Indigo Carmine (cl food blue 1)

E132, also known as indigo carmine or indigotin, is a synthetic blue dye used in the food industry. It is one of several artificial colours approved for use in food, pharmaceuticals and cosmetics. Indigo carmine is the sodium salt of indigotindisulfonic acid and gives products a vibrant blue colour.

Characteristics and uses in the food industry

Indigo carmine is of artificial origin. It is chemically synthesised, not obtained from natural sources. Production usually involves a series of chemical reactions, starting with indigo, a natural dye, which is then sulphonated to produce water‑soluble indigo carmine.

Properties

Indigo carmine is used in food products due to several key properties:

• Colour stability: It provides a stable and intense blue colour that remains consistent under different pH conditions and exposure to light.
• Versatility.
• Solubility: It is water soluble, which makes it easy to incorporate into a variety of food products.
• Safety: It is approved for use by food safety authorities in many countries under specific conditions of use.

Use in ultra‑processed foods

Indigo carmine is commonly used in ultra‑processed foods for several reasons:

• Visual appeal: It improves the appearance of food products, making them more visually appealing to consumers. This is especially important for products intended for children, such as candy, ice cream and beverages.
• Brand Consistency: Manufacturers use it to ensure consistent color across batches, which helps maintain brand identity and consumer confidence.
• Taste perception: Although it doesn't directly affect taste, food colour can affect taste perception. Bright, attractive colours can make products more palatable and appealing.
• Cost‑effectiveness: Synthetic colours such as indigo carmine are often more cost‑effective than natural colours, which is attractive to food manufacturers seeking to minimise production costs.

Impact on human health

Although indigo carmine is approved for use in many countries, there are some health aspects and potential risks associated with its consumption:

• Allergic reactions: Some individuals may experience allergic reactions or sensitivity to synthetic dyes, including indigo carmine. Symptoms can range from mild skin rashes to more severe reactions.
• Hyperactivity in children: Some studies suggest a possible link between artificial food colours and hyperactivity in children. This has led to calls for stricter labelling and, in some cases, reduced use in food products intended for children.
• Regulatory limits: Regulatory agencies such as the FDA and EFSA have set acceptable daily intakes (ADIs) to minimise potential health risks. It is important that consumers stay within these limits to avoid potential adverse effects.
• Warning: Synthetic blue dyes have no nutritional benefits and few studies have investigated their genotoxic and carcinogenic properties.

Sources

1. U.S. Food and Drug Administration (FDA). Food Additive Status List.
2. European Food Safety Authority (EFSA). Re‑evaluation of indigo carmine (E 132) as a food additive. EFSA Journal.
3. Scientific Opinion on the re‑evaluation of indigo carmine (E 132) as a food additive. EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS). EFSA Journal 2014;12(10):3768. doi:10,2903/j.efsa.2014,3768
4. Ristea ME, Zarnescu O. Indigo Carmine: Between Necessity and Concern. J Xenobiot. 2023 Sep 20;13(3):509‑528. doi: 10,3390/jox13030033. PMID: 37754845; PMCID: PMC10532910.