Related על תענית 59:16

It so happened that a dead snake was found in a wine cistern and they came and asked Rabbi Yehudah ben Bava, and he [ruled that] the cistern remained permissible [as the] wine was fermenting. As long as it is still fermenting, it is not subject to the prohibitions of exposed liquids (Sanh. 70a:10). And how long does it ferment? Three days.