too slow for an online product control, the dispersed phase fraction determinition by density only works for two-component-systems. For the purpose of more practical emulsions with possible variations in both, the dispersed phase fraction and the salt content, in this work dielectric spectroscopy in combination with principal component analysis is studied. Introduction The properties of an emulsion are strongly dependent on the concentratations of constituents. As an example, the rheological and the sensory properties depend on the fraction of the dispersed phase (here the oil phase, of an oil-in-water emulsion). Emulsions in practice often consist of more than two chemical species. It is therefore not sufficient to chracterise the emulsions by the measurement of its dielectric properties at one frequency. For a sufficient characterisation the measurement of the dielectric constant over a frequency range is necessary, yielding a large data set, difficult to analyse. One possible method for its analysis is the principal factor analysis, which is a mathematical-statistical technique [1]. It was first used in the behavioral sciences