339. Wine Vinegar

47:9 If a non-Jew poured water into uncooked wine, if his intention was to make a beverage of it, it is prohibited. If his intention was not to serve the resulting mix – or even if we just don’t know his intention – then it is permitted.

If vinegar made from kosher wine is so strong that it bubbles when poured on the ground, then it does not become prohibited if touched by a non-Jew. If, however, it was made from non-Jewish wine, then it remains prohibited forever.