Classification of colorants

Classification of colorants

Classification of Colorants

Color Additives Exempt from Certification Permanently Listed for Use in Foods

Color Additives Exempt from Certification Permanently Listed for Use in Foods

Synthetic Color Additives Allowed for Use in Food Worldwide

Synthetic Color Additives Allowed for Use in Food Worldwide

Common Applications of the FD&C Certified Colorants

Common Applications of the FD&C Certified Colorants

Certified Color Additives Permanently Listed for Use in Foods

Synthetic Colorants

Inorganic PigmentsSynthetic Pigments

Serious health problems associated with inorganic pigments led to legislation

• Pickles colored green with copper sulfate • Cheese colored with vermilion (HgS) and red

lead (Pb3O4)

• Tea leaves colored with copper arsenite, lead chromate, and indigo

• Candies and other confectioneries pigmented with lead chromate, red lead, vermilion, and white lead (lead carbonate).

Present status of inorganic food colorants

• Some inorganic compounds are still used as colorants in foods– Mainly because of their other properties, although they

also contribute to color

• Calcium carbonate– as an anticaking agent, acidity regulator, emulsifier, and

stabilizer – but it also contributes to color

• Magnesium chloride and magnesium hydroxide are also food additives that contribute to food color

Inorganic pigments used in foods

• Titanium dioxide• Carbon black• Ultramarines (ultramarine blue)• Calcium carbonate• Iron oxides and hydroxides• Silver, gold, and aluminum

Titanium dioxide• TiO2 is an intensely white

pigment; • Exhibits excellent stability

toward light, oxidation, pH, and microbiological attack

• TiO2 is found in three crystalline forms in nature: – anatase, brookite, and rutile

• Virtually insoluble in all common solvents but soluble in mineral acids

Sulfate process

Chloride process

TiO2 commercial presentations are inwater- and oil-dispersible forms

Food applications of TiO2

• Only grades of the highest purity are permitted– Uncoated anatase pigments, with higher TiO2 content, between 95

and 99% are gener

• TiO2 is approved for use in general for coloring foods– the quantity added must not exceed 1% by weight of the food

• Sugar-panned confectionery to give an opaque white finish or as background to other colors

• The approval for drugs and cosmetics is in accordance with GMP

• Xanthan gum at 0.05/kg stabilizes the dispersion of TiO2 – providing the best whitening characteristic and without undesirable

effects

Applications of TiO2

• Dairy products (renneted milk, pasteurized cream, sterilized and UHT fat creams)

• Fresh meat, poultry, and game; whole pieces or cuts• Fresh, frozen, and cooked marine products (fish,

mollusks, crustaceans, and echinoderms)• Fresh eggs• Infant food formulae• Wines (sparkling, semisparkling, and aromatized)• Fresh meat, poultry, and game; comminuted• As a barrier film, by coating glass containers to

protect sensitive foods from light

Carbon black• Composed of

– a fixed content of carbon (80 to 96%) and volatile compounds

• Its particles are of colloidal size (20 to 65 μm)• Method of production

– Controlled combustion of natural gas followed by ignition against a mobile surface of cold iron where carbon black is deposited

– Conditions must be carefully controlled to obtain particles of the desired characteristics

• Its use in color foods is very limited– In Europe it is utilized in sugar confectionery– Not Approved by US FDA

Ferrous gluconate

Fine powder

Yellowish-gray orpale greenish-yellow

Used for enhancing the color of ripe olives

Ultramarines (ultramarine blue)• Synthetic colors of indefinite composition

– complex combination of silica, alumina, sodium oxide, and sulfur– empirical formula Na2Al6Si6O24S3

– highly resonating polysulfide linkages produce the color– originally intended to mimic the color of the semiprecious gem lazurit

• Method of production– Mixing kaolin (China clay), silica, sulfur, soda ash, sodium sulfate, and

carbonaceous reducing agent (e.g., rosin, charcoal pitch) at (up to 800°C/24 h) followed by slow cooling

– Calcinated materials are washed, wet-milled, dried, milled, and packed.

