Why can you smell the aroma of barbecue in your yard?

The aroma of barbecue in the backyard can be attributed to the diffusion and release of volatile compounds resulting from the cooking process. When foods are heated or charred over a grill or barbecue, various chemical reactions occur, including the Maillard reaction, caramelization, and pyrolysis, which produce a range of aromatic compounds known as volatile organic compounds (VOCs).

Maillard Reaction: This reaction is a non-enzymatic browning reaction that occurs between amino acids and reducing sugars when heated. It produces a variety of flavorful and aromatic compounds, including pyrazines, furans, and melanoidins. These compounds are responsible for the characteristic flavors and scents associated with grilled or roasted foods.

Caramelization: When natural sugars in foods, such as those found in marinades, sauces, or the foods themselves, are exposed to high temperatures, they undergo caramelization. This process involves the breakdown and rearrangement of sugar molecules, resulting in a sweet, toasty aroma and flavor, as well as the characteristic brown or golden color associated with barbecued dishes.

Pyrolysis: At higher cooking temperatures, especially when there is direct and intense heat involved, pyrolysis occurs. This process entails the chemical decomposition of organic materials due to the high temperatures. During pyrolysis, complex molecules break down, forming simpler compounds, which often yield smoky and sometimes acrid aromas.

The combination of these chemical reactions and the release of VOCs result in the diffusion of aromatic compounds into the surrounding air. These molecules are carried by air currents and can be detected by our olfactory receptors, allowing us to perceive the distinct and pleasant smell of barbecue in our backyard or the local neighborhood.