A bad, musty smell sometimes ruins a bottle of corked wine. Since the 1990s, researchers have known that this unpleasant odor comes from the chemical 2,4,6-trichloroanisole (TCA), which forms when a fungus that infects cork comes in contact with bleach or chlorine products used for sanitation at wineries. Hiroko Takeuchi of Osaka University and her colleagues have now discovered that TCA suppresses the sense of smell, and this causes us to detect a musty odor. The research appears in the Proceedings of the National Academy of Sciences.
A number of naturally occurring compounds, including TCA, ruin the smell and taste of food and beverages. Scientists thought these chemicals activate particular olfactory receptor cells (ORCS), which transmitted bad smells to the brain. However, they were not able to explain how TCA can create its associated odor even at very low concentrations.
To understand the mechanism behind “corked wine smell,” Takeuchi and her colleagues isolated ORCs from newts. When they exposed the ORCs to TCA, they found that rather than stimulating an electric current to flow across the cell membrane, as expected, TCA stopped the flow of current by preventing calcium ions from passing through cyclic nucleotide gated (CNG) channels in the membrane. TCA was much more effective at blocking CNG channels than geraniol, an olfactory masking agent used in perfume, and L-cis-diltiazem, a well known CNG channel blocker.