These are the chemical reactions that make barbecue so delicious

These are the chemical reactions that make barbecue so delicious thumbnail
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This article was originally featured on The Conversation.

Just the thought of barbecue’s delicious aromas and intoxicating flavors will make most people’s mouths water. It’s barbecue season in the U.S .

I am a chemist that studies compounds found in nature ,. I also love food, including barbecue. Although it may seem easy to cook on a grill, there are many chemistry factors that make barbecue different from other cooking methods. This makes it a wonderful experience.

Cooking With Fire

First, it is important that you define barbecue. The term can refer to different things in different countries or cultures. Barbecue is simply the cooking of food over an open fire. The heat that heats the food is what sets barbecue apart from other cooking methods.

On a barbecue, the hot grill grates heat the food via direct contact through a process known as conduction. The food also warms and cooks by absorbing radiation directly from the flames below. You can sear the meats that touch the grill and cook the rest of the food on the griddle using a combination of heating methods. The result is a complex mix of flavors and aromas due to the wide range of temperatures. Cooking on a stovetop produces less radiation, and the majority of the cooking takes place where the food is directly in contact with the pan.

When barbecuing, the food can be placed directly above the flames (called direct Heat -) or further away using indirect heat. The direct cooking method subjects the food to very high temperatures, as the grilling surface can be anywhere from 500 to 700 degrees Fahrenheit (260 to 371 Celsius). The indirect cooking method places the heat source to the side of the food or far below, exposing the food to temperatures around 200 to 300 F (93 to 149 C).

Cooking refers to the use of high temperature to cause chemical reactions which alter food at a molecular level. The first thing that happens when you cook meat at higher temperatures, such as on a barbecue, is that the water near the meat’s surfaces boils off. Once the surface is dry, the heat causes the proteins and sugars on the outside of the meat to undergo a reaction called the Maillard Reaction. This reaction creates a complex mixture molecules that makes food more savory or “meaty”. It also adds depth to flavors and aromas. Many variables influence the flavor and reaction, including temperature, acidity, and ingredients in sauces, rubs, and marinades.

Similar processes occur with vegetables. Barbecuing allows water to evaporate or drip down from the vegetables without being trapped in a pan. This keeps the vegetables from becoming soggy and promotes caramelization reactions. These reactions turn carbohydrates and sugars into smaller compounds like maltol-which has a toasty flavor-and furan-which tastes nutty, meaty and caramel-like.

Char and crisp

Another hallmark of barbecued food, is the unique char that it develops. The non-carbon atoms of food that are exposed to heat for long periods of time can break down leaving behind crispy, black carbon. This is the process of burning or charring.

While it is rare to enjoy a fully cooked piece of meat, a little bit of crispy char flavor can make foods more delicious. You can adjust the amount of char you want by cooking over direct heat.

Unfortunately for those who like a little extra crisp, some of the chemicals in charred meat-molecules called heterocyclic amines and polycyclic aromatic hydrocarbons-are known carcinogens. Though the dangers are far lower than smoking cigarettes, for example, limiting the amount of charring on meats can help reduce the risk of developing cancer.

Smokey flavors

Smokiness is the final and most important flavor of barbecue. Smoke is a major ingredient when cooking over charcoal or wood. Even on a gas barbecue, melting fats can drip onto the heat source and create smoke. The barbecue will absorb the flavors of the food as smoke swirls around it.

Smoke consists of gases, water vapour and small solid particles. Burning wood breaks down molecules called lignans, and these turn into smaller organic molecules – including syringol and guaiacol-that are mainly responsible for the quintessential smokey flavor.

When smoke comes in contact with food, the components of the smoke can get absorbed. Because food contains both fats as well as water, it is especially good at taking on smokey flavors. Each type of molecule can be bound to the other. Fats are non-polar in chemistry. This means they have a weak electrical charge and can easily grab other nonpolar molecules. Water is polar, meaning it has both a positive and a negative charge. It is also good at binding to other non-polar molecules. Different foods absorb smokey flavors differently, depending on the composition. You can make food smokeier by using chemistry during barbecuing.

Smoke can contain hundreds of possible carcinogens depending on what you are burning. Only a small amount of research has been done on whether grilled foods absorb enough smoke to pose a significant risk to health. But researchers know that inhaling smoke is strongly correlated with cancer.

While barbecuing your favorite meal may seem like a simple pleasure, the science behind it can be quite complicated. You will be able to appreciate the variety of compounds and reactions that led to the delicious smoky flavor of barbecued food the next time you try it.

Kristine Naolin is Associate Professor of Chemistry at University of Richmond .

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