Heat: Inside Commercial Kitchens

Published on August 13, 2022 | Updated on July 17, 2024 | by Allen Bixby

Welcome to Commercial Cooking @ Home 101. In this chapter we go behind the scenes of a typical restaurant to look at the equipment in the kitchen. We’ll focus on what commercial kitchens and restaurants do so well that we have trouble matching with our traditional home cooking equipment; insanely high heat. Throughout this article you’ll learn how high-performance equipment produces the quick and flavorful results we expect when eating out. By understanding the basics of heat transfer used in a commercial kitchen you can apply basic heat principles restaurants use to imitate them at home.

“Where does he get those wonderful toys?” The Joker (Jack Nicholson), Batman, 1989

On one side of the coin, going into a functioning commercial kitchen it is fun to walk the line (short for cooking line) and look at all that gleaming stainless-steel equipment. Utilitarian and purpose built, for those of us who like to cook it has a well-outfitted workshop feel. The other side of the coin, for those of us who have worked a line and closed the shift, you learn just how much there is to clean.

Different kitchens are, of course, outfitted differently. The huge woks for Asian cuisine, big bay steamers and hot pots for pasta or some seafood joints, the scorching broilers of a good steak house, and of course the flat tops and friers of good old diner foods, and more. Everything tends to be bigger hotter and flashier than our home versions.

If You Can’t Stand the Heat…

Water boiling at 120-degree

We need to look at the science of food, and some of the general physics involved to get a good idea of how this is important. Food in contact with heat is cooking at the most basic. How the heat is applied to the food makes a big difference. That’s our topic here. The idea of seasoning and such, the art part of cooking, is for another day.

How heat transfers, depends in part on the density of the medium making the transfer. For example, walk out into 120-degree air and it feels hot but endurable for some time. Put you hand into 120-degree water and that time is much much shorter. Which is the second aspect of heat transfer important in cooking, the state of the transferring medium; gas, fluid, or solid.

Gaseous heat transfer

Chicken rosting in oven

Gaseous is the scientific way to say air. A broiler has very hot air coming up from the source, and hot solid parts, the rack or grill, that the food rests on. Think about the different look between the parts of the steak that sit on the grill, getting those beautiful grill marks by direct transfer of heat to those areas. Then compare the parts of the steak that do not touch the metal parts, still well colored but typically not as dark.  From that we learn that direct contact with a very dense hot item will have greater affect than hot air. But heated air is still a great part of cooking

An oven has hot air to cook in. One way to accelerate the heat transfer is to keep the air moving so ‘fresh’ hot air is always hitting the food. Now you have a convection oven or an air fryer. That is the basis for how they work. Another way to use heated air is to make it more ‘dense’, typically with water vapor. Anyone who has scalded themselves with steam knows it’s heat transferring power. Cooking a burger on a flat top for instance, burger is almost done, slap some cheese on top, a splash of water near by and put a cover over it, 30 seconds later you have a perfect cheese melt over the patty. Before microwaves, a quick speed steam was a fast, often used, way to catch up any food item that would not get soggy.

Liquid heat transfer

cooking fries in deep pan

The liquid medium creates such thorough contact that it is very effective at getting cooked results. If you have any question about how well the liquid conforms to surfaces so completely, dive in a pool that is colder than you expected. That same thing is what boiling water or heated deep fry oil does to your food. That thorough envelopment allows great direct transfer of heat. Boiling water is limited to 212 degrees, fryers typically stop about 375, depending on the smoke point of your oil, 350 degrees being the most used setting on a fryer.

Both water and oil are used for lower temperature cooking, bringing the immersive power to play for lower and slower. Sous vide cooking has become very mainstream after years as a restaurant process. The device circulates water and keeps it at a precise temperature. Food is bagged or sealed ‘under vacuum’, which is the term sous vide roughly translated. For oil, the common low and slow process is for making confit, usually of meat. This process started out as a food preservation process long before refrigeration. Meat, especially duck, was lightly simmered in its own fats until well cooked, rich in flavor, and inadvertently pasteurized. It was then stored submerged in the fat in clay jars where it could last for months in cool location. There are many methods of cooking with liquid from simmering to braising and more.

Solid surface transfer

Cooking potatoes in skillet

Having access to a larger heated metal surface, a flat top in the restaurant biz, was a ton of fun to play with. Burgers start to finish, breakfast taters, breaded cutlets, grilled sandwiches, caramelized onions…the list is seemingly endless. As it sounds, heat a surface to your desired temp and put the food on it. Now you’re cooking.

You will likely need some kind of oil to avoid sticking of many foods, although breads and many veggies do fine without it. Anything from a skillet to a pan to a sheet of metal over an open fire is transferring heat from a solid surface to your food. It also the basis for all kinds of hybrid approaches using multiple techniques.

Mix and match

Pizza oven and heated skillet

The two best hybrid examples are a pizza oven and a sauteing food. A pizza oven has the surface, usually stone or ceramic that is part of a high heat chamber, as in 600-900 degrees. The pizza hits the surface to instantly crisp up and cook the dough on the bottom. The hot air melts the cheese and gets the toppings hot.

Most sauteed dishes include building a sauce specifically for the dish. Take a scampi dish for example, a heated skillet with oil or butter, add some garlic and the large cleaned prawns, and keep the food moving the hot skillet. Squeeze in some fresh lemon, and dry white wine, cook to your satisfaction. Put the scampi in the dish and pour the pan sauce over it.

The proper way to serve and Italian pasta dish is to boil the noodles and then simmer them in the sauce before serving. Or for lasagna, manicotti, ziti or such, you mostly cook the pasta then add sauce, usually cheese and other goodies then bake in the oven until done.

The next chapter

This is the first installment of articles about the broad concepts and approaches that differentiate commercial cooking from home cooking. The next step is to explore how to get similar results using home equipment and similar tools. We look forward to being part of your journey to better cooking, or maybe you just want to brush up on some aspects of cooking, regardless, thanks for bringing us along.

About the Author Allen Bixby

A retired restaurateur, not quite ready to stop playing in the kitchen.

I have had the pleasure of watching amazing high end chefs, and classic American style diner cooking, creating a very diverse background with food. Add both parents teaching English, watching Julia Childs and Graham Kerr as a child, and learning to bake bread from my Finnish great grandma, and you get a decent recipe for a knowledgeable voice to write about food.

From recipe design to equipment testing, there is a broad spectrum of entertaining aspects of food and how we do what we do every day to feed our loved ones!

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