Mother Knows Best
As a child, I asked my mom what the thick stuff in the vinegar jar was. She called it "mother." Is it harmless? —K.L., Mohawk, New York
Your mother was correct. The gelatinous substance in the vinegar jar, called "mother," is actually cellulose and acetobacter. Acetobacter is the bacteria that digest alcohol and produce acetic acid, giving vinegar its sour flavor. Typically, only unpasteurized vinegars develop mothers. Occasionally, commercially pasteurized vinegars will develop them, too.
Vinegar containing mother is not harmful or spoiled. To remove the mother, simply strain vinegar through a clean coffee filter and store it in a clean container.