Sometimes a mold-like growth appears inside a bottle of opened vinegar. Does this mean the vinegar has gone bad?
The growth is called a “mother” and it’s cellulose that naturally occurs in vinegar, produced by those harmless bacteria mentioned earlier. It doesn’t mean the vinegar is spoiled or in any way harmed. Vinegar producers usually pasteurize the product to prevent a mother from occurring, but should one develop in one of your bottles, simply pour the vinegar through a filter (a fine mesh sieve or coffee filter would work), discard the “mother,” and then enjoy the vinegar.
