Science of BBQ | SciByte 6

Science of BBQ | SciByte 6

This week on SciByte …
We take a look at the science of BBQ, taking a with a delightfully scientific look at the science of fire and cooking. Plus, we apply our science filters to the great propane charcoal debate. All that and more, on SciByte!

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Show Notes:


  • Fire is AWESOME.
  • It gave humans the first form of portable light and heat.
  • It gave us the ability to cook food, forge metal tools, form pottery, harden bricks and drive power plants.
  • The ancient Greeks considered the 4 major elements of the universe to be water, earth, air and FIRE
  • Fire is NOT matter
  • Fire IS a visible, effect of matter changing form, part of a chemical reaction
  • The most flammable compounds contain carbon and hydrogen, which recombine with oxygen relatively easily to form carbon dioxide, water and other gases.
  • Color and temperature of a flame are dependent on the type of fuel involved in the combustion, in some blue does indicate the hotter portion of the flame but it’s not a set rule that all blue flame is hotter


  • the process of preparing food by use of heat.
  • Most anthropologists believe that cooking fires first developed around 250,000 years ago.
  • When heat is used in the preparation of food, it can kill or inactivate potentially harmful organisms including bacteria and viruses.
  • Molecular gastronomy is a discipline practiced by both scientists and food professionals that studies the physical and chemical processes that occur while cooking.

Maillard Reaction

  • is not a single reaction, but a complex series of reactions between amino acids and reducing sugars, usually at increased temperatures
  • The reactive carbonyl group of the sugar reacts with amino acid, and forms a complex mixture of poorly-characterized molecules responsible for a range of odors and flavors


  • the browning of sugar
  • Carmelization leads desirable colour and flavour in bakery’s goods, coffee, beverages, beer and peanuts
  • a process used extensively in cooking for the resulting nutty flavor and brown color
  • As the process occurs, volatile chemicals are released, producing the characteristic caramel flavor.

Searing/browning : Does it ‘seal in’ the juices?

  • Browning, also known as the Maillard reaction or caramelization, is caused when you heat sugars and amino acids together.
  • This reaction is what causes that very flavorful and wonderful crusty surface in meat that gives it that great, grilled flavor
    • Sugar based BBQ sauce adds sugars to the surface of the meat that can carmelize

Does it seal in moisture?

  • Experiments that weight similar cuts of meat with/without searing don’t show any weight difference, indicating that it /doesn’t/ seal in juice … but does that simply talk about water? not sure
  • Even science debates this

Muscle Meat gets firmer the more it’s cooked, so you can tell by firmness how it’s cooked.
Analogy :

  • rare/med-rare : fleshy part under your thumb
  • Med : middle of hand
  • Med-well/well done : tight near finger knuckles
    • The protein chains bunch up, and expel excess water. Increasing density.

The Charcoal briquette

  • First invented and patented by Ellsworth B. A. Zwoyer of Pennsylvania in 1897
  • Interest was slow until the 1920’s, when Henry Ford decided to recycle wood scraps from auto making into briquettes

The life Cycle of Today’s Charcoal Briquettes

  • Starts with sawdust and wood chips from lumber mills unloaded and mixed in a pit, the mix travels a conveyor an electromagnet removes any metal contaminates, and a vibrating screen removes larger pieces
  • A long rotating dryer heats it to 1400* for 4 min, it’s sealed from Oxygen to prevent fire
  • Anthracite coal is added, which raises the burning temperature
  • Lime is added, this is what turns the briquet’s white after being lighted
  • Cornstarch is blended in to bind the ingredients together
  • This passes onto a press roll to form the briquette shape, and only takes a fraction of a sec
  • The briquettes are about 35% moisture and soft
  • Go to a 250ft drying tunnel, where they are heated to 280* for 2.5 hours
  • Here the moisture goes from 35%->5% [the lower the moisture level the better the burn]

Carbon + Oxygen + Energy –> CarbonDioxide + Marbon Monoxide

  • C2 + O2 + Energy –> CO2 + CO

Charcoal vs wood

  • Freshly cut wood contains a lot of water — sometimes more than half its weight is water.
  • Watery wood does not make for very efficient cooking.
  • When the tree was alive it contained sap and a wide variety of volatile hydrocarbons in its cells.

