Loqua is a drink made from Loquat Berries which were found in the amazon rainforest. The name is likely derived from the word "liquor".
Loqua is an extremely popular beverage among Air Pirates, and all sailors and traiders within the world of Arcadia. Gordo, the black pirate encountered during the game, uses it to execute his special attack "Loqua Spray."
The original Japanese Dreamcast version has characters drinking rum, an alcoholic drink deeply associated with pirates. This change was most likely done to remove references to alcohol.
Despite the unintended swap, Loqua developed its own interesting background. As the player explores the game, there are several opportunities to examine objects and garner small bits of info about Loqua. From these pieces of information it becomes apparent that there are actually 6 types of loqua, one made with each type of moonstone. Relik Loqua for example, is made with red moonstones and, as Vyse notes, is rather spicy as a result. There is also a variety of Relik Loqua called Khale-Relik Loqua made with both Khale spice and red moonstones, nicknamed the "Taste of the Desert". Mur Loqua contains blue moonstones, and Vyse notes it is one of the more popular varieties among sailors. New World Loqua is available at Gordo's Bistro and is likely made with either green or blue moonstones. At Polly's Tavern there is a bottle of Gerdin Loqua on one of the shelves, Vyse notes that it is "too green" for his tastes. At Nasrad there are barrels of an unnamed Loqua from Valua. Yellow and purple loqua do not seem to be mentioned. Vyse once ponders over the possibility of silver loqua even existing, and wonders what it would be like.