Conduction, Convection and Radiation

Conduction

Conduction is the process of heat transfer through a solid material.
It happens when the molecules of a substance transfer the heat energy to the neighbouring molecules.
In food preparation, this is observed when a pan is heated from the bottom. The heat from the stove moves through the pan’s metal to the food.
This specifically applies to the process of grilling, frying, and boiling where the cooking vessel transfers heat to the food.

Convection is the heat transfer in gas or liquid by the circulation of currents from one region to another.
It happens when the hotter part of a mass of air or water rises and the cooler parts descend.
In cooking, this process is applied when you are boiling water for pasta, or in the oven where the hot air circulates and cooks the food.
Most modern ovens come with a fan-assisted function to increase the convection process and distribute heat evenly.

Radiation is the process where heat energy is transferred in the form of electromagnetic waves.
It requires no medium and can occur in a vacuum.
Radiation can be observed during grilling, toasting, and microwave cooking.
For instance, during grilling, the food absorbs the heat directly from the glowing heat elements.
Microwaves are a form of thermal radiation, which uses radio waves to directly affect the molecules in food, causing them to move and produce heat.

Understanding these heat transfers is crucial as they have different impacts on food and its final outcome.
Conduction is direct heat and can make the food crispy whereas convection evenly cooks the food through continuous circulation.
Radiation accomplishes a more uniform internal temperature for the food.
Using the right method of heat transfer helps to control the cook, preserve nutrient content and enhance the overall quality and sensory attributes of the food.