– Different colors are obtained by manipulation of ingredients and process conditions.

Ultramarines

• Insoluble in water and organic solvents• Used to impart a blue color to the products– range of colors extends from violet or red to green

• Ultramarines are permitted 0.5% color concentration in feed preparation as a salt source

• Widely used in cosmetics

Calcium carbonateFound in nature as chalk, limestone, marble, and feldspar

Calcium carbonate is neither toxic nor dangerous to health

Calcium carbonate has not beenapproved as a food color additive by the FDA

The FDA classifies calcium carbonate as a GRAS

White colorant of certain foods

Ingredient in chewing gum, toothpaste, and sometimes in sugar confectionery instead of titanium dioxide

Synthetic calcium carbonate is also utilized as a filler in plastics for packing food

Permitted Use of Calcium Carbonate for Foods

• Renneted milk, sterilized, and UHT fat creams GMP• Flours and starches• Fresh meat, poultry, and game; whole pieces or cuts• Fresh, frozen, and cooked marine products (fish, mollusks, crustaceans,

and echinoderms)• Infant food formulae• Canned or bottled (pasteurized) fruit juice• Pasteurized cream• Sterilized, UHT, whipping or whipped, and reduced fat creams• Whole, broken, or flaked grain, including rice• Fresh meat, poultry, and game; comminuted• Salt • Wines

Iron oxides and hydroxides

• All iron oxide pigments meet the FDA requirements for plastics, pigments, or inks in contact with food

• According to all legislation they are defined as inorganic pigments and are used as food additives

• Iron oxide red – other names are pigment red 101, bright red iron oxide, Indian red,

Turkey red, and ferrite red, among others);

• Ferrite yellow– also known as synthetic ocher, ferrite oxide monohydrate, iron oxide

yellow, or pigment yellow 42

• Iron oxide black

Direct precipitation method for yellow iron oxide

Penniman-Zoph or scrap process for yellow iron oxide

Iron oxide black by precipitation process

Calcination of ferrous sulfate for red oxide

Iron red oxides do not exhibit the color purity or the high chroma of the organic pigments but their price is one quarter to one tenth lower

Aniline process for yellow iron oxide

Iron oxides and hydroxides

• Iron oxides are insoluble in most solvents but usually soluble in hydrochloric acid.

• Permitted by the FDA at levels not exceeding 0.25% by weight in fish pastes and pet foods

• Also permitted in pharmaceutical and cosmetological applications

• Preferred choice when products are manufactured by severe heat treatments

Silver, gold, and aluminum

• Use of these metals in foods is not approved by the FDA

• Used as a finely divided powder or leaf for confectionery items and cake decorations – in Middle and Far Eastern countries

Chemical classes of synthetic colorants

• Azo dyes: – Allura red (E129), sunset yellow (E110) and tartrazine

(E102)• Triarylmethane dyes: Brilliant blue (E133) and fast

green• Indigoid dyes: Indigotine (E132)• Arylmethane dyes• Xanthene dyes: Erythrosine (E127)• Quinoline dyes• Anthraquinones• Phenols

Allura red (E219)

• CAS No. 25956–17–6• Chemical names

– 6-Hydroxy-5-((2-methoxy-5-methyl-4-sulfophenyl) azo)-2-naphthalenesulfonic acid disodium salt

– 6-Hydroxy-5-((6-methoxy-4-sulf-o-m-tolyl) azo)-2-naphthalenesulfonic acid disodium salt

• Synonyms– FD&C red No. 40; C.I. 16035; C.I. food red 17

• Properties– Dark red powder solubility at 25°C; water

22.5%; 50% alcohol, 13%; low solubility in glycerol and polyethyleneglycol

Maraschino cherries Gelatin dessertsIce cream and frozen dessertsBeveragesDry powdered drinksCandy and confectionery products that are oil and fat freeBakery products Cereals, and puddings

Maximum permittedlevel in fermented milk is 50 mg/kg and in other products is 300 mg/kg

Chemical synthesis of Allura red

Synthesis of Sunset yellow (E110)

Sunset yellow (E110)• CAS No. 2783–94–0• Chemical name(s)

– 6-Hydroxy-5-((4-sulfophenyl) azo)-2-naphthalenesulfonic acid disodium salt

• Synonyms – 1-p-sulfophenylazo-2-naphthol-6-

sulfonic acid disodium salt; FD&C yellow No. 6; C.I. food yellow 3; C.I. 15985

• Physical data – Orange red crystals; absorption max.

