What Is Infrared?
In the simplest terms, infrared energy
is light that we cannot see, but our bodies can detect as heat. It is
part of the electromagnetic spectrum that includes radio waves, X-rays
and visible light. All of these forms of energy have a specific
frequency, as represented in the chart below.
Infrared energy is comprised of those
frequencies that exist just below the red end of the visible spectrum,
and for cooking properties they have a very unique benefit - when they
strike organic molecules (such as any type of food), they cause the
molecules to vibrate, thereby creating heat. Although almost any type of
electromagnetic energy can cause heating, for the purpose of cooking,
infrared energy is the perfect choice.
RADIANCE VS. CONVECTION
Without getting overly technical, heat transfer can occur one of three
ways - conduction, convection or radiation. Conduction requires direct
contact between two objects and is used frequently in cooking. Sauteing
and pan-frying both rely on conduction to work. Convection relies on
heat transfer via a liquid or gas. The heated molecules of air or water
physically bump into other molecules, and transfer some of their energy.
This process is also regularly used in cooking, whether you are boiling,
deep frying or cooking on a conventional gas grill.
Radiant heating is different. It does
not rely on any intermediary to conduct heat - it works directly on the
molecules in its path. Because of this, it is highly efficient. Any heat
transfer involves some loss, so when you have a gas flame, heating air,
then heating a radiant, then heating air some more, then finally heating
your food (as in a traditional grill), you have much more loss than if
that heat energy goes directly from the source to the food being cooked.
SEEING IS BELIEVING
Below is a photo of the firebox of a Solaire InfraVection grill, taken
with a normal camera and with a camera that can detect infrared energy.
On the left side is the ceramic infrared burner; on the right is the
traditional convection burner.
There are two important things to
notice in the infrared image. First, the IR burner looks much brighter
in infrared. This is because the camera is taking the infrared energy
and converting it to visible light. Second, notice that the steel
vaporizer plate over the convection burner looks brighter in the
infrared image also. This is because all hot objects emit some infrared
light. As is obvious from the photo, though, some objects emit better
than others.
WHY INFRARED IS BETTER FOR GRILLING
When we grill, we are replicating the oldest cooking method known - the
open fire. In a natural fire, whatever the fuel being used (wood,
charcoal, etc.) there is a tremendous amount of infrared energy being
produced. This is easily verified by color. A wood fire burns
yellow-orange. Coals glow a dull red. Physics tells us that any heat
source will emit light at a wavelength nearest the wavelength of the
dominant energy production, so, in simple terms, the redder it gets, the
more IR it's producing. A blue gas flame can't replicate the open fire
experience because it simply produces the wrong "color" of
heat.
Another significant benefit of infrared
grills is in moisture retention. As we discussed earlier, convection
heats by first heating air, then pushing that hot air onto the food.
Think for a minute what a hot wind does to your skin. It dries it out. A
convection grill is doing the same thing to your food. All that rising
hot air carries away a little bit of moisture each time it blows by.
Infrared energy has an opposite effect, actually driving moisture away
from the surface and deep into the item being grilled. This process
enhances flavor and creates a succulence that is difficult to replicate
with other cooking methods.
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