Heat Transfer Food Science What is heat transfer

Heat Transfer Food Science

What is heat transfer? n n The transfer of energy from a heat source to food. Heat always travels from a hot area to a cool area.

Heat is transferred during cooking in one of three ways: n Conduction n Convection n Radiation

Conduction: *Occurs when molecules collide with one another *Since heat always moves from hot to cold areas, the more heat there is, the faster the collisions will be.

For Example: n If a cool pan touches a hot stove burner, the molecules in the hot burner will collide with the cool pan, thus causing kinetic energy.

Kinetic Energy n n The energy of motion. The molecules on the outside of the pan collide with the molecules deeper within the pan. The process continues until it reaches the cold food in the pan. Then, the molecules in the hot pan collide with the cold molecules in the food, transferring heat to the food.

See diagram below:

Heat Transfer n Convection

Convection n The transfer of heat by the motion of fluids such as water or air.

How convection works: n n n A. As a fluid is heated the molecules are pushed further apart, causing the fluid to become less dense. B. The hot particles rise, causing the cooler particles to become more densely packed. They sink and come into contact with the heat source. C. The process continues until all the fluid is the same temperature.

See diagram below: n

Baking and Roasting n Baking is the technique of prolonged cooking of food by dry heat acting by convection, and not by radiation, normally in an oven, but also in hot ashes, or on hot stones. (Wikipedia- Oxford English Dictionary)

Baking Tips: n n n Most dishes should be placed in the center of the oven, so that it will cook evenly. The heat needs to be able to circle the pan. Do not place too many pans in the oven so that they touch the sides of the oven wall, thus blocking hot air circulation around the pans.