Self-heating food packaging

Short description: Food packaging that uses exothermic reactions to heat its contents

A Unitized Group Ration – Express self-heating field ration being heated in its box

Self-heating food packaging is active packaging with the ability to heat food contents without external heat sources or power, usually using an exothermic chemical reaction. Packets can also be self-cooling. These packages are useful for military operations, during natural disasters, or whenever conventional cooking is not available. They are often used for military field rations, camping food, instant food, or other types of food intended for preparation where proper cooking facilities or methods are unavailable or less ideal.

## Contents

* 1 Chemistry
* 2 Design
* 3 History
* 4 See also
* 5 References
* 6 Further reading
* 7 External links

## Chemistry

Self-heating rice with quicklime and water as heating source, taken before adding water to quicklime

The source of the heat for the self-heated can is an exothermic reaction that the user initiates by pressing on the bottom of the can. The can is manufactured as a triple-walled container. A container for the beverage is surrounded by a container of the heating agent separated from a container of water by a thin breakable membrane. When the user pushes on the bottom of the can, a rod pierces the membrane, allowing the water and heating agent to mix. The resulting reaction releases heat and thus warms the beverage which it is surrounding.[1]

The heating agent and responsible reaction vary from product to product. Calcium oxide is used in the following reaction:

CaO(s)+ H2O(l) → Ca(OH)2(s)

Copper sulfate and powdered zinc can also be used, but this process is less efficient:

CuSO4(s) + Zn(s) → ZnSO4(s) + Cu(s)

Anhydrous calcium chloride is often used as well. In this case, no chemical reaction occurs, instead the heat of solution is generated.

Commercial heat sources for self-heating food packaging use an exothermic (heat releasing) reaction, for which there are several common formulations. These include:

* Quicklime aka calcium oxide, and water. Quicklime, inexpensive and readily available, is generally recognized by the FDA as safe.[2] The product of the reaction is calcium hydroxide.
* Finely powdered magnesium metal alloyed with a small amount of iron, and table salt, actuated by adding water, as in an MRE flameless ration heater.

Some newer formulations use a Thermite-like reaction between a more reactive metal powder such as aluminum or magnesium, with a less reactive metal oxide such as iron oxide or silicon dioxide.[3]

During World War II Heinz took a different approach, using a mechanism developed by Imperial Chemical Industries which involved igniting a smokeless fuel in the can.[4]

## Design

Self-heating cans have dual chambers, one surrounding the other. In one version, the inner chamber holds the food or drink, and the outer chamber houses chemicals which undergo an exothermic reaction when combined. When the user wants to heat the contents of the can, a ring on the can—when pulled—breaks the barrier which keeps the chemicals in the outer chamber apart from the water. In another type, the chemicals are in the inner chamber and the beverage surrounds it in the outer chamber. To heat the contents of the can, the user pushes on the bottom of the can to break the barrier separating the chemical from the water. This design has the advantages of being more efficient (less heat is lost to the surrounding air) as well as reducing excessive heating of the product's exterior, causing possible discomfort to the user. In either case, after the heat from the reaction has been absorbed by the food, the user can enjoy a hot meal or drink.

## History

WW2 era Heinz/ICI self heating soup can

Designs for self-heating food packaging date back to at least 1907.[4]

During World War II, Britain introduced them to troops rations for the Normandy landings using the ICI smokeless fuel mechanism.[4] This mechanism was not fool-proof and the cans could sometimes explode.[4] Cans using this mechanism continued to see some use after World War II with some making their way to the Falkland Islands Dependencies Survey.[4]

## See also

* Beverage can
* Flameless ration heater

## References

1. ↑ & Berntsen, James L."Container with integral module for heating or cooling the contents" US patent 5461867, published 1995-10-31, issued 1998-11-11, assigned to Insta-Heat, Inc.
2. ↑ "ITG Subject: New Source of Lead and Other Contamination" (in en). 12 August 2007. http://www.fda.gov/ora/inspect_ref/itg/itg17.html.
3. ↑ Lorch, Mark (19 June 2018). "Self-heating drinks cans return – here's how they work" (in en). http://theconversation.com/self-heating-drinks-cans-return-heres-how-they-work-98476.
4. ↑ 4.0 4.1 4.2 4.3 4.4 Rozeik, Christina (10 November 2015). "Object in focus: self-heating cocoa tin". Scott Polar Research Institute. Archived from the original on 19 July 2025. https://web.archive.org/web/20250719064706/https://www.spri.cam.ac.uk/museum/news/object-in-focus/2015/11/10/object-in-focus-self-heating-cocoa-tin/.

