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The science of
charcoal grilling
More than you ever wanted to know about this
seemingly simple process.
At a fundamental
level, the grill is responsible for containing a charcoal fire and maintaining a distance
from the fire to the food. You hang the food over the fire and the magic starts. But it
happens in a very complex way because of the interaction of flame, smoke, hot air and hot
metal.
There are three fundamental types of heat
transfer going on: radiant heat (hold your hand anywhere around the coals
and feel the heat), convective heat (feel the hot air coming out of the
vents) and conductive heat (the sizzle when a cold steak hits hot
steel).
With most charcoal grills, you build your fire, place the food
and then you start to scramble. Hot spots, cold spots, flare-ups. So without the proper equipment,
you are forced to build three level fires, move the food around, open and close the cover, and try
to time everything perfectly. With this grill you get a measure of
control.
You can control the heat in three major
ways.
- Change the
distance from the food to the fire (radiant
heat)
- Add coals,
or re-arrange the pattern of fire (radiant and
convective)
- Control
airflow to the fire and regulate the air moving past the
food (convective)
- Raise
the charcoal to be sure the grate is hot when the food hits
(conductive)
Radiant Heat and the Lift Arm
As you may recall from high school physics,
radiant heat energy (infra-red) varies as the square of the distance from the source. (Another
of the many inverse square rules first formalized by Sir Isaac Newton.) This means that
as you change the distance from fire to food, the change in heat energy is much faster than the
change in distance.
For example, if you raise the coals from 8
inches below the food to 4 inches below, you would expect to get twice as much heat, but you
actually get four times the radiant heat energy. It's not a linear relationship.
Our B1 grill allows you to vary the heat
roughly 6x from the bottom of the stroke to the top. This is why we say you can give your food
a "blast" of radiant heat to brown, carmelize and generally take advantage of the mysterious
Maillard reactions ...
Oil and
Water
Browning doesn't get going until the
surface of the food reaches at least 250 degrees (F). But your masterpiece can't get any hotter
than 212° until the surface moisture boils off. Nothing good happens until the water evaporates
from the surface and the magic starts. (Most foods that we grill are about 80% water, and, in its
liquid state, water can never get hotter than 212°. This is another reason that charcoal is better
than gas. A gas flame is about 30% water vapor. It simply can't create the same intense, dry heat
as charcoal. Avoid limp vegetables, grey steaks, and steamed ribs. Use a
real fire.)
TIPS:
Dry the surface of your food before you put it on the grill so it can brown quickly. Oil is your
best friend ... almost everything you put on the grill can be dried and oiled before you start.
Also, before you put the food on the grill, get the grate very hot to get extra sear and flavor
where the food contacts the grill. Use rubs instead of sauces. Sauces contain sugar (which
burns) and water (which turns to steam), both of which prevent Maillard reactions that are the
hallmark of fine grilling.
Browning the
food
Food scientists refer to "browning" or
"searing" as Maillard reactions. They are named after Louis Maillard, a physician who, in the early
1900s, described some of the chemistry behind cooking and may have been the first food
scientist.
Dr. Maillard described the affects of high
heat on meat, vegetables, and other foods that are not primarily composed of sugar. (Sugar "simply"
turns to caramel when you heat it. Caramelization is a less complex process that you can
appreciate when you sprinkle a little sugar on a slice of pineapple and caramelize it on the grill
for a few minutes.But back to meat and vegetables...)
Maillard reactions involve carbohydrates and
amino acids reacting in very complex ways when they get hot enough to produce browning,
crispness and intense flavors. The flavors come from pyrazines, oxazoles, and hundreds of other
by-products caused by the heat.
Fire and
Smoke
Once the magic starts, you need to stay in
control. The art of grilling is using high heat to char the surface of your food while controlling
how much heat is absorbed into the center.
(This is why a "Pittsburg" or "Black and Blue" steak is possible. Some of us
like the outside almost incinerated and the inside barely warm. Some of us think that's disgusting.
But nobody likes a tough, grey steak.)
You can't fully
control these variables, but it's really fun to try. This is the art of grilling. The B1
is the grill that will bring out the artist in you.
Suggestions: Raise the coals to make sure you
get browning on the surface, then lower the lever to get the food exactly how you like it cooked in
the center.
Don't be afraid to throw in some wood for a
live flame. Use a thermometer or master the "chef's touch" to see if a steak is done the way you like it. Don't nick the meat with a
knife. All the juice runs out. Master the touch or get a good digital
thermometer.
Coals vs. Hot metal
(charcoal vs. gas)
Hot coals produce much higher radiant heat
energy than you can generate in an oven, gas grill, or ceramic enclosure. In fact, a glowing coal
at around 2,000° F, puts out 40 times as much radiant heat as an equivalent piece of steel at 500°.
(It's the fourth power of the absolute temperatures, if you're interested.) You have to actually
start emitting photons from a material (it starts to glow) before the radiant heat
energy reaches useful levels.
So you can get tremendous heat energy to create
the most excellent food using either charcoal, or white-hot steel.Your choice. Ceramic rocks,
griddles and ovens don't get hot enough.
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