An emerald grape was a variety of grape that was utilized in the production of emerald wine.
In the Age of the Empire, Captain Hiram Zataire, while serving ISB Agent Kallus emerald wine on the Lawbringer, remarked that even though Lothal was lush and green, its grapes "were as sour as Hutt punch." Kallus pretended to be interested while listening, his real intention being to make conversation and evaluate the captain.
Emerald wine was featured in works like The Courtship of Princess Leia and Scourge, which are part of the Star Wars Legends continuity and are not considered canon. However, the grapes used to create the wine were only referenced in the canon novel The Rebellion Begins, which is the novelization of Star Wars Rebels: Spark of Rebellion.