(0.02 N CH3COONH4): 480 nm; – soluble inwater; slightly soluble in

ethanol; – forms a reddish-orange solution in

concentrated sulfuric acid, changing to yellow on dilution

• Maximum level of 300 mg/kg

Gelatin desserts,Dairy-based desserts (ice cream and frozen desserts), Beverages,Dry powdered drinks, Candy and confectionery products that are oil and fat free,Bakery products, Cereals, puddings, Fruit based desserts,Dried vegetables,Fermented vegetable products, Sugars and table top sugars, Water-based flavoredDrinks and snacks, among others

Tartrazine (E102)

• CAS No. 12225–21–7• Chemical name(s)

– 5-Oxo-1-(p-sulfophenyl)-4-[(p-sulfophenyl) azo]-2-pyrazoloine-3-carboxylic acid

• Synonyms – C.I. 19140:1; C.I. food yellow 4; C.I.

pigment yellow 100• Physical data

– Bright orange-yellow powder; – freely soluble in water; – the aqueous solution is not changed by

HCl but becomes redder with sodium hydroxide

• Permitted levels– 300 mg/kg in all of its applications

Uses of Tartrazine• Gelatin desserts, dairy-based desserts (ice cream and frozen

desserts), • Beverages, dry powdered drinks, • Candy and confectionery products that are oil and fat free, • Bakery products, cereals, puddings, • Fruit-based desserts, fruit fillings for pastries, • Dried vegetables, fermented vegetable products, • Precooked or dried pastas and noodles, • Egg-based desserts (e.g., custards), • Sugars and table top sweeteners, • Water-based flavored drinks, • Beverage whiteners and snacks, among others

Synthesis of Tartrazine E102

Stage I

Stage II

Brilliant Blue (E133)• CAS No. 3844–45–9• Chemical name(s)

– N-Ethyl-N-(4-((4-(ethyl((3-sulfophenyl) methyl) amino) phenyl) (2-sulfophenyl) methylene)-2,5-cyclohexadien-1-ylidene)-3-sulfobenzenemethanaminium inner salt, disodium salt

• Synonyms – FD&C blue No. 1; C.I. acid blue; C.I. food blue 2; C.I. 42090

• Physical data – Reddish-violet powder or granules with a metallic luster; absorption

max.: 630 nm;– solubility in water and ethanol; – practically insoluble in vegetable oils; – forms a pale amber solution in concentrated sulfuric acid, changing to

yellow then greenish-yellow on dilution; – solubility in glycerol and polyethylene glycol is similar to that in water

Stage 1. Condensation

Stage 2. Oxidation

Synthesis of Brilliant Blue

Uses o Brilliant Blue• Maraschino cherries, • Gelatin desserts, dairy-based desserts (ice cream and

frozen desserts), • Dry powdered drinks, candy and confectionery

products that are oil and fat free, • Bakery products, cereals, puddings, fruit-based

desserts, • Dried vegetables, fermented vegetable products, • Sugars and table top sugars, • Water-based flavored drinks and snacks, • Fermented milks, cheese, among others

Fast Green

Fast green synthesis is similar to that of brilliant blue benzaldehyde-p-hydroxy-o-sulfonic acid is used instead of benzaldehyde-o-sulfonic acid

Maximum permitted level 100 mg/kg

3-(N-Ethyl-N-(4-((4-(N-ethyl-N-(3-sulfonatobenzyl) amino) phenyl)(4-hydroxy-2- sulfonatophenyl) methylene)-2,5-cyclohexadien-1-ylidineammoniomethyl)- benzensulfonate

