Microwave and Radio Frequency energy is used extensively for heating foods as it allows heat to be rapidly, efficiently and controllably deposited in foods which may be easily burnt or spoiled by conductive heating. Conduction and convection heating use high-temperature gradients and / or hot surfaces. For microwave and RF heating, depending on the composition of the food and the proper design of the equipment, the food can be very uniformly heated as the electromagnetic field can penetrate throughout the volume of the food.
Microwave NZ has a range of standard-design food processing equipment and also supplies custom equipment tailored to your specific needs, budget, and specification. Contact us to discuss your problems, ideas or needs.
Pasteurising packaged products, e.g., breads and muffins, whole fruit and vegetables or portions, and meat products such as salami, jerkies
Thawing of frozen foods, e.g., fish, meat, butter, margarine, cheese
Tempering or melting of food ingredients, e.g., butter, edible fats, confectionary, chocolate
Improving baking ingredients, e.g., wheats, grains, flour, glutens
De-fatting, fat melting, and sterilizing meat and animal products
Cooking and roasting, e.g., coffee, cheese, roux and sauces
Uses / Applications
It is the unique ability of electromagnetic waves (including Microwaves and Radio Frequency waves) to penetrate deeply into many materials that gives the opportunity to efficiently deposit heat in useful arrangements, or to measure many valuable material properties. Unlike surface measurement techniques, measurements taken over the whole of the object or material give an accurate picture of the substance, especially when "sensing" materials with complex structure. With "heating" applications there are even more opportunities to overcome the limitations of ordinary conventional heating (where heat must "dawdle in" towards the centre from the surface).
Microwave NZ designs and supplies both "heating" systems and "sensing" systems for industrial, scientific, and educational processes and applications.
Here are some recent activities and examples:
Sensors and sensing
Microwaves and Radio Frequency waves are used extensively to measure or "sense" certain properties of materials. The main advantages of using Microwave and Radio Frequency compared to many conventional measurement methods are that measurements can be made rapidly, in-line, non-destructively, with minimal sample preparation, and can obtain the properties of the whole object including the interior. Compared to light-based sensing methods (e.g., infrared, UV), which share some of the above benefits, Microwave and Radio Frequency waves penetrate a long way into many materials meaning the "sensed" volume is relatively large. Light-based methods measure only the surface of the material - microwave and RF often require no sample surface preparation.
Microwave NZ has developed a number of sensors for measuring the properties of materials in-line on conveyors, in pipes or for smaller batch samples. The choice of Microwave or Radio Frequency largely depends on the material and material property to be measured. Microwave NZ designs and produces both Microwave and RF sensors. Contact us to discuss your problems, ideas or needs.
Microwave and Radio Frequency sensors have been used successfully to measure:
Moisture content and density of grain, e.g., corn, soybeans, wheat, rice
Moisture content and density of wood and wood products, e.g., rough-sawn timber, woodchips, pelletized biomass, MDF, planks / boards
Moisture content of powders, e.g., food powders, pharmaceuticals
Salt and fat content of dairy products, e.g., butter, margarine, cheese, cheese-curd
Some properties of gases and vapours
Properties as a function of depth for soils, etc.
Rock, mineral, and soil processing
Microwave and Radio Frequency waves can be used to selectively heat regions within rocks and minerals such as along grain boundaries or within cracks, fissures and fracture lines. Doing this can significantly reduce the amount of energy required to further process rock samples, mined rocks, and minerals.
Microwave and RF energy can be used to melt asphalt for resealing or recycling roading surfaces.
Some soils can be sterilized using microwave and / or RF volumetric heating. Soil heating can also be used for remediation by reducing the concentration of pollutants.
Microwave NZ can supply custom equipment tailored to your specific needs, budget, and specification. Contact us to discuss your problems, ideas or needs.
De-fatting meats and animal products
Many materials that were once seen as waste are nowadays being further processed into useful products. One example is in the meat industry, where meat scraps and offcuts with a high percentage fat can be made leaner by microwave or radio frequency treatment. Microwave NZ's de-fatting systems separate the meat and fat into two separate streams. The leaner meat is a higher value product and an additional income stream can be generated from fat sales. By using microwave or radio frequency, the temperature can be precisely controlled, allowing the fat to be removed very efficiently causing minimum damage to the proteins.
Microwave NZ has standard-design de-fatting equipment which can be tailored to your specific needs, budget, and specification. Contact us to discuss your problems, ideas or needs.
Similar equipment can be used to sterilize infected meats and harvest valuable fat.
Some scientific experiments require rapid uniform heating of non-geometrically shaped objects, e.g., apples, and conventional heating systems are not able to do this. By using a radio-frequency generator with carefully designed electrodes, heat can be very uniformly deposited into non-geometrically symmetric items. Examples of such items are:
Stone fruit, e.g., apricots, nectarines, mangos, peaches
Pip fruit, e.g., apples, pears
Large berry fruit, e.g., persimmons, strawberries
Vegetables, e.g., carrots, parsnips, pumpkin and squash, potatoes
Rocks, minerals, and fabricated building materials
Plastic composites and synthetic building materials
Microwave and RF energy can be used to assist chemical processes that require precise control of heat deposition, heating rate, and temperature.
