Caramel colour IV (sulphite-ammonia)

Caramel colour IV (E150d) is produced by heat treating food-grade carbohydrates in the presence of both ammonium and sulphite compounds. It is the most widely used caramel colour type in the food industry, particularly in cola-flavoured soft drinks, soy sauce, and certain gravies, where its strong brown colouration and stable negatively charged colloidal properties are valued. The sulphite-ammonia process gives it specific physicochemical characteristics that suit high-acid carbonated beverages.

JECFA evaluated Caramel colour IV in 1984 and established an ADI of 0–200 mg per kg body weight per day, expressed as caramel solids. No EFSA numerical ADI is recorded in the EFSA OpenFoodTox 3.0 database. A notable concern with the sulphite-ammonia process is the formation of 4-methylimidazole (4-MEI), a by-product classified as possibly carcinogenic to humans by IARC (Group 2B, 2011). Regulatory specifications in several markets limit the 4-MEI content of caramel colour IV to mitigate consumer exposure.

The IARC Group 2B classification of 4-MEI in 2011 prompted regulatory attention globally. California Proposition 65 requires warnings on beverages with 4-MEI above specified thresholds, and major soft drink manufacturers reformulated or shifted production methods to reduce 4-MEI levels. The additive remains permitted in the EU, US, Japan, South Korea, and most markets subject to purity criteria including maximum 4-MEI concentrations. Consumers who wish to minimise 4-MEI exposure can look for products formulated without caramel colour or using plain caramel colour (E150a) instead.