## Further reading

* Yam, K.L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009, ISBN 978-0-470-08704-6

## External links

* Single-serving coffee can heats itself
* Will Self-Heating Coffee Be Cool?
* BBC News Online - Hot drink can tested in Midlands
* An article with photos on disassembly

* v
* t
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Packaging

General topics|

* Active packaging
* Child-resistant packaging
* Contract packager
* Modified atmosphere/modified humidity packaging
* Package pilferage
* Package testing
* Packaging engineering
* Resealable packaging
* Reusable packaging
* Reuse of bottles
* Shelf life
* Shelf-ready packaging
* Shelf-stable
* Sustainable packaging
* Tamper-evident
* Tamper resistance
* Wrap rage

Product packages|

* Alternative wine closure
* Beer bottle
* Box wine
* Case-ready meat
* Coffee bag
* Cosmetic packaging
* Currency packaging
* Disposable food packaging
* Drink can
* Egg carton
* Evidence packaging
* Flour sack
* Foam food container
* Food packaging
* Glass milk bottle
* Growler
* Juicebox
* Luxury packaging
* Milk bag
* Optical disc packaging
* Popcorn bag
* Pharmaceutical packaging
* Plastic milk container
* Self-heating food packaging
* Screw cap (wine)
* Single-serve coffee container
* Water bottle
* Wine bottle

Containers|

* Aerosol spray
* Aluminium bottle
* Aluminum can
* Ampoule
* Antistatic bag
* Bag-in-box
* Bag
* Barrel
* Biodegradable bag
* Blister pack
* Boil-in-bag
* Bottle
* Box
* Bulk box
* Cage
* Case
* Carboy
* Carton
* Chub
* Clamshell
* Corrugated box design
* Crate
* Disposable cup
* Drum
* Endcap
* Envelope
* Flexible intermediate bulk container
* Folding carton
* Glass bottle
* Gunny sack
* Inhaler
* Insulated shipping container
* Intermediate bulk container
* Jar
* Jerrycan
* Jug
* Keg
* Mesh bag
* Multi-pack
* Oyster pail
* Packet (container)
* Padded envelope
* Pail
* Paper bag
* Paper sack
* Plastic bag
* Plastic bottle
* Retort pouch
* Sachet
* Security bag
* Self-heating can
* Shipping container
* Skin pack
* Spray bottle
* Stand-up pouch
* Steel and tin cans
* Tetra Brik
* Thermal bag
* Tub (container)
* Tube
* Unit load
* Vial
* Wooden box

Materials and
components|

* Adhesive
* Aluminium foil
* Bail handle
* Bioplastic
* Biodegradable plastic
* BoPET
* Bubble wrap
* Bung
* Cellophane
* Closure
* Coated paper
* Coating
* Coextrusion
* Corrugated fiberboard
* Corrugated plastic
* Cushioning
* Desiccant
* Double seam
* Foam peanut
* Gel pack
* Glass
* Hot-melt adhesive
* Kraft paper
* Label
* Lid
* Linear low-density polyethylene
* Liquid packaging board
* Low-density polyethylene
* Metallised film
* Modified atmosphere
* Molded pulp
* Nonwoven fabric
* Overwrap
* Oxygen scavenger
* Package handle
* Packaging gas
* Pallet
* Paper
* Paper pallet
* Paperboard
* Plastic film
* Plastic pallet
* Plastic wrap
* Polyester
* Polyethylene
* Polypropylene
* Pressure-sensitive tape
* Pump dispenser
* Screw cap
* Screw cap (wine)
* Security printing
* Security tape
* Shock detector
* Shock and vibration data logger
* Shrink wrap
* Slip sheet
* Staple (fastener)
* Strapping
* Stretch wrap
* Susceptor
* Tamper-evident band
* Tear tape
* Temperature data logger
* Time temperature indicator
* Tinplate
* Velostat

Processes|

* Aseptic processing
* Authentication
* Automatic identification and data capture
* Blow fill seal
* Blow molding
* Calendering
* Canning
* Coating
* Containerization
* Corona treatment
* Curtain coating
* Die cutting
* Die forming (plastics)
* Electronic article surveillance
* Extrusion
* Extrusion coating
* Flame treatment
* Glass production
* Graphic design
* HACCP
* Hermetic seal
* Induction sealing
* Injection moulding
* Lamination
* Laser cutting
* Molding
* Package tracking
* Papermaking
* Plastic welding
* Plastics extrusion
* Printing
* Quality assurance
* Radio-frequency identification
* Roll slitting
* Shearing (manufacturing)
* Thermoforming
* Track and trace
* Vacuum forming
* Ultrasonic welding
* Vacuum packaging
* Verification and validation

Machinery|

* Barcode printer
* Barcode reader
* Bottling line
* Calender
* Can seamer
* Cartoning machine
* Case sealer
* Check weigher
* Conveyor system
* Extended core stretch wrapper
* Filler
* Heat gun
* Heat sealer
* Industrial robot
* Injection molding machine
* Label printer applicator
* Lineshaft roller conveyor
* Logistics automation
* Material-handling equipment
* Mechanical brake stretch wrapper
* Multihead weigher
* Orbital stretch wrapper
* Packaging machinery
* Palletizer
* Rotary wheel blow molding systems
* Shrink tunnel
* Staple gun
* Tape dispenser
* Turntable stretch wrapper
* Vertical form fill sealing machine

Environment,
post-use|

* Biodegradation
* Environmental engineering
* Glass recycling
* Industrial ecology
* Life-cycle assessment
* Litter
* Packaging waste
* Paper recycling
* Plastic recycling
* Recycling
* Reusable packaging
* Reverse logistics
* Source reduction
* Sustainable packaging
* Waste management

Category: Packaging

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