An acid is a chemical compound with a pH less than 7. Strong acids have a pH between 0 and 4, while weak acids have a pH between 4 and 7. All acids are hydrogen donors. An acid will give away a hydrogen to an alkaline compound called a base. Acids generally taste sour and corrode metals. While citric, ascorbic and sorbic acids all fall into the same broad category and share many similarities, they also have their own unique properties and characteristics.
Citric, asorbic and sorbic acid are all common compounds. Citric and asorbic acids both play an essential role in our body's biochemical processes and are part of a healthy diet. Citric and sorbic acids are used commercially as preservatives.
Citric acid is a tricarboxylic acid and is classified as a weak organic acid. Ascorbic acid is considered a carboxylic acid. According to Dr. Murli Dharmadhikari of Iowa State University, sorbic acid is a straight-chain unsaturated fatty acid that is highly reactive. It is often reacted with potassium to produce potassium salt for commercial use.
As its name implies, citric acid is a natural compound found in citrus fruits like oranges, lemons and limes. Its most famous biological role is in the citric acid cycle--an essential part of metabolism and energy production for many organisms. Citric acid is also used as a natural preservative in in some foods and drinks and is an environmentally friendly cleaning product.
Many fruits and vegetables, including oranges, spinach, tomatoes and berries, are rich in ascorbic acid--better known as vitamin C. Because ascorbic acid is water-soluble, the body cannot store it, and the vitamin must be obtained from dietary sources. Ascorbic acid is involved in wound healing, collagen production and bone and teeth support. According to the University of Maryland Medical Center, vitamin C deficiency can have very serious consequences, including hypertension, stroke and gall bladder disease.
Sorbic acid was first isolated from mountain ash berries in the 1800s and has since become a common ingredient in commercially produced food. Sorbic acid has both antimicrobial and antifungal properties--in other words, it inhibits the growth of some types of bacteria and fungi. Sorbic acid is often used in wineries because it prevents the growth of organisms that would spoil sweet wines.