caramel colours
compound class / compound-class-caramel-colours
カラメル色素 / caramel colours (Class I-IV)
Caramel colours: a group of food additive colorants generated by heating carbohydrates, classified into 4 classes by JECFA (FAO/WHO Joint Expert Committee on Food Additives) based on manufacturing method.
On this page (6 sections)
Reading the bitterness
Caramel colorant is a food additive coloring made by heating carbohydrates. The FAO/WHO Joint Expert Committee on Food Additives (JECFA) classifies it into 4 classes based on manufacturing method: Class I is plain caramel in which carbohydrates are heated with alkali or acid; Class II uses sulfite compounds together; Class III is ammonia caramel using ammonium compounds together; Class IV uses both ammonium compounds and sulfite compounds together. The regulatory document defining this manufacturing-based classification contains no description of bitterness.
Interest in bitterness arose from research that used bitterness as an index to fractionate and identify commercially available Class III. In this research, four compounds—DDMP (2,3-dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one), HMF (5-hydroxymethylfurfural), furfural, and 5-methylfurfural—were isolated and their structures determined as major bitter compounds, with bitter taste threshold concentrations reported as 14.3, 30.0, 4.4, and 17.5 µmol/L respectively. Volatile bitter compounds DMFM and TMP were also separately identified.
This finding is specific to Class III (ammonia caramel), 1 class in the regulatory standard, and cannot be directly applied to Class I, II, IV, or caramelization in general that occurs from cooking heat in food. The publisher's website could not be directly accessed; content was confirmed through matching bibliographic information across multiple academic databases, and final verification of the values requires comparison with the paper's text.
The JECFA specification uses, in addition to the reactants used in manufacture, the rate of decrease in 560 nm absorbance when the colorant is bound to cellulose and the 280 nm/560 nm absorbance ratio to classify Class I–IV. For Class I, the percentage of color bound to both types of cellulose is 50% or less; for Class III, the percentage of color bound to DEAE cellulose is 50% or less while the percentage bound to phosphorylated cellulose exceeds 50%; and the criteria differ by class in this way. This is an identification method under the specification based on color measurement, not a test that classifies taste.
There is also an example that directly measured bitterness when added to food. In a study that prepared 3 products each of Class I, III, and IV, 9 products in total, and added them to huangjiu (Chinese rice wine) at 0.20% (w/v), all 3 classes had higher bitterness intensity than the no-addition control on a 10 cm line scale rated by 10 experienced assessors (p<0.05). Class II was not tested, and this is a result for a specific huangjiu and commercial products.
When the same study varied the amount added among 0.03%, 0.10%, and 0.20% (w/v), a significant increase in bitterness intensity with increasing amount added was shown for each of Class I, III, and IV (p<0.05). This range is a result of 10 experienced assessors evaluating a specific huangjiu and products from 3 companies. It is not a result that estimated bitterness from color depth or the amount of a chemical component, nor does it predict the bitterness of other beverages or dishes.
Sources for this overview
Caramel Colours — Classes I, II, III and IV (WHO Food Additives Series 20)
Checked for this overview: Confirmed 4-class definition by JECFA based on chemicals used
Identification of bitter-taste compounds in class-III caramel colours
Checked for this overview: Confirmed 4 major bitter compounds and threshold concentrations / Limitation of applicability: Class III only
Checked for this overview: Used for the 560 nm bound-color percentage, the 280/560 nm absorbance ratio, the 50% criteria for Class I and III, and the limitation that this is not a taste test.
Effect of caramel colors addition on the color, physicochemical properties, and flavor of Huangjiu
Checked for this overview: Used for the 3 products each of Class I, III, and IV, 0.20% w/v, 10 huangjiu assessors, the 10 cm line scale, the bitterness increase over the control at p<0.05, and the limitation that Class II was not included. / Used for the bitterness increase with the amount added at p<0.05 for each tested class over the 0.03/0.10/0.20% w/v range, and the limitation of a specific huangjiu, products from 3 companies, and 10 assessors.
Structured claims — open a section to read each claim's confidence, evidence and limits
Sensory (3)
Scope: A sensory-guided fractionation study of commercial Class III caramel coloring
Note: This is a finding for Class III (ammonia caramel), 1 regulatory class among several, and cannot be extrapolated to Class I/II/IV, or to non-standardized caramelization occurring through heating in food in general.
Show data
compound-class-caramel-colours —has_key_bitter_organoleptics→ "Sensory-guided fractionation and identification, using bitterness as the index, was carried out on commercial Class III (ammonia caramel) coloring, and 4 compounds — DDMP (2,3-dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one), HMF (5-hydroxymethylfurfural), furfural, and 5-methylfurfural (MF) — were isolated and structurally identified as the main bitter compounds. Their threshold concentrations are reported as 14.3, 30.0, 4.4, and 17.5 µmol/L respectively. DMFM and TMP were also separately identified as volatile bitter compounds."Scope: Zhou et al. 2024; 9 products from 3 companies (3 products per class); 10 experienced huangjiu assessors; 10 cm unstructured line scale; 3 replicates.
Note: Class II was not tested. This is a result for a specific huangjiu and commercial colorant products, and it is not generalized to all products of each class or to other foods.
Show data
compound-class-caramel-colours —has_perceived_bitterness_affected_by→ "In a test where 0.20% (w/v) was added to huangjiu, Class I, III, and IV all significantly increased the bitterness intensity of the huangjiu compared to the no-addition control (p<0.05)."Scope: Zhou et al. 2024; a specific huangjiu; 9 products from 3 companies; 10 experienced huangjiu assessors; 10 cm unstructured line scale; 3 replicates.
Note: This shows the direction across the 3 concentrations, but it does not show a bitterness ranking among classes, untested concentrations, Class II, or a dose response for other foods.
Show data
compound-class-caramel-colours —has_perceived_bitterness_affected_by→ "In a test that increased the amount added to huangjiu among 0.03%, 0.10%, and 0.20% (w/v), a significant increase in bitterness intensity with the increasing amount added was shown for each of Class I, III, and IV (p<0.05)."Safety and regulation (2)
Scope: Manufacturing-based classification from WHO Food Additives Series 20 monograph
Show data
compound-class-caramel-colours —is_classified_by→ "JECFA (FAO/WHO Joint Expert Committee on Food Additives) classifies caramel colorant into the following 4 classes by manufacturing method: Class I (Plain/Caustic Caramel: controlled heating of carbohydrates with alkali or acid), Class II (Caustic Sulfite Process Caramel: controlled heating of carbohydrates with sulfite compounds), Class III (Ammonia Caramel: controlled heating of carbohydrates with ammonium compounds without sulfite compounds), Class IV (Sulfite Ammonia Caramel: controlled heating of carbohydrates with both ammonium compounds and sulfite compounds)."Scope: The IDENTIFICATION and Classification tests in the 55th JECFA (2000) specification.
Note: An identification method under the specification, added to the definition by the reactants used in manufacture. This is a colorimetric and binding test, not a method that classifies taste or perceived intensity.
Show data
compound-class-caramel-colours —is_classified_by→ "The JECFA specification classifies Class I–IV by combining the percentage of color bound to DEAE cellulose or phosphorylated cellulose with the 280 nm/560 nm absorbance ratio."