How does a toaster work?

Toasting is a tasty way to increase the durability of bread, and automatic toasters are a convenient way to make toast. Learn more about the chemical change that turns bread into toast and the mechanism behind toasters in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:00):
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(00:29):
Brain with today's question, how does a toaster work? If
you eat bread? Chances are that you have a toaster.
Nearly every household has one. It's a device with amazing
market penetration. Have you ever wondered how your toaster works?
And before answering that question, have you ever wondered why
human beings like toast? What makes toasted bread so popular? Bread,

(00:54):
of course is nice. It's soft, chewy, delicious, a good
way to enjoy we But that softness creates a structural
problem that toast can solve. Dipping a piece of normal
white bread in soup usually results in a saggy mess.
Toast is much stronger, so it can hold up to
soup dipping without difficulty. The other reason for toast has

(01:17):
to do with flavor. When you make toast, you're activating
something called the mayor reaction on the surface of the bread.
This reaction is what causes the browning to occur. The
heat inside the toaster boils off the moisture from the
surface of the bread, and then the surface gets hot
enough for the reaction to take place. It is a

(01:38):
reaction that appeals to the senses we see. The result
of the reaction is browning, sugars and proteins combined together
to create the pleasant flavors and smells that we associate
with toast. A toaster gives us an automatic and convenient
way to activate this reaction whenever we need it. The
convenience is the key to a toaster's appeal. You could,

(02:01):
if you were patient, just hold a slice of bread
over a hot stove burner with a fork to toast it,
but that would be a lot of bother So to
make an automatic toaster, you need four things. First, you
need a source of heat similar to a stove burner. Second,
you need a switch that turns on that source of heat. Third,
you need a timer to turn off the source of heat.

(02:23):
And then you need a mechanism to hold and pop
up the toast. The source of heat is almost always
created by running electricity through something called nichrome wire. Nichrome
wire is an alloy made of nickel and chromium, and
it has two important features. First, when you pass electricity
through this wire, the wire heats up red hot. When

(02:45):
you look inside your toaster and see the glowing red coils,
you are seeing the result of electricity running through nichrome wire. Second,
nichrome wire does not corrode from the heat like many
other metals would. The simplicity and durability of nichrome wire
makes it a common source of heat and everything from
blow dryers to space heaters. If you were to take

(03:08):
a coil of nichrome wire and plug it straight into
a wall socket, it would glow red hot. If you
wrap it around something that can handle heat, like glass
or ceramic, you have the heating element. In a toaster.
A simple vertical tray in a spring can lower the
bread down between the toasters heating elements. When the tray

(03:28):
hits the bottom, it can flip a switch that turns
on the electricity and starts the toasting process. Now, we
need a way to keep the tray down. In most
modern toasters, this involves an electromagnet. The same switch that
activates the heating elements also turns on this electromagnet. It's
magnetic field holds the tray down until the toasting process

(03:52):
is complete. And finally, there's a timer. When you set
the dial on the toaster, that dial controls the amount
of time that the tray stays down. Once time is up,
the timer flips the switch off. This takes the power
away from the heating elements as well as from the electromagnet.
Without the magnetic field to hold the tray down, the

(04:14):
spring pops the tray up and your toast is served.
The next time you make a slice of toast, you
will now know what goes into it. A simple piece
of wire is creating the heat. An electromagnet keeps the
toast in place. A timer turns off both the heat
and the magnetic field, so your toast pops up automatically

(04:35):
with a spring, and it's all happening to activate the
mayor reaction, a reaction that creates taste and smells that
many people enjoy. For more on this and thousands of
other topics. Because it hostof works dot com streaming TV
shows and movies directly to your home is a breeze

(04:57):
with Netflix. As a Netflix Member, you can instantly watch
TV and movies on your PC, mac, mobile device, or
right on your television. Get a free thirty day trial membership.
Go to Netflix dot com slash brain stuff and sign
up today.