Material used to convert electromagnetic energy to heat
Susceptors may be added to "crisping sleeves" in
convenience foods
such as
Hot Pockets
.
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
thermal radiation
). The electromagnetic energy is typically
radiofrequency
or
microwave
radiation used in industrial heating processes, and also in
microwave cooking
.
Operation
[
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]
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
infrared
. 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
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]
Susceptors are usually made of
metallised film
,
ceramics
or
metals
(such as
aluminium
flakes).
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-generated
thermal radiation
carry 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 microwaveable
pot pie
or
casserole
.
Susceptors built into packaging create high temperatures in a
microwave oven
. This is useful for crisping and
browning
foods, as well as concentrating heat on the oil in a
microwave popcorn
bag (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 called
McCain Micro Chips
by
McCain Foods
. It consisted of a susceptor sheet which cooked
French fries
in a
microwave oven
. These sheets are currently used in several types of
packaging
for heating and cooking products in microwave ovens. Care in package design and use is required for proper
food safety
.
[1]
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.
[2]
They are generally intended for a single use.
[3]
Hot Pockets
is an example of a product which uses crisping sleeves.
Microwave crisper pan
[
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]
Microwave crisper pans and trays covert microwave into infrared to heat food.
[4]
[5]
See also
[
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]
References
[
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]
Further reading
[
edit
]
- 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
.
S2CID
224862524
.
- Yam, K. L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009,
ISBN
978-0-470-08704-6
- "What does the cardboard plate in your microwave do?"
.
Coolblue B.V
. Retrieved
6 April
2023
.
- "1981 Corning Microwave Crisper ad"
.
eBay
. Archived from
the original
on 6 April 2023
. Retrieved
6 April
2023
.
External links
[
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]