Applications of microwave fields in food technology: processing, preservation and extraction

Abstract

Microwave radiation, as a method of heat supplying, is not so far widely used in food industry. However, this method is promising because of the moisture present in food products, which is heated extremely intense. A number of scientific studies confirm that microwave radiation significantly intensifies processes of dehydration and extraction. This study presents the results of using MWAE – the microwave assisted extraction, – in the production of coffee, rosehips, medicinal herbs and other extracts. The dependencies of the extraction kinetics, thermograms and results of the study of obtained extracts qualitative parameters are presented. Different types of extraction units were used for different products: open vessel type, closed vessel type, operating at atmospheric and at reduced pressure. The extracting from ground coffee shows high values of mass transfer coefficients: [5.8, ... 8,8∙10-8] m/s, which indicates a high degree of the process intensification in comparison with methods of battery extraction. The process temperature did not exceed 100 °C, so there are no cellulose hydrolysis processes, which reduce the quality of the coffee extract. An extractor of a closed type was used for extracting from rose hips. The extraction was carried out under reduced pressure. Analysis of the obtained extract showed a high content of vitamin C and beta-carotene, compared with the extracts obtained in the thermostat.