Colouring Matters

The use of colouring matter has been acknowledged to play an important role in the consumer acceptability of certain dairy products. However, the need to monitor the compounds used to has been recognized since the early days of the century when cheaper coloured salts of heavy metals were used instead of natural colour. Milk, cream, condensed milk and dried milk are not permitted to contain added colouring matters. However, dairy products viz., cheese, butter, flavoured milk, ice cream are only permