Mold on top of homemade cider vinegar

Asked March 19, 2019, 3:52 PM EDT

I am curious about the safety of the last batch of cider vinegar I made. I have successfully made cider vinegar in the past by pressing apples and placing the raw cider into a carboy. The mouth of the carboy was covered in cheese cloth and the cider was left in a cool dark area for several months. When I recently checked on this particular batch, I noticed a layer of mold on top of the mother. I carefully transferred the vinegar to a separate container, but the vinegar did come in contact with the mold. The Vinegar tastes good, but I am concerned about the mold aspect. the mold was a blue/green/white color. Is it safe to use for cooking? Cleaning? Any input would be helpful; including suggestions on preventing mold from forming on future batches. Thank you! Bryan

Multnomah County Oregon

1 Response

The mold you see on top of the mother is the bloom, indicating that there are tendrils and spores of mold throughout the product, including the liquid vinegar. I would consider this entire product contaminated. Ongoing research indicates that mold is of greater concern than previously believed. I would not recommend any consumption of the vinegar. I am reluctant to recommend it for cleaning purposes because the mold count is unknown, so you may be spreading mold spores as you use it.

The presence of mold could mean that either the mother had already been contaminated or there was not excellent hygiene and cleanliness when preparing and handling the vinegar. Sterilizing containers and making sure all utensils, hands, surfaces are clean will reduce chances of a future contamination. If there is a heavy load of mold in the air, open containers are also likely to be exposed. Keeping the product covered will help. Temperature control also slows or controls some mold growth. 60-80’ seems to be ideal.

Raw apple juice will have mold spores from the environment, there’s no way to avoid this. To reduce the load, scrub apples with a brush, cut away any spoiled portions; removing the stem and blossom ends reduces trapped mold and soil. Bacteria is also of concern with apples. We recommend pasteurizing the juice for drinking.

Here are a couple of resources that may be of interest.