“Different people have different ways of defining flavor. Our flavor chemists define it as olfactory [or volatile compounds],” says Zata Vickers, a professor in the department of food science and nutrition at the University of Minnesota (St. Paul, Minn.). “Most sensory people define flavor as being a combination of taste plus odor or aroma and the trigeminal sensation.”
Flavors or food aromas are chemical combinations perceived behind the nasal passage by retronasal olfaction through the mouth or nose. Chicken, chocolate and butterscotch all are smells. There are no taste receptors on the tongue for those aromas, says Linda Bartoshuk, a professor in otolaryngology (diseases of the ear, nose and throat) at Yale's (New Haven, Conn.) department of surgery. During chewing and swallowing, the air in the mouth is forced up into the retronasal area, where olfactory receptors signal the brain to identify the smell.