A susceptor is a material used for its ability to absorb electromagnetic energy and convert it to heat (which in some cases is re-emitted as

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

thermal radiation). The electromagnetic energy is typically radiofrequency or

microwave Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequency, frequencies between 300&n ...

radiation used in industrial heating processes. In the consumer world, many microwave cooking tools as well as some disposable cooking vessels used with induction heating employ susceptors.

Operation

In microwave cooking, susceptors are built into paper packaging of certain foods, where they absorb microwaves which penetrate the packaging. This process raises the susceptor patch temperature to levels where it may then heat food by conduction or by infrared radiation. * Conduction heating occurs with good thermal contact between the susceptor and food. Because of the lower temperatures there is less browning, but more than if there were no susceptor at all. * If there is an air gap (or at least, poor thermal contact) between the susceptor and food, the susceptor will heat to a much higher temperature (due to its smaller effective heat capacity when in poor contact with food), and, at these higher temperatures, will radiate strongly in the

. This infrared radiation then shines onto the food below or next to the susceptor, causing a "broiling" type effect (high skin heating) due to lower ability of infrared to penetrate foods, vs. microwaves. Conversion of some microwave energy to infrared is particularly useful for foods which require a large amount of crust-browning from infrared, such as frozen pies.

Design and use

Susceptors are usually made of metallised film,

ceramic A ceramic is any of the various hard, brittle, heat-resistant, and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcela ...

s or

metal A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated wit ...

s (such as

aluminium Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

flakes). Susceptors meant to heat foods by direct conduction may be seen in the gray lining of packaging directly holding the food, and generally in good contact with it. For this reason, products meant to be browned via susceptor-generated thermal radiation carry instructions to microwave the food while still inside its packaging. A typical example is the paper-susceptor–lined dish directly holding a microwaveable pot pie or casserole. This is useful for crisping and browning foods, as well as concentrating heat on the oil in a microwave popcorn bag in order to melt it rapidly. Among the first microwave susceptors marketed were those from the mid-1980s in a product called McCain Micro Chips by

McCain Foods McCain Foods Limited is a Canadian multinational frozen food company established in 1957 in Florenceville, New Brunswick, Canada. It is the world's largest manufacturer of frozen potato products, with 1 in 4 french fries in the world being a ...

. It consisted of a susceptor sheet which cooked French fries in a

microwave oven A microwave oven, or simply microwave, is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. This induces Dipole#Molecular dipoles, polar molecules in the food to rotate and ...

. These sheets are currently used in several types of

packaging Packaging is the science, art and technology of enclosing or protecting products for distribution, storage, sale, and use. Packaging also refers to the process of designing, evaluating, and producing packages. Packaging can be described as a coo ...

for heating and cooking products in microwave ovens. Care in package design and use is required for proper

food safety Food safety (or food hygiene) is used as a scientific method/discipline describing handling, food processing, preparation, and food storage, storage of food in ways that prevent foodborne illness. The occurrence of two or more cases of a simi ...

. A "crisping sleeve" is a device made of paperboard and affixed with a susceptor used both as a rigid container to support the food items within and to focus heat on the foodstuff. They are generally intended for a single use.

Hot Pockets Hot Pockets is an American brand of microwaveable turnovers generally containing one or more types of cheese, meat, or vegetables. Hot Pockets was founded by Chef America Inc. Since April 20, 2002, they have been produced by Nestlé. Histor ...

were an example of a product which used crisping sleeves.

Microwave crisper pan

Microwave crisper pans and trays convert microwave into infrared to heat food.

References

External links

"Susceptor heating" on commercial website

Cooking appliances Packaging materials Electromechanical engineering Microwave technology American inventions

Operation

Design and use

Microwave crisper pan

See also

References

Further reading

External links