Tennessee whiskey is an alcoholic beverage originating from the U.S. state of Tennessee on Earth. Like other whiskeys, it is made from fermented grain mash, but is then filtered through maple charcoal before being aged in wooden barrels, giving it a distinctive flavor. The Jack Daniel's distillery in Lynchburg, Tennessee was the most famous producer of this particular variety of whiskey.
While camping on Earth during shore leave in 2287, Doctor McCoy used Tennessee whiskey in the beans he was cooking, saying it was an old southern recipe he had learned from his father. While Spock could not identify this "secret ingredient," Kirk did and asked McCoy for more of it. (TOS novelization: Star Trek V: The Final Frontier)
After hearing the eulogy of former President Jaresh-Inyo which Fred MacDougan wrote for President Nanietta Bacco on the three-hour trip from Earth to Mars, Presidential Chief of Staff Esperanza Piñiero resolved to reward him with a single-barrel Jack Daniel's. (ST novel: Articles of the Federation)
Piñiero had a glass of Jack Daniel's during her meeting with Sonek Pran in April of 2381, explaining that the restriction on alcoholic beverages at the Palais de la Concorde was suspended following the fall of Deneva, and never reinstated. (ST novel: A Singular Destiny)