U.S Code of Federal Regulations defines that acid and acidified food as foods having a pH of 4.6 or lower.
Acids are used to decrease the pH of foods. By doing so, they can improve its microbial stability and impact its taste by imparting their own flavor and modifying the taste perception of other ingredients. By improving the food's microbial stability, the acids can be used as preservatives in acidification processes.
Generally, it is not possible to preserve all foods by adding acid to the point where no microorganisms will grow. Most foods would be too acid to be palatable. Enough acid may be used to inhibit the growth of microorganisms provided that such treatment is combined with some other method of preservation.
Methods of drying and/or addition of salt or sugar to foodstuffs are often combined with a reduce pH – increase acidification.
Food preservation: Acidification