Microwave NZ designs and builds Microwave and Radio Frequency equipment for laboratories (both within universities and government research institutes) around the world. We have a strong research and scientific background and understand the needs of research institutes. Educational discounts are given as appropriate. Contact us to discuss your problems, ideas or needs.
Drying / curing
Microwave and Radio Frequency equipment can dry materials very quickly, unlike conventional oven drying which is often the rate-limiting aspect of a process. The ability to heat the areas of higher moisture (even when these are deep within the object or material) sets up a diffusion gradient to move moisture to the surface of the object or material where it can be evaporated. Without this internally deposited heat, the rate of diffusion of moisture through the material can be very slow, particularly in the latter stages of drying. In addition, microwave and RF waves often open diffusion paths for the moisture that would not otherwise exist.
Some materials, e.g., cheese curd, when subject to slight volumetric warming with microwaves or RF waves will very efficiently "shed" moisture while requiring only a fraction of the normal latent-heat-of-vaporisation energy. It is believed that the proteins "tighten" and squeeze out significant moisture.
Microwave NZ has can supply drying and curing equipment tailored to your specific needs, budget, and specification. Contact us to discuss your problems, ideas or needs.
Cure ceramics, rubber, glue, and other adhesives
Dry food products such as meat, milk powders, fruits, curds
Dry textile products and carpets
Dry and cure wood and wood products such as MDF (medium density fibreboard)
Heat / cure synthetic materials such as papers, cardboards, building products
Dry pharmaceutical products
Pressure / vacuum processing
Both pressure and vacuum processing require good mechanical design and a fundamental understanding of the properties of electromagnetic fields within pressure or vacuum cavities.
Vacuum processing: The processing time of vacuum freeze dried foods or other materials can be reduced by using Microwave and Radio Frequency heating. Freeze drying is performed under high vacuum levels by sublimation where the ice is directly converted to vapour without passing through the liquid phase. Conventional freeze drying is a slow process as the amount of ice removed decreases exponentially with time when heat is deposited only on the surface of the object by infrared heating. By using electromagnetic energy to slightly "warm" the interior regions of the food, the freeze drying process can be considerably accelerated.
Pressure treatments: Any heat treatment of foods and other water-containing materials requiring temperatures above 100 C must be performed at pressures above one atmosphere. In addition, some specific chemical reactions require high pressure.
Microwave NZ has can design and supply pressure and vacuum processing equipment tailored to your specific needs, budget, and specification. Contact us to discuss your problems, ideas or needs.
5kW 2450MHz Microwave generator with "bowl" applicator for food processing.
Microwave in-line sensor for measuring material properties.
10kW 27.12MHz RF generator for mineral processing.
30kW 922MHz Microwave generator and cavity for de-fatting meat.
1kW 40.68MHz RF generator with auto-tuning for laboratory use on specific-shaped items.
8kW 2450MHz Microwave generator and applicator for glue curing.
3kW 2450MHz Microwave pressure vessel.
Timber and wood processing
Timber and other wood products can be readily heated with Microwave or Radio Frequency energy. Proper design of the electromagnetic equipment can give very even heating throughout the wood
Microwave NZ has a range of standard-design wood processing equipment and also supplies custom equipment tailored to your specific needs, budget, and specification. Contact us to discuss your problems, ideas or needs.
Dry and preheat machined wood planks
Pyrolyse or decompose wood chips, pellets, sawdust, cellulose, thinnings and other biomass to produce transport bio-fuels, activated carbon, and valuable chemicals such as bio-oils
Laminate beams and other manufactured timber-derived building materials
Dry paper- or veneer-based laminates such as cardboards, plywoods, plasterboards, and faced-composite boards
Tempering / Thawing
Microwave and Radio Frequency is used extensively for tempering and thawing foods as it allows heat to be rapidly, efficiently and uniformly deposited throughout. This is unlike conventional thawing methods which either apply heat non-uniformly (and therefore slowly) or immerse the frozen products in water with resultant product loss from dissolved protein and problematic disposal of the water. With the proper design of the microwave applicator or the radio frequency electrodes, the material can be uniformly heated whether packaged in cartons or un-packaged, e.g., pork bellies, chicken or lamb products, or even meat before de-boning.
Microwave NZ can design and build tempering and thawing equipment tailored to your specific needs, budget, and specification. Contact us to discuss your problems, ideas or needs.
Thaw and temper edible fats such as butter, margarine, shortenings
Thaw frozen meat products, e.g., fish blocks, beef, pork bellies, bacon, offal
Temper chocolates and patisserie creams