Understanding and managing “heat” is a critical skill required of any good cook, outdoor or indoor. Oddly enough, heat is often poorly understood by many backyard cooks. I can’t provide every fact about heat here – and my knowledge is not complete – so I’ll restrict this post to basic descriptions about the heat used in the most common grilling, barbecuing, smoking and other outdoor cooking situations. Hopefully this post will get the conversation started and you’ll continue it with friends – to expand and improve your knowledge, understanding and mastery of heat.

For our purpose in this post, let’s agree that most often, fire is the source of heat we use in outdoor cooking on grills and in barbecues. Fire requires combustible material, a supply of oxygen and a source of ignition. Be it charcoal in a fire chamber, propane or natural gas in a burner or logs on a camp fire, heat is produced and we can harness that heat to cook foods to our delicious delight. There are numerous combustible materials yet only a few are suitable for cooking food. Learning about fire – source, intensity, duration and temperature – and using this knowledge to manage the heat produced is a basic skill-set of good backyard grilling. But more on that later.

First let’s talk about two terms most often used in association with outdoor cooking – because they describe how ‘heat’ issued to cook the the food.

Direct & Indirect Heat

Direct heat is a term used to describe grilling on the grates directly above the heat source and it is usually hot. Steaks, chops, burgers and fish fillets are usually cooked by this method. Generally when you are cooking food over direct heat you are grilling.

Indirect heat is a term used to describe cooking with the heat source produced in another part of the grill – usually at a lower temperature and the food takes a bit longer to cook. Whole chickens, briskets, roasts and other larger cuts of meat are usually cooked by this method. Generally when you are cooking food using indirect heat you are barbecuing.

Grilling, Barbequing & Smoking – What’s the difference?
Although most Americans generally refer to cooking outdoors on their grill as ‘barbequing,’ technically that isn’t correct – but not a big deal. I’ll provide a brief explanation of the three terms here. [With respect for those folks who have dedicated their waking moments to the pursuit of one or more of these activities; understanding any of them could wax poetically for hours about their pursuit, leaving my humble reasoning in the dust!]

Grilling is fundamentally simply cooking food over a direct heat source – like fire. Generally this is done with smaller cuts of meat at higher temperatures and fast. Smaller cuts of meat sear on the outside from the higher heat, sealing in the juices that would be lost if the meat was cooked slowly. Our distant relatives used this method by placing a chunk of meat on a stick and holding the stick in the fire. There is something in the way the heat affects the meat and crisps the outside surface to create a taste that seems to appeal to the deeply routed DNA of most folks, me included! When you place a grate to suspend the food over the fire or heat source, you are adding the conductive heat of the grates to the cooking process. When you suspend the food over the heat source using a ’spit’ and rotate it to cook evenly, you are rotisserie cooking.

Barbequing is an evolved version of grilling – slowly cooking meat using an indirect source of heat and keeping it at a lower temperature, usually between 225F -250F degrees. If the meat is placed in a position away from the heat, yet ‘bathing’ in the hot air from the heat source, you are barbecuing. If the addition of wood or herbs is made to the fire for the purpose of generating smoke you are beginning to ‘Hot Smoke.” I s’pose you could describe it as “roasting” at a lower and slower temperature – often with cuts of meat that benefit from this type of cooking method. Some cuts like pork shoulders and beef brisket have a high ratio of collagen in the meat, due to their intended use, slow cooking with indirect heat tends to work magic on these cuts and the dense collagen will render into the meat adding tenderness and flavor.

Smoking If you cook on or near an open fire of combustible material like wood, hay, herbs, charcoal or coal – you are going to add flavors of that material to the meat when the chemical reaction of fire releases particles and they impact the food. [Note: In the case of coal - that would not be the best flavor!] If you introduce any of these elements into a cooking situation where they can smolder and generate an excessive amount of smoke, even more flavor particles are added to the air that will come into contact with the food. If you perform this task at a temperature of between 225F – 250F degrees you are essentially “HOT” smoking and the food is slow cooking. Most folks prefer to HOT smoke food in their home equipment so it’s more like a Smokey Barbecue. If the smoke passes through a cooling chamber and comes into contact with the food near or below a temperature of 45F degrees or thereabouts, you are essentially “COLD” smoking and the food isn’t cooking, just being flavored.

Searing & Grilling

Searing is the act of using the direct method of cooking over high heat, upwards of 400F degrees. The higher heat quickly affects the proteins and sugars in the meat causing it to brown and seal. My mother did this before placing a roast in the oven and I do it every time I cook a steak in a cast iron skillet – I sear it. If you are cooking outdoors using a highly conductive metal grate like cast iron, then you may be searing meat using a combination of direct heat from the fire as well as the conductive heat from the metal grates.

Grilling is as described above, and it is also an overall term describing a cooking ‘technique.’ In most “grilling” situations the cook first sears the meat on a very hot area of the grill and then continues to cook it with lower intensity direct heat on another part of the grill, using the convection heat of the hot air produced by the heat source, the conductive heat of the grates and (possibly) radiant heat from either charcoal or infrared burners.

[NOTE: Please read the comments about Searing and Grilling below. There is some useful information provided by readers and the conversation may help you come up with what works best for you. - CB]

Low & Slow

Talk to any long-time outdoor cooking enthusiast and you will hear this phrase as if it were the official motto of all barbecue. “Low” refers to the temperature, generally between 225F – 250F degrees. “Slow” refers to the time it takes. Simply stated, ‘Good Eats come to those who cook ‘Low and Slow.’ When you are cooking “Low & Slow” you are usually barbecuing or smoking.

