By Karen Kwon
Flavorama
Arielle Johnson
Harvest, $40.00
What gives a lemon its lemoniness? It’s the physical molecules within the fruit. A bite into a lemon wedge sends citric acid molecules and other compounds to the tongue and through the nose, a one-two punch of the sour taste and citrusy scent that the brain senses as lemony.
Being a combination of taste and smell makes flavor a challenge for people who want to master it. There are five distinct tastes — salty, sour, sweet, umami and bitter — and the tongue has dedicated receptors for detecting molecules that correspond to each one (SN: 1/25/16). Smell is more complicated, with about 400 types of smell receptors in the nose that capture signals from many, many different molecules (SN: 3/20/14). Taken together, this means a near-infinite number of flavors exists.