The percentage of acetic acid in vinegar refers to the unit of measurement that focuses on the strength of the vinegar. This percentage has value because it has a correlation with the safety and efficiency of its food preservation and household use.
Not surprisingly, the higher percentage of acetic acid in the vinegar, the stronger the vinegar. Vinegar typically consists of a combination of acetic acid and water. More water dilutes the power of the acetic acid. People are able to consume vinegar with a low percentage of acetic acid, up to roughly five percent. Vinegar with a higher percentage of acid, around 20 percent, often has commercial uses, such as in herbicides. Vinegars with higher acetic acid levels sometimes cause damage, including skin, eye, nose and throat irritation, without proper safety measures such as goggles and gloves.
The percentage of acetic acid in vinegar has other effects, including an impact on the vinegar's shelf life. Vinegar with a low percentage of acid tends to be shelf-stable over time. Factors such as type of vinegar, container, packing method, storage and transportation have an affect on how stable the vinegar remains. However, even if the vinegar changes in color and clarity, it typically does not change in taste.