Now let’s talk about the three basic categories of heat you will use in cooking outdoors:

Convective, Conductive and Radiant

Convective Heat is best explained by example. Hot air is convective heat. The air is warmed by a source and carries the heat (with some loss during the transfer) to the food to be heated. Most common indoor ovens are convective – and manufacturers will add a fan to circulate the air and call it a ‘convection oven’ when, in fact it already is. A grill with the hood closed is a convection oven. A barbecue is a convection oven. A smoker is a convection oven. They all use heated air to transfer heat to the food. That’s why during long barbecue and smoking processes the cooks will use a mop to add moisture to the outside of the meat – or add a tray of water to help control the hot air to keep it from drying out the food. Oh – and now for the head-spinner for some of you: Frying is Convective. The hot oil is heated and transfers the heat to the meat.

Conductive Heat is also best explained by example. Placing food in a pan on a burner is using conductive heat transferred from the burner through the metal pan and directly in contact with the food. In a previous description I said that metal grates over a heat source can also be conductive – because they collect heat and transfer it directly to the food. When food cooked on the grates gets grill marks it’s because of conductive heat at higher temperatures.

Radiant Heat For the purpose of this post I’m only going to describe Radiant Heat as it pertains to outdoor cooking and the use of ‘infrared’ energy. Infrared energy is emitted from any number of sources in our lives – the most influential being the Sun. If you use a mirror to collect and reflect sunlight onto a piece of meat, you are using infrared energy to cook it. Infrared is easily demonstrated (but not fully explained) by describing how the sun feels on your arm when you place it in direct line of the sunlight on a cold day, with something to block the wind that minimizes the sensations, for instance in the window of your home or car. The sun warms the skin because the infrared energy emitted by the sun activates your skin on contact. Charcoal fires have been used in cooking for centuries, before being contained in a backyard grilling chamber, but I bet most folks who use them and comment on the great taste of charcoal fires, don’t know it’s that charcoal fires also emit infrared energy – but only a small amount due to inefficiency – and that’s what actually contributes to the taste of the meat. Any outdoor campfire will produce a percentage of infrared, that’s the feeling on your face when it’s cold outside but the light from the embers of the fire hits your skin and it warms – it’s actually light energy and infrared energy. The more fuel being burned, the greater the amount of infrared energy being generated – but not necessarily an efficient production – and thus the intensity of heat on your skin. Infrared energy is a great way to cook on a grill because it can generate high temperatures and provides all of the convenience of gas with the taste of charcoal.

Charcoal, Gas or Infrared?
These are the three main fuel sources for most outdoor cookers. There are a few others, but for the everyday backyard cook these are the primary choices. Interestingly when using one of these three terms to describe your cooking technique, it also provides a hint as to the amount of heat the cooker will be generating.

Charcoal
Charcoal generated heat is often referred to as “live fire.” Igniting and managing the charcoal fire is a skill-set learned by experience. Charcoal tends to burn hotter than gas cookers and may also provide additional flavor from the smoke byproduct. Charcoal also emits a low level of infrared energy. Charcoal comes in two primary forms that are marketed in general retail stores: ‘briquettes’ & ‘hardwood or lump.’ Briquettes are more common and can be purchased in various size bags at just about any store in the summer months, and year-round in most grocery stores. Briquettes are manufactured using real charcoal and binder materials (which may include flavor or smoke enhancing ingredients like wood) and are formed into sizes which are easy to store, ignite and manage. Some ‘briquettes’ have additional ingredients which accelerate the briquette catching on fire. Hardwood or lump charcoal was originally used by most outdoor cooks and is actual hardwood that has been partially burned, effectively removing the sugars and other flammable materials – leaving behind only the material that makes great embers – perfect for producing cooking heat. If you burned a pile of wood down to the glowing chunks of embers and then instantly starved the fire of oxygen, you’d pretty much have charcoal. Charcoal grills are generally excellent for hot and fast grilling of steaks and chops, while charcoal fires can also be managed to deliver low & slow heat for barbecuing and smoking food.

Gas
Gas is available as liquid propane in various size containers, ranging from small and portable to the large and permanent. Natural gas is available from utility companies and is generally available only through pipelines in municipalities. Essentially both have the same properties when it comes to outdoor cooking with only slight variances in performance. Gas provides the outdoor cooking enthusiast a convenient and clean form of fuel that is easy to control volume and thus the intensity of the heat. Most gas cookers do not generate the intensity of heat that charcoal fires will – and are primarily useful for direct grilling using convection.

Infrared
Infrared energy is produced naturally by the sun and by fire. Some electrical lamps produce infrared energy. Infrared energy does not require air (convection) to transfer energy nor does it require grates (conduction) to sear food. Infrared energy impacts the food and reacts at that precise moment, generating heat and with more infrared energy the meat or other food is seared by the energy, locking in moisture and it continues to cook as more infrared energy penetrates and affects the proteins and natural sugars in the food. While all charcoal fires generate infrared energy, it is highly inefficient and nearly unmanageable as well as low level.

More than 15 years ago TEC introduced the first outdoor grills using infrared energy to sear food on outdoor grills. Char-Broil introduced the first affordable infrared grills in 2007 using a newly patented TEC searing burner. In 2007 Char-Broil also introduced The Big Easy, an oil-less infrared turkey fryer. In 2008 Char-Broil is introducing several new infrared systems including Quantum and RED.

Heat is good – and basic to good grilling.

Does this help you with your understanding of heat? See something you want more information about or do you disagree with something I’ve written? Let me know by posting your comments and questions below!

Happy Grilling!