The popular preservative, Potassium Sorbate, will prevent fermentation. It's actually used to assist in back sweetening wine....allowing you to add fermentable sugar or juice but preventing the fermentation.....I do it with apfelwine.
Something is always fermenting....
"It's Bahl Hornin'"
Kegged: Sour Saison, Pale Ale, Aggie Ale, Firestone DBA, De Koninck Blonde
Bottled: Belgian Quad (Grand Reserve), Derangement (Belgian Dark Strong)
On Deck: Pliny the Younger