All food has an expiration date, but some people believe that vinegar gets better with age. A recent survey by a website found that nearly half of the people surveyed believe vinegar does not expire, firmly holding to the belief that "the older, the better."
According to China's "Regulations on the Management of Food Labeling," four types of food are exempt from having an expiration date: alcoholic beverages with an alcohol content of 10% or more, vinegar, edible salt, and solid edible sugar. A reporter checked the shelves of a supermarket for different types of vinegar and found expiration dates of two, three, and five years, with a very few not having an expiration date listed. So, what's going on?
A technician from a well-known vinegar factory in Jinzhong, Shanxi Province, explained that this is determined by the production process and acidity. The acidity of vinegar currently on the market generally ranges from 3.5 to 6 degrees. Vinegar with an acidity of 4.5 degrees or above is called "aged vinegar" (the Shanxi Vinegar Industry Association raised the standard for aged vinegar from 4.5 to 6 degrees in 2011), and most of it is brewed. Such aged vinegar can be stored for a long time without spoiling, even without any preservatives, so it generally does not require an expiration date.
Another type is blended vinegar, made by mixing acetic acid. Because this type is not produced using traditional methods, its acidity is difficult to reach 6 degrees, which can allow microorganisms to grow. Therefore, for vinegar with an acidity below 4.5 degrees, manufacturers generally must add food preservatives like sodium benzoate to ensure it lasts, and these types must have a shelf life. The vinegar on the market that is exempt from an expiration date generally refers to aged vinegar with an acidity above 4.5 degrees and containing no preservatives.
If it's an aged vinegar without an expiration date, it can theoretically be stored long-term, but the storage conditions at home are quite different from those in a vinegar factory. Even unopened vinegar can be affected by changes in temperature and other conditions, which can impact its quality. He Jiguo, a professor in the Department of Nutrition and Food Safety at China Agricultural University, suggests that if you find the vinegar has become cloudy, has sediment, or has an unusual taste, it should not be consumed.