A review of microwaves for food processing

Abstract

Summary Ideas for the application of microwave heating to the processing of food are reviewed. A selection has been made of ideas for pasteurizing, sterilizing, defrosting, dehydrating, cooking and other applications that are described in the literature. Several are discussed to illustrate particular aspects and characteristics of microwave processing, and to try and show some reasons for the successes and failures. Microwave heating on its own has led to few commercially successful processes; however, when combined with conventional sources of heat, microwave heating appears to have greater potential, and has led to several successful processes.

Inactivation of Soybean Lipoxygenase by Microwave Heating: Effect of Moisture Content and Exposure Time

“…This value remained constant for approximately 30 set and then the temperature started rising again, at a slower rate. This agrees with Sale (1976) that during microwave heating of wet food the temperature rises .to lOO"C, then the continued generation of heat boils off free water. According to the same author, when the free water is gone there is nothing to hold the temperature at 100°C and the temperature can rise rapidly.…”

Mathematical analysis of microwave heating process

“…The shape of the temperature profile was maintained for the different heating times; as observed, microwave energy focus lies in the sphere center, and generates hot spots or maximum temperature values. This behavior was observed and described by previous authors (Ohlsson & Bengtsson, 1971;Sale, 1976). The numerical results followed the general behavior of experimental data, presenting very good agreement and low estimation error (average percentage relative error between predicted and experimental values was À2.46% ).…”

“…This phenomenon has been analyzed by many authors (Ayappa, Davis, Crapiste, Davis, & Gordon, 1991;Ayappa, Davis, Davis, & Gordon, 1992) because it has become one of the major drawbacks for application at domestic or industrial level. For instance, this uneven distribution produces dry and burned zones in products where in other zones, the minimum temperature required for processing is not reached (Sale, 1976). This worsens during sterilization since, being the method unable to guarantee lethality temperatures for microorganisms in all zones, it requires overheating in some zones to conduct a safe process thus causing quality losses.…”

The Use of Microwave Radiation Energy to Process Cereal, Root and Tuber-based Products

“…During heating of a moist product, the heat will be used to evaporate water and the temperature will be maintained at 100ºC. As soon as the free water is evaporated, product temperature can increase rapidly, with the risk of it burning (Sale, 1976).…”