Microwave technologies are used in such processes as drying, sterilization, pasteurization, thawing, blanching, and cooking. During the process of dehydration, the main objective is to remove water from a product. In sterilization and pasteurization processes, microwave systems are specially designed to raise the temperature of the product to a specific level so as to kill all pathogens while maintaining integrity of the product. During blanching, the product is heated up and cooled down instantaneously and during cooking the temperature of the product is maintained on an elevated level for a long time. Microwave drying can be used successfully to dry wood, industrial coatings, ceramics, and various types of powdered materials.
The food industry is one of the main sectors where microwave heating is used. Drying of potato chips was one of the first application for microwave systems in the food industry. Currently, microwave drying is also used for such products as pasta, potatoes, and fruit juice concentrates.
Microwave ovens are also used for baking bread. By quickly raising the temperature, microwave baking enables quick deactivation of enzymes inside the dough, which prevents decomposition of starch. Preliminary baking, especially of bacon, has also been increasingly popular. During grilling, bacon loses large quantities of fat, which results in loss of weight and shrinkage of the end product. By using microwave systems, which reduce the processing time, those shortcomings are minimized.
CHEMICAL AND PHARMACOLOGICAL INDUSTRIES
The chemical and pharmacological industries are among the most important customers, which use microwave heating for catalyzing various chemical reactions and synthesis of organic compounds, including many medicines. Currently this is one of the main methods for heating of chemical reactions in laboratories. It not only reduces the reaction time, but also reduces the number of side reactions and increases the effectiveness and repeatability of processes. In the analytical chemistry sector, microwave heating systems are used to incinerate and mineralize samples, testing dry method measurements, and extraction. Of note is the fact that extraction performed with microwave equipment not only takes place faster, but also enables a significant reduction of reagent consumption.
Microwave drying systems are also successfully used in the ceramic industry where removal of solvents and moisture are very important processes. In the plastics industry, microwave heating is used for conducting polymerization processes, e.g. ring-opening polymerization used in production of aliphatic polymers, polycondensation used in production of polyamides and polyesters, and free radical polymerization used in production of polystyrene.
MINING AND METALLURGY
In the mining industry, microwave heating systems are used to separate certain minerals from ores, e.g. gold. This technology enables a significant reduction of the ore milling time, as well as wear of machines and equipment during the milling process, and an increase of efficiency and cleanliness of the mineral obtained. Microwave heating systems are also used to purify coal ores from the pyrite they contain. They are also used successfully in the metallurgical industry.