1. Overview of Food Additives
Food additives are natural or synthetic substances added to food to improve its color, flavor, aroma, and texture, or to meet preservation and processing requirements. Currently, China classifies food additives into 23 categories, including acidity regulators, anti-caking agents, defoaming agents, and antioxidants. Among them, acidity regulators consist of 17 types, such as citric acid, potassium citrate, and lactic acid. Citric acid is one of the most widely used acidulants due to its excellent sour taste regulation.
2. Types and Characteristics of Citric Acid
(1) Anhydrous Citric Acid
Molecular formula: C₆H₈O₇
Properties: Colorless translucent crystals, white granules, or powder; odorless with an extremely sour taste; soluble in water, alcohol, and ether.
Applications:
- Food and beverage industry: Used as an acidulant, pH regulator, flavoring agent, preservative, and freshness enhancer.
- Chemical, cosmetic, and detergent industries: Functions as an antioxidant, plasticizer, and detergent component.
(2) Monohydrate Citric Acid
Molecular formula: C₆H₈O₇·H₂O
Properties: Similar to anhydrous citric acid but contains one crystal water molecule.
Applications: Nearly identical to anhydrous citric acid, suitable for food, beverages, chemicals, cosmetics, and detergents.
3. Differences Between Anhydrous and Monohydrate Citric Acid
There is no fundamental difference in chemical properties between the two. The main distinction lies in the presence of a crystal water molecule in monohydrate citric acid. However, since most food or industrial raw materials contain significant moisture, and the amount of citric acid added is relatively small, the crystal water has minimal impact on the final product’s water content. Therefore, in most cases, the two forms can be used interchangeably.
4. Trisodium Citrate Dihydrate
Molecular formula: Na₃C₆H₅O₇·2H₂O
Preparation: Produced by neutralizing citric acid with sodium hydroxide or sodium bicarbonate.
Applications:
- Food industry: Functions as an acidity regulator and emulsification enhancer.
- Pharmaceutical industry: Used for pH adjustment or as a buffering agent.
5. Conclusion
Citric acid and its derivatives (such as monohydrate citric acid and trisodium citrate dihydrate) play vital roles in food, chemical, and pharmaceutical industries. Understanding their properties and applications helps ensure their scientific and rational use, thereby enhancing food safety and quality.
