When reviewing ingredient lists on processed foods, the code tartrazine often appears alongside the colour descriptor yellow, a pairing that signifies the synthetic azo dye Yellow 5. This specific substance, identified by the E number E102, is responsible for the vibrant yellow hue in everything from soft drinks to icing, and its regulation is a serious matter for food authorities globally. Understanding the code is essential for both industry professionals who need precise formulation data and consumers who are monitoring their intake.
The Official Identification: E102 and INS No. 102
The primary yellow food colouring code you will encounter on European and international packaging is E102, which stands for the European Union's E number system for food additives. This alphanumeric code is part of the International Numbering System (INS), meaning you will also see INS No. 102 on labels worldwide. This standardized system allows for clear identification across different languages and regulatory environments, ensuring that manufacturers and regulators are always referring to the exact same chemical compound.
Chemical Identity and Nomenclature
While the code provides a reference, the chemical identity of Yellow 5 is disodium 1-(4-sulfonatophenyl)-4-[(4-sulfonatophenyl)diazenyl]-2-pyrazolin-5-one. It is the sodium salt of tartrazic acid, which is why it is commonly referred to as tartrazine. The molecule is a synthetic lemon yellow azo dye, meaning it contains the azo functional group (-N=N-) responsible for its chromophore, the part of the molecule that absorbs specific wavelengths of light to produce the yellow colour we perceive.
Global Regulatory Codes and Compliance
Beyond the E/INS system, yellow food colouring is tracked through various national and regional codes. In the United States, it is certified as FD&C Yellow 5 under the Federal Food, Drug, and Cosmetic Act, with the Colour Index (CI) number CI 19140 serving as a standardized reference in scientific and manufacturing contexts. These different coding systems—E numbers, FDC numbers, and CI numbers—all point to the same entity, ensuring consistency whether a product is sold in Berlin, New York, or Tokyo.
Usage Specifications and Legal Limits
The code dictates not just the identity but also the permissible usage levels. Regulatory bodies such as the European Food Safety Authority (EFSA) and the US Food and Drug Administration (FDA) establish Acceptable Daily Intakes (ADI) and maximum limits for specific foods. For tartrazine, the ADI is set at 0.7 milligrams per kilogram of body weight per day. These limits are based on toxicological studies and are designed to ensure that consumption within the general population remains safe over a lifetime.
Practical Applications in the Food Industry
For food manufacturers, the yellow food colouring code is a shorthand for a specific set of physical and chemical properties. It is highly soluble in water and provides a bright, clear lemon yellow that is stable under a wide range of pH conditions, although it can be sensitive to fading in the presence of certain metals or light. Consequently, you will find it used in formulations for beverages, desserts, confectionery, and sauces where a vivid and consistent colour is required.
Labeling and Consumer Information
From a consumer perspective, the code is your direct line of information. On a product label, you will typically find the name "Tartrazine" or "Yellow 5" followed in parentheses by the code E102. This practice is mandated by law in many jurisdictions to ensure transparency, allowing individuals with sensitivities—who may experience mild allergic reactions—to make informed choices and avoid specific ingredients.
