Susceptor

Susceptors may be added to "crisping sleeves" inconvenience foodssuch asHot Pockets.

Asusceptoris a material used for its ability to absorbelectromagnetic energyand convert it to heat (which in some cases is re-emitted asinfraredthermal radiation). The electromagnetic energy is typicallyradiofrequencyormicrowaveradiation used in industrial heating processes, and also inmicrowave cooking.

Operation

Inmicrowave 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 byconductionor byinfrared 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 effectiveheat capacitywhen in poor contact with food), and, at these higher temperatures, will radiate strongly in theinfrared.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 ofmetallised film,ceramicsormetals(such asaluminiumflakes).

The susceptor (which may be located on examination by its gray or blue-gray color, which is different from paper) is the reason products meant to be browned via susceptor-generatedthermal radiationcarry instructions to microwave the food while still inside its packaging.

Susceptors meant to heat foods by direct conduction, where less browning will occur, may be seen in the gray lining of packaging directly holding the food and in good contact with it. A typical example of the latter is the paper-susceptor–lined dish directly holding a microwaveablepot pieorcasserole.

Susceptors built into packaging create high temperatures in amicrowave oven.This is useful for crisping andbrowningfoods, as well as concentrating heat on the oil in amicrowave popcornbag (which is solid at room temperature) in order to melt it rapidly.

Among the first microwave susceptors marketed were those from the mid-1980s in a product calledMcCain Micro ChipsbyMcCain Foods.It consisted of a susceptor sheet which cookedFrench friesin amicrowave oven.These sheets are currently used in several types ofpackagingfor heating and cooking products in microwave ovens. Care in package design and use is required for properfood safety.

A "crisping sleeve" is a device made ofpaperboardand 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 Pocketsis an example of a product which uses crisping sleeves.

Microwave crisper pan

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

See also

• Microwave heat distribution

Further reading

• Kumari, Saroj; Kumar, Rajeev; Agrawal, Pinki R.; Prakash, Shiv; Mondal, D.P.; Dhakate, Sanjay R. (October 2020)."Fabrication of lightweight and porous silicon carbide foams as excellent microwave susceptor for heat generation".Materials Chemistry and Physics.253:123211.doi:10.1016/j.matchemphys.2020.123211.S2CID224862524.
• Yam, K. L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009,ISBN978-0-470-08704-6
• "What does the cardboard plate in your microwave do?".Coolblue B.V.Retrieved6 April2023.
• "1981 Corning Microwave Crisper ad".eBay.Archived fromthe originalon 6 April 2023.Retrieved6 April2023.

External links

• "Susceptor heating" on commercial website
• Susceptor heating film on fast food package with carbon-based coatings