Permitted synthetic food dyes include Red dyes (Ponceau 4R, Azorubine, Erythrosine), Yellow dyes (Tartrazine, Sunset Yellow FCF), Blue dyes (Indigo Carmine, Brilliant Blue FCF), and the Green dye Fast Green FCF. These dyes are regulated by the FSSAI and must be pure and free of harmful impurities. Common analytical methods to analyze food dyes include spectrometric methods which measure absorption maxima, and chromatographic techniques like paper chromatography, thin layer chromatography, and column chromatography which separate dyes based on their properties.

1. Permitted Synthetic Dyes
Gagandeep
M. Pharm
(Pharmaceutical Analysis)

2. Colors in Food
 Colors are added to food and beverages to create an attractive appearance. They
enhance the color of foods which could have deteriorated due to food processing
as consumers would perceive such foods to be inferior.
 Color has an important implication as far as food is concerned as it plays a major
role in the taste and perception of food along with flavor and texture. It is a known
fact that if the food does not look attractive then consumers will probably reject it.
 However, if color is used to conceal damaged or inferior products so that it appears
better or greater in value then it could mislead the consumer.

3. Types of food colors:
Food colors are of two types: Dyes and Lakes.
1. Dyes dissolve completely in water and are available as powders, granules or
liquids. Dyes are used in beverages, dye mixes, dairy products, pie fillings, jams, pet
foods, etc.
2. Lakes are insoluble in water and are generally used in products that contain oils
and fats and in products that do not contain much moisture like coatings of
tablets, cheese, margarine, chewing gum, chocolates etc.

4. Permitted synthetic colorants
The FSSAI regulations for food coloring are covered under the category ‘Coloring
Matter’ in the Food Safety and Standards (Food Products Standards and Food
Additives) Regulations, 2011. The regulations say that no coloring matter may be
added to food unless permitted in these regulations. The colors specified in these
regulations, when used in the preparation of any article of food, shall be pure and free
from any harmful impurities.
The synthetic colors that are permitted to be used are mentioned below.
 Red from: Ponceau 4R, Azorubine and Erythrosine
 Yellow from: Tartrazine and Sunset Yellow FCF
 Blue from: Indigo Carmine and Brilliant Blue FCF
 Green from: Fast Green FCF

5. Ponceau 4R
• Ponceau 4R is a synthetic colorant that may be used as a food
coloring. It is denoted by E Number E124. Its chemical name is 1-(4-
sulpho-1-napthylazo)- 2-napthol- 6,8-disulphonic acid, trisodium
salt. Ponceau is the generic name for a family of azo dyes.
• Ponceau 4R is a strawberry red azo dye which can be used in a
variety of food products and is usually synthesized from aromatic
hydrocarbons.
• It is stable to light, heat, and acid but fades in the presence of
ascorbic acid.
• It is used in Europe, Asia and Australia, but has not been approved
by the US FDA.
Ponceau 4R

6. Azorubine
• Azorubine is an azo dye produced as a disodium salt.
• In its dry form, the product appears red to maroon.
• It is mainly used in foods which are heat-treated after fermentation.
• It has E number E122.
• It is also commonly known by name Carmoisine.
• Azorubine has shown no evidence of mutagenic or carcinogenic
properties and an acceptable daily intake (ADI) of 0–4 mg/kg was
established in 1983 by the WHO.
Azorubine

7. Erythrosine
 Erythrosine, also known as Red No. 3, is an organoiodine compound, specifically a
derivative of fluorone.
 It is cherry-pink synthetic, primarily used for food coloring.
 It is the disodium salt of 2,4,5,7-tetraiodofluorescein.
 Its maximum absorbance is at 530 nm in an aqueous solution.
 It is subject to photodegradation.
Erythrosine

8. Tartrazine
 Tartrazine is a synthetic lemon yellow azo dye primarily used as a food coloring.
 It is also known as E number E102, FD&C Yellow 5, Acid Yellow 23 and Food
Yellow 4.
 It is used for yellow color as such or mixed with Brilliant Blue to produce shades of
green.
 It has potential human risks of causing sensitivity and asthma.
Tartrazine

9. Sunset Yellow FCF
 Sunset Yellow FCF is a petroleum-derived orange azo dye.
 It has a pH dependent maximum absorption at about 480 nm at pH 1 and 443 nm
at pH 13.
 it is denoted by E Number E110.
 The acceptable daily intake (ADI) is 0–4 mg/kg. Sunset Yellow FCF has no
carcinogenicity, genotoxicity, or developmental toxicity in the amounts at which it
is used.
Sunset Yellow FCF

10. Indigo Carmine
 Indigo carmine, or 5,5′-indigodisulfonic acid sodium salt, is an organic
salt derived from Indigo.
 It is insoluble in water.
 It has the E number E132.
 It is also a pH indicator.
 This dye can cause a potentially dangerous increase in blood pressure in some
cases.
Indigo Carmine

11. Brilliant Blue FCF
 Brilliant Blue FCF (Blue 1) is an organic compound classified as a triarylmethane
dye and a blue azo dye.
 It is denoted by E number E133.
 It is soluble in water
 the solution has a maximum absorption at about 628nm.
Brilliant Blue FCF

12. Fast Green FCF
 Fast Green FCF is a sea green triarylmethane food dye.
 Its E number is E143.
 Fast Green FCF is poorly absorbed by the intestines.
 It is used as a quantitative stain for histones at alkaline pH after acid extraction
of DNA.
 Its absorption maximum is at 625 nm.
Fast Green FCF

13. Methods of Analysis
The two mainly used analytical methods are:
1. Spectrometric Methods
2. Chromatographic Methods

14. Spectrometric Absorption Maxima of Dyes:
Sr.
No.
Name of Dye Absorption Maxima
(nm)
1. Ponceau 4R 507
2. Azorubine 516
3. Erythrosine 527
4. Tartrazine 427
5. Sunset Yellow FCF 482
6. Indigo Carmine 609
7. Brilliant Blue FCF 630
8. Fast Green FCF 624

15. Chromatographic Determination
Chromatographic determination of dyes is a very simple procedure. The best
chromatographic technique used are
1. Paper Chromatography
2. Thin Layer Chromatography
3. Column Chromatography

16. Paper Chromatography
It is very basic chromatographic technique
involving no complex instrumentation.
Even no complex detection systems are
required because dyes being colored
compounds are visible easily.

17. Thin Layer Chromatography
It is also very simple method of detection as well as
separation.
It is very much similar to paper chromatography but
the only difference being that TLC is based upon
principle of ADSORPTION unlike PAPER which is
based upon PARTITION.

18. Column Chromatography
This method involves separation of
components on the basis of their
affinity for stationary phase.
Image shown is comparison of Column
Chromatography of a sample in
relation to TLC of the same.

19. References
 Ian P. Freeman, "Margarines and Shortenings" Ullmann's Encyclopedia of Industrial
Chemistry, 2005, Wiley-VCH, Weinheim doi:10.1002/14356007.a16_145
 Food Ingredients & Colors“, International Food Information Council. June 29, 2010.
Retrieved Feb 15, 2012
 https://foodsafetyhelpline.com/2016/07/function-of-colours-in-food-and-colours-
permitted-by-fssai-in-foods/ ~Accessed on 23/10/2018
 http://www.chem.ucla.edu/~harding/IGOC/C/chromatography.html ~Accessed on
24/10/2018