The Official Chemical Name for Sorbic Acid
The primary and most accurate alternative name for sorbic acid is its systematic chemical name: 2,4-hexadienoic acid. This name precisely describes the molecule's structure. The name tells us it is a six-carbon molecule (hexa-) with two double bonds (-dien-), located at positions 2 and 4, and a carboxylic acid functional group (-oic acid). Sorbic acid is a colorless solid with a faint, characteristic odor. It is a fatty acid, which explains why the human body metabolizes it similarly to other fatty acids.
Other Chemical and Trade Designations
Beyond its official name, sorbic acid is sometimes referred to by other chemical descriptors or trade names, such as:
- (E,E)-2,4-Hexadienoic acid: This indicates the specific geometric isomer where both double bonds have a trans configuration, which is the form found in nature.
- 2-Propenylacrylic acid: This is another way to describe the chemical structure.
- Sorbistat: A former trade name for the substance.
The Food Additive Code: E200
In the food industry, sorbic acid is commonly identified by its European food additive code, E200. This code is recognized internationally and indicates its function as a preservative. Its salts, including potassium sorbate (E202) and calcium sorbate (E203), also have their own E numbers and are widely used due to their superior solubility in water compared to the acid form.
History and Origin of Sorbic Acid
The name "sorbic acid" comes from its original natural source, the berries of the mountain ash tree, whose scientific name is Sorbus aucuparia. German chemist A.W. von Hofmann first isolated the compound from these berries in 1859. While it was initially sourced naturally, the antimicrobial properties of sorbic acid were not discovered until the late 1930s and 1940s. Following this discovery, industrial production was established, primarily through chemical synthesis. Today, nearly all sorbic acid used commercially is synthetically produced.
Sorbic Acid vs. Its Salts: A Comparison
For food preservation, sorbic acid and its salts (primarily potassium sorbate) are often discussed interchangeably, but they have important differences that affect their application. The table below highlights the key distinctions.
| Feature | Sorbic Acid (E200) | Potassium Sorbate (E202) |
|---|---|---|
| Form | White crystalline powder | White granular or crystalline powder |
| Water Solubility | Slightly soluble (0.16 g/100 mL at 20°C) | Highly soluble (58.2 g/100 mL at 20°C) |
| Antimicrobial Activity | Active as the undissociated acid molecule | Dissociates in water to release active sorbic acid |
| Optimal pH | Effective at pH levels below 6.5 | Effective in the same pH range, but salts can slightly raise the food's overall pH |
| Primary Use | Dry products (cheeses, dried meats) | Aqueous products (beverages, dressings, sauces) |
How Sorbic Acid Functions as a Preservative
Sorbic acid's effectiveness comes from its ability to inhibit the growth of molds, yeasts, and some bacteria. It works by disrupting the microorganism's metabolic activity within its cells. The undissociated acid molecule can penetrate the cell membrane. Once inside, the sorbic acid molecule separates into ions, which lowers the cell's internal pH. To compensate, the microbe expends energy to restore its proper pH balance, a process that ultimately starves it of the energy needed for growth and reproduction. This mechanism makes it particularly useful for controlling spoilage in acidic or slightly acidic foods. As the pH of the food increases, more of the sorbic acid exists in its inactive, dissociated form, which is less effective.
Common Applications in Food, Cosmetics, and Pharmaceuticals
Sorbic acid and its more soluble salts are used in a wide array of products to extend shelf life and prevent spoilage. Some common applications include:
- Food Industry: Used in wines, cheeses, baked goods, fruit juices, and refrigerated meats and fish to inhibit mold and yeast.
- Cosmetics: Functions as a preservative in cosmetics and personal care products to prevent microbial contamination.
- Pharmaceuticals: Used as an antifungal preservative in various topical pharmaceutical products.
Because its metabolism within the body is similar to natural fatty acids, sorbic acid is considered a safe preservative. Its low toxicity and efficacy over a wide pH range make it a preferred choice over older preservatives like nitrates and sulfites in certain applications.
For more detailed chemical information, the National Institute of Standards and Technology (NIST) WebBook provides extensive data on sorbic acid's properties and identifiers.
Conclusion
In summary, while it is commonly known as sorbic acid, this natural and synthetic preservative has multiple identifiers. Its most descriptive and accurate name is 2,4-hexadienoic acid, reflecting its chemical structure. In the food industry, it's widely referenced by the additive code E200, while its highly soluble salts like potassium sorbate are preferred for many applications. Understanding these different names and its underlying mechanism explains why sorbic acid is a globally important ingredient for ensuring food safety and extending product shelf life.
