GELF berry wine is an unseen alcoholic beverage, made by GELFs from fruit.
After the genius mechanoid Butler saved the GELF Sakenyako tribe from illness, one of the rewards the Sakenyako bestowed upon Butler was a lifetime supply of GELF berry wine. Although Butler didn't drink, he found the liquid useful as a weedkiller for his gardens in the Nova 3. (Krysis, Series XI)