Mint, collectively the genus of plants belonging to the Mentha genus, has around 13-18 distinct species in addition to a number of hybrids of cultivars. The leaves of this herb are harvested for use in food and drinks to add an aromatic and sweet flavor with a cool aftertaste, and can also be used as a natural medicine for easing digestive irritation and nausea.
Two of the most common and popular mints are peppermint and spearmint, both of which have a somewhat similar aroma and taste but are distinct enough that you probably wouldn’t want to substitute one for the other. So how are they different?
Spearmint, Mentha spicata, contains an abundance of L-carvone, one of the enantiomers of the carvone molecule, that lends a sweet and minty smell. The essential oil of spearmint is composed of 50-80% L-carvone and also contains limonene (found in citrus peels), dihydrocarvone, and 1,8-cineol (eucalyptol), but minimal amounts (<1%) of menthol and menthone.
Peppermint, Mentha x piperita, is a hybrid between spearmint and watermint. Peppermint oil is noted for its high menthol content, as well as menthone and menthyl acetate, contributing to the aroma and cooling sensation. Menthol causes this cooling sensation by chemically triggering the cold-sensitive receptors in the skin known as TRPM8 (transient receptor potential cation channel subfamily M member 8). The breakdown of peppermint oil is approximately 7-48% menthol, 20-46% menthone, 3-10%, menthyl acetate, 1-17% menthofuran, and 3-6% eucalyptol, with small amounts of limonene, pulegone, caryophyllene, and pinene.
References: