Caustic sulphite caramel
A dark brown food colouring made by heating sugars with sulphite compounds. Used mainly in vinegars, sauces, dark beers, brandies, and cola drinks.
Made with sulphite compounds, so trace sulphite residues remain. People with asthma are at heightened risk: between 5 and 13 percent of asthmatics react to sulphites with wheezing, chest tightness, or flushing. E150b may not carry a 'contains sulphites' warning unless residue in the finished product exceeds 10mg/kg, so sulphite-sensitive shoppers need to recognise the E number.
What is it?
One of four permitted caramel colours (E150a to E150d). Produced by heating food-grade carbohydrates such as glucose or sucrose in the presence of sulphite compounds, without ammonia. This process creates a dark brown pigment with a negative electrical charge, making it stable in acidic products. Also called caramel colour class II.
What does it do?
Gives food and drink a brown to dark brown colour. The negative charge it carries means it disperses evenly in acidic environments such as vinegar, cola drinks, and some spirits, without clumping or changing colour under heat or light.
Where you will see it
Vinegar, brown sauces and gravies, dark beers and stouts, brandy, cognac, sherry, some cola soft drinks, pickles, jams, ice cream, bakery fillings, savoury seasonings, and crisps. On UK labels it appears as 'colour (E150b)' or 'colour (caustic sulphite caramel)'. Scotch whisky regulations permit only E150a, not E150b.
What the science says
Sulphite residues and asthma risk
E150b is made using sulphite compounds, and sulphite residues can remain in the finished colourant. Sulphites are a recognised trigger for asthma attacks and sensitivity reactions. In the general population, sulphite sensitivity is estimated at under 2 percent, but in people with asthma the rate rises to between 5 and 13 percent. Reactions range from mild flushing and urticaria to wheezing, chest tightness, and, in rare cases, anaphylaxis.
Sulphite sensitivity affects an estimated 5 to 13 percent of people with asthma, causing symptoms including wheeze, chest tightness, coughing, and urticaria.
UK food law requires 'sulphites' to be declared on pack whenever sulphite content in the finished product exceeds 10mg/kg or 10mg/litre (as total SO2). E150b is named as a sulphite-containing additive that triggers this rule.
Sulphite residues in E150b products can be below 10ppm in many cases, meaning no allergen warning appears on the label even though the manufacturing process involves sulphite compounds.
Genotoxicity and carcinogenicity
The EFSA ANS Panel concluded in 2011 that caramel colours, including E150b, are not carcinogenic or genotoxic. Unlike class III (E150c) and class IV (E150d) caramels, E150b is not produced using ammonium compounds, so it does not generate 4-methylimidazole (4-MEI), an impurity that raises carcinogenicity questions for ammonia-process caramels.
EFSA's re-evaluation found caramel colours including E150b are not carcinogenic or genotoxic, and evidence does not indicate adverse effects on human reproduction or child development.
E150b does not generate 4-MEI because it is produced without ammonium compounds. The 4-MEI carcinogenicity debate applies to E150c and E150d, not to E150b.
Ames test mutagenicity assays across all four caramel colour classes, including class II, found no mutagenic activity with or without metabolic activation.
Dietary exposure and acceptable daily intake
EFSA established a group acceptable daily intake of 300mg per kilogram of body weight per day for caramel colours. For E150b specifically, exposure estimates for both adults and children were below that level, unlike three of the other caramel classes where some population groups were estimated to exceed the ADI.
EFSA set a group ADI of 300mg/kg body weight per day for E150a, E150b, and E150d. Dietary exposure to E150b was estimated to be below the ADI across all population groups assessed.
Where it stands with the regulators
Who should be careful
People with sulphite sensitivity or sulphite-triggered asthma. Reactions can occur even at low residue levels. Look for 'E150b', 'colour (caustic sulphite caramel)', or a 'contains sulphites' statement in the ingredients list. Note that products using E150b with sulphite residues below 10mg/kg are not legally required to carry a sulphite warning, so the E number itself is the clearest signal.
The honest read
The main real-world issue with E150b is the sulphite residues it carries as a byproduct of manufacture. Sulphites are one of the 14 major UK allergens, and E150b is explicitly named in Allergy UK guidance as a sulphite source. The practical complication is that residue levels are often below the 10mg/kg declaration threshold, so products containing E150b may not flag sulphites on the label at all. For the general population the exposure picture is unremarkable: dietary intake of E150b sits comfortably below the group ADI in EFSA's modelling, and the colour raises none of the carcinogenicity questions that follow ammonia-process caramels (E150c, E150d). But for the several percent of asthmatics who react to sulphites, the absence of a label warning makes E150b a hidden trigger worth knowing by name.
Related additives
Common questions
Is E150b banned in the UK?
No. E150b is approved for use in the UK under the assimilated EU Regulation 1333/2008 as a food colour authorised at quantum satis (no specified maximum level). It appears on the UK FSA's approved-additives list.
Does E150b contain sulphites and could it trigger a reaction?
Yes. E150b is produced using sulphite compounds, and sulphite residues can remain in the finished colour. Sulphites are a recognised asthma and sensitivity trigger. Between 5 and 13 percent of people with asthma react to sulphites. If sulphite residue in the finished food product is below 10mg/kg, UK law does not require a 'contains sulphites' warning, so the E150b E number may be the only indication on the label.
What foods contain E150b?
Vinegar, brown sauces, gravies, some dark beers and stouts, brandy, cognac, sherry, certain cola drinks, pickles, jams, ice cream, bakery fillings, and savoury seasonings are common carriers. Scotch whisky regulations require E150a (plain caramel) only, so Scotch does not contain E150b.
Is E150b vegan?
The colouring itself is produced from plant-based carbohydrates and sulphite compounds with no animal-derived ingredients in the process. Some strict vegans query whether the sugar feedstock was processed through bone char, which is used in some cane sugar refining, but this is not specific to E150b and UK beet sugar is typically bone-char-free. Most E150b products are considered vegan.
Sources
- EFSA ANS Panel Scientific Opinion on the re-evaluation of caramel colours (E 150 a,b,c,d) as food additives, EFSA Journal 9(3):2004
- UK FSA Approved Additives and E Numbers
- UK FSA Regulated Products: E150b Caustic sulphite caramel
- Allergy UK, Sulphites and Airway Symptoms factsheet
- Anaphylaxis UK, Sulphites fact sheet
- UK FSA Food Allergen Labelling and Information Requirements Technical Guidance
- EFSA reviews safety of caramel colours (press release)
- EFSA establishes new ADIs for caramel colours, FoodNavigator
- Caramel color safety: An update, Food and Chemical Toxicology (ResearchGate)
- Scotch Whisky Regulations 2009, UK Government guidance
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