Smoke / Volatile Hydrocarbons

  • “Volatile” means that these compounds evaporate when heated.
  • A hydrocarbon is an organic compound consisting entirely of hydrogen and carbon
  • When you put a fresh piece of wood or paper on a hot fire, the smoke you see is those volatile hydrocarbons evaporating from the wood at about 300 F (149 C).
  • If the temperature gets high enough, these compounds burst into flame. Once they start burning, there is no smoke because the hydrocarbons turn into carbon dioxide and water vapor (both invisible).

Charcoal has no volatile hydrocarbons

  • The process of making charcoal drives off all volatile organic compounds
  • This produces a very intense heat with very little smoke, making charcoal very useful as a cooking fuel that will not overwhelm

Flavor / cooking

  • Charcoal does impart some flavor – aroma compounds from the charcoal
  • Lighter Fluid, commonly used to start charcoal cooking, has a stronger flavor.
    • If you want to avoid that taste, could try using a Starter Chimney to start your coals (uses heat convection to ignite the charcoal)
  • Some brands of briquettes include a small amount of starter fluid. If you’re concerned about flavor, keep an eye out for that.

Gas / Propane

  • The majority of gas grills use metal tanks full of liquid propane (LP) gas.
  • LP gas is a fossil fuel, like oil and natural gas.
  • Initially, the natural-gas industry had problems with the “extra” compounds contained in the gas.
  • The propane and butane was unstable, evaporated easily and created higher vapor pressures when storing and transporting natural gas.
  • Dr. Walter Snelling, began experimenting with the condensed forms of these waste materials in 1910.
  • By 1911, he had produced samples of propane and butane and had already envisioned a storage-and-distribution system for these fuels. In 1913, he was granted a patent for his method of producing LP gases

Propane is created from petroleum and contains aliphatic hydrocarbons

  • hydrocarbons composed of nothing but hydrogen and carbon atoms.
  • When you take petroleum and process it in a refinery, you end up with hydrocarbon chains of different lengths.
    • It can be refined from oil and natural gas the same way gasoline is refined from crude oil.
  • These different chain lengths can then be separated from each other and blended to form different fuels.
  • Methane : a single carbon atom & four hydrogen atoms (CH4).
  • Butane : four carbon atoms & ten hydrogen atoms (C4H10).
  • Propane : three carbon atoms chained together & eight hydrogen atoms (C3H8).

Propane + Oxygen → Carbon dioxide + Carbon monoxide + Carbon + Water

  • 2 C3H8 + 7 O2 → 2 CO2 + 2 CO + 2 C + 8 H2O + heat

Propane Starter

  • in a grill starter, the popping noise you hear is a little spring-loaded hammer hitting a crystal and generating thousands of volts across the faces of the crystal.
  • Certain crystalline materials (like quartz, Rochelle salt and some ceramics) have piezoelectric behavior.
  • When you apply pressure to them, you get a charge separation within the crystal and a voltage across the crystal that is sometimes extremely high.
    • inducement of polarization by mechanical deformation of the surface area

Taste Study

  • A taste study was done where people were presented with hamburgers and steak cooked on gas and charcoal.
  • For the hamburgers no one could tell the difference between the charcoal or gas
  • For the steaks however, they could tell the difference,  the charcoal grilled steak had more distinct smoke flavor.
    • There SHOULD be a difference in the taste, right?
    • Propane does produce water as a by-product while charcoal does not

f you heat meat for too long or at too high a temperature, you get burning/charring

  • burning/charring forms carcinogens, benzopyrenes and other undesirable compounds on the surface which are not good for you
  • carcinogen (cancer-causing compound) Heterocyclic amine (HCA),
  • You may increase your stomach cancer changes by 3x if you order your (muscle) meat from med-well to well-done.
  • This applies to anything touching a surface over 400-500*, if you marinate this creates a buffer

Flare-ups happen because fat drips down on charcoal/gas and starts burning

  • If you pre-boil ribs you reduce the fat in them and reduce incidence of flareups!
  • This really means you pre-simmer them just below boiling point, since boiling would rapidly denature -unfold/change structure – the proteins in the connective tissue which could make them tough and chewy
  • This does change the flavor of the meat but …
  • You can pre-flavor the ribs, or even cook them in beer (adds flavor and tenderized the meat)
  • To bring out the most meat flavor required slow cooking, and most people over cook the meat (drying it out too much)

Steaks :

  • Let them set at room temperature (if cold) for 15-20 min, this will allow it to cook more evenly. never more than an hour

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