A toaster is a machine for toasting food such as sliced bread and bagels. Toasted bread is called toast.
A typical toaster works by heating the bread. The heat is usually produced by conducting electricity through nichrome wires (Joule-effect). The toasting process consists of reducing the bread's water content (originally ~35% of total weight), raising its temperature, and slightly charring its surface.
A typical modern 2-slice toaster uses about 900W(?) power and makes toast in 1-3 minutes.
Rough calculations for the energy required to toast a slice of bread:
A slice of bread weighs about 32g and has about 35% water. The ambient temperature is 25°C.
The specific heat for dry bread is about the same as water, which is 1 cal/g°C.
Reducing the average water content to 10% by heating the bread to 100°C --> 28kJ
Energy to char the surface is assumed to be insignificant.
General Electric released an electric toaster in 1909, patented under the name D-12. It is widely thought to be the first electric toaster on the market, but there is some controversy. An ad for the Pacific Electric Heating Company's competing Hotpoint brand toaster ran in the Saturday Evening Post in 1917, claiming,
The First Electrical Bread Toaster a "Hotpoint."
Perhaps you didn't know that the very first toaster made was a Hotpoint. That was 12 years ago. http://www.toaster.org/hotpoint.html
That ad places the Hotpoint's introduction in 1905, the very year Albert Marsh developed Nichrome wire. Nichrome could endure a suitable heat for a long time, and the discovery of such a filament had been the lynchpin of electric toaster development.
The pop-up toaster, which ejects the toast after toasting it, was patented by Charles Strite in 1919.
In 1925, using a redesigned version of Strite's toaster, the Toastmaster Company began to market the first household toaster that could brown bread on both sides simultaneously, set the heating element on a timer, and eject the toast when finished. By 1926, Charles Strite's Toastmaster was available to the public and was a huge success.
More recent additions to toaster technology include the ability to toast frozen bread, separate operation levers to allow users to toast either two or four slices, and reheating functions which allow toast to be warmed without being burned.
"Toaster Ovens" perform toasting functions of a pop-up toaster, however, the electric filaments are positioned horizontally. A toaster oven usually has a glass door and a pull out tray upon which the object to be toasted is placed. Because of its design, a toaster oven can also perform some of the functions provided by a regular oven, but on a somewhat smaller scale.
