Why Does Burnt Toast Smell Linger?
When bread is toasted, the heat causes the sugars and amino acids on the surface to break down and produce a variety of compounds responsible for the toasty aroma. However, if the toast is burnt, these compounds are no longer pleasant-smelling, and instead release acrid, bitter, and smoky odor molecules into the air. These odor molecules are heavier and denser than normal air molecules, so they take longer to disperse. They also cling to surfaces such as walls, furniture, and clothing, making the burnt toast smell linger in the air for much longer.