In September 2000 1, China issued the standard of total acid content in vinegar, which requires that the vinegar degree should not be lower than 3.5g per100 ml. If it is less than 3.5 grams, it is not only inebriate, but also easy to be contaminated by bacteria, so it is not suitable for preservation. 6-degree water tower mature vinegar means that the total acidity is 6 grams per100 ml.