Sediment in mint vinegar is typically caused by the precipitation of plant matter, minerals, and naturally occurring compounds from the mint leaves as the vinegar ages. These particles are harmless and a natural part of the vinegar-making process.
Mint vinegar, like other herbal vinegars, is made by infusing vinegar with mint leaves. During this infusion process, various compounds from the mint leaves dissolve into the vinegar. These compounds include plant fibers, minerals, and other organic substances. Over time, these dissolved substances can begin to clump together and precipitate out of the solution, forming sediment at the bottom of the container. This process is accelerated by factors such as temperature fluctuations and exposure to light. The type of vinegar used (e.g., white vinegar, apple cider vinegar) can also influence the amount and type of sediment that forms. Apple cider vinegar, for example, naturally contains more sediment ('the mother') which can contribute to the overall sediment in the mint vinegar. Filtering the vinegar after infusion can help reduce sediment formation, but it won't eliminate it entirely as some compounds will still dissolve and potentially precipitate later.
To minimize sediment, store your mint vinegar in a cool, dark place. You can also filter the vinegar through a coffee filter or cheesecloth before bottling to remove larger particles. While sediment is harmless, filtering can improve the vinegar's appearance.