Synonyms: C.I. food green 3; FD&C green 3; Ins No. 143; C.I. 42053

Red to brown-violet powder or crystals; soluble in water; slightly soluble in ethanol

Approved in 1982 for food use

Fast green Uses• Fermented milks, fat-based desserts excluding dairy-based

dessert products• Fruit-based spreads, candied fruit, fruit preparations (pulps,

purees, fruit-based desserts, including fruit-flavored water-based desserts, fruit fillings for pastries,

• Confectionery (hard and soft candy), bakery, • Precooked or dried pastas and noodles, cereal and starch-

based desserts (e.g., rice puddings and tapioca pudding)• Fishery products (fish, mollusks, crustaceans, and

echinoderms), fully preserved fishery products (canned or fermented)

• Egg-based desserts, herbs, spices, seasonings (including salt substitutes), emulsified sauces

Indigotine (E132)

• Approved in 1987 for food use• CAS No. 860–22–0• Chemical name(s)– 2-(1,3-Dihydro-3-oxo-5-sulfo-2H-indol-2-ylidine)-2,3-

dihydro-3-oxo-1H-indole-5- sulfuric acid disodium salt 3,3 -′dioxo-(Δ2,2-biindoline)-5,5 -disulfonic acid disodium salt′

• Synonyms – Disodium 5,5 -indigotin disulfonate; ′– sodium indigotin disulfonate; – soluble indigo blue; indigo carmine; acid blue 74; C.I. acid

blue 74; C.I. food blue 1; FD&C blue No. 2; C.I. 73015

Indigotine: Physical data • Dark-blue powder with coppery luster• Sensitive to light; indigotine solutions have a blue or

bluish-purple color• Soluble in water at 25°C, slightly soluble in alcohol,

and insoluble in organic solvents• Always contains sodium chloride or sulfate used for

salting it out• Very sensitive to oxidizing agents• The color is affected by acids and solutions fade on

standing

Indigo Synthesis

Indigotin Synthesis

Indigotine: Uses• Dry powdered drinks, candy and confectionery

products that are oil and fat free• Bakery products, cereals, puddings, dairy-based

desserts (e.g., ice cream, ice milk)• Fruit-based desserts, fruit fillings for pastries, egg-

based desserts (e.g., custard)• Sugars (e.g., white and semi-white, syrups), table top

sweeteners• Water-based flavored drinks, including sport or

electrolyte drinks, snacks (potato, cereal, flour, or starch based), among others

Erythrosine (E127)• Xanthene colorant approved in 1969

– Exhibits brilliant color for yellow or bluing red, as well as fluorescence

– Precursor is fluorescein (one of the earliest synthesized pigments)

• CAS No. 16423–68–0• Chemical name(s)

– 3 ,6 -Dihydroxy-2 ,4 ,5 ,7 -tetraiodospiro(isobenzofuran-′ ′ ′ ′ ′ ′1(3H),9 - 9H) xanthen)-3-one disodium salt′

• Synonyms – 2 ,4 ,5 ,7 -Tetraiodofluorescein disodium salt; ′ ′ ′ ′– Erythrosine BS; erythrosine B; FD&C red No. 3 – C.I. food red 14; C.I. acid red 51; C.I. 45430

Erythrosine: Physical data

• Brown powder; absorption max. (water): 524 nm, in 95% alcohol 531 nm;

• Solubility in water to cherry-red solution; • Hydrochloric acid added to an aqueous

solution produces yellowish-brown precipitate;

• Sodium hydroxide produces a red precipitate

The reaction is carried out in an alkaline solution

Fluorescein is precipitated with acid and then treated with iodine.

The reaction is carried out in a solution of caustic soda that is subjected to electrolysis

Erythrosine synthesis

Erythrosine Uses

• Maraschino cherries, eggs, canned cherries, rhubarb, strawberries, ice cream and frozen desserts,

• Candy and confectionery products that are oil and fat free, bakery products,

• Cereals, puddings, fermented milks, fruit-based spreads, fruit preparations (pulps, purees, fruit toppings, and coconut milks),

• Fishery products (frozen fish, mollusks, crustaceans, and echinoderms),

• Sugars (e.g., white and semi-white, brown sugar, maple sugar), herbs, spices, and seasonings, food supplements,

• Water-based flavoring drinks including sport or electrolyte drinks, snacks (potato, cereal, flour, or starch based), and composite foods (e.g., casseroles, meat pies, mincemeat)

Max level up to 300 mg/kg is permitted

Blends of synthetic colorants

• Certified colors provide different hue colors to industry

• Blue No. 1: Bright yellow• Blue No. 2: Royal blue• Green No. 3: Sea green• Red No. 3: Watermelon red• Red No. 40: Orange red

Blends of Primary Colorants to Produce Specific Shades (parts by weight)

Blends of Primary Colorants to Produce Specific Shades (parts by weight)

Color Stability: pH effect

pH

0 = without appreciable fade; 1 = very slight fade; 2 = slight fade; 3 = appreciable fade; 4 = considerable fade; 5 = fades

Colour Stability in some common food acids

0 = without appreciable fade; 1 = very slight fade; 2 = slight fade; 3 = appreciable fade; 4 = considerable fade; 5 = fades

Colour Stability in the presence of sugars

0 = without appreciable fade; 1 = very slight fade; 2 = slight fade; 3 = appreciable fade; 4 = considerable fade; 5 = fades

Colour Stability in some common food alkalis

0 = without appreciable fade; 1 = very slight fade; 2 = slight fade; 3 = appreciable fade; 4 = considerable fade; 5 = fades

B = bluer; S.B. = slightly bluer; H.B. = highly bluer

Stability in the presence of food additives

0 = without appreciable fade; 1 = very slight fade; 2 = slight fade; 3 = appreciable fade; 4 = considerable fade; 5 = fades

Dye presentation

• Different presentations of dyes are commercially available – powders, liquids, pastes, and dispersions

• Liquid presentations– water, sucrose, glycerin, and propylene

glycol

• Paste colors– made by blending FD&C dyes with

glycerin, propylene glycol, dextrose, and sometimes gums.

• Dispersions in confectionary – mixing the dye with titanium dioxide

Color Bits and Color Wafers International Foodcraft Corporation

Dustmaster 2000 (Warner Jenkinson Company) is a porous granular product that wets and dissolves faster than other granular forms.

Commercial Available Presentations of FD&C Dyes

Commercial Available Presentations of FD&C Dyes

Lakes

Lakes are prepared by extending the FD&C dye on a substratum of alumina in two stages

Hydrate formation

Laking process

Lake is formed by dye precipitation onto the substrate by effect of the addition of the aluminum salt solution.

Hydrate formation is a critical step in the production of lakes, and performanceand quality depends strongly on this stage

Lake particles tend to coalesce to the detriment of product appearance. This problem is minimized by using dispersions

Contrasting Properties of Lakes and Dyes

The current Redbook requirements for toxicological testing [FDA Redbook, cited in IFT

(1986)]:

• One subchronic feeding study, of 90 days duration, in a nonrodent species, usually the dog

• Acute toxicity studies in rats• Chronic feeding studies in at least two animal species

(one with in utero exposure), lasting at least 24–30 months

• One teratology study• One multigeneration reproduction study using mice• One mutagenicity test

Comparative Daily Intake Data for the Certified Colorant Dyes

Hypersensitivity and Hyperactivity

• Tartrazine (FD&C Yellow No. 5) – linked with hypersensitivity in certain individuals (Atopic individuals)

• SunsetYellow FCF (FD&C Yellow No. 6)– proposed for label declaration by the FDA because of putative

hypersensitivity– Opposed by International Association of Color Manufacturers

• Ingestion of certified colorants promoted hyperactivity in children (Fenigold’s hypothesis)– opposed by FDA– a recent doubleblind, placebo-controlled study once again linked

tartrazine ingestion with irritability, restlessness, and sleep disturbances in some children

Colorants Subject to CertificationMonoazo colorants

Azo dyes