What is Thermal Cooking and How Does It Work?

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This graphic is used with kind permission from Sinnport

The modern thermal cooker uses the concept of the hay box where by placing hay or straw around a cooking pot of heated food the meal continues to cook without fuel.

In the mid 1990s the thermal cooker developed in Asia. It consisted of two pots, one within the other. The inner pot made from stainless steel was used to bring the food up to the boil and the outer, twin walled with a vacuum between the walls, was used as the container to keep the cooking process continuing.

These cookers had a particular appeal to Cantonese cooks from Guangdong in Southern China where many dishes require prolonged braising or simmering.

To use the thermal cooker the food is put into the inner pot and brought to the boil, simmered for about 10 minutes and then placed in the outer pot for continued cooking.

There are a number of thermal cookers on the market. Some use insulation material between the outer pot walls, others, like the Mr D’s Thermal Cooker use a vacuum.

Thermal cookers with two inner pots (one above the other) allow you to cook two items at the same time, such as curry and rice. All thermal cookers are capable of cooking many dishes from soups to puddings. Cakes and bread can also be cooked by partly submerging the cake/bread tin in boiling water.

The main benefits of thermal cooking

  • You only need to spend a short time preparing the food in the morning to have a hot meal later in the day
  • You save up to 80% in fuel costs
  • There is hardly any smell of cooking when using a thermal cooker
  • The food can never be overcooked
  • All the vitamins, nutrients and flavours are kept in the pot
  • You can adapt most slow cooker recipes to work with the thermal cooker
  • The cooker can be taken with you and will continue cooking without power. Ideal to transport cooking food in a car, a caravan, a boat or a motor home. You can even take it with you camping.

How does it work? – Simply place your prepared ingredients in the inner pot and heat on a stove.
After it comes to the boil, reduce heat, cover and simmer for 10-15 minutes.
Turn off heat and transfer the inner cooking pot, with the lid on, into the insulated outer container and shut the lid. That’s it.
The heat is retained and your meal will continue slowly cooking for hours until you are ready to eat.

How hot will it keep food? – Due to excellent insulation, there is only a heat loss of 3-4 degrees C per hour.
This leads to the same effect as gently and slowly cooking your food for hours, but without constant attention.
After 6 hours, food in the Shuttle Chef  will still have a temperature around 70 C. providing the inner pot is 75 to 80% full. 

Points to remember when cooking thermally

1. The system only works effectively if there is adequate heat developed within the cooking pots and food to be cooked.

2. To last the longest period and still be above food safety temperature the inner cooking pot needs to be 75 to 80% full and to have been at simmering temperature for the required period (this is to ensure that everything within that inner pot, including the pot, has reached the highest temperature)

3. Do not freeze the inner cooking pot as it’s constructed of a special sandwiched ply base with dis-similar metals for maximum heat and cold retention and they will expand and contract at differing rates. However you can certainly chill the inner pot in a refrigerator.

4. You can keep foods, such as butter, cheese & cold meats, chilled for an extended period by placing ice cubes (in a sealed plastic bag) in the bottom of the inner pot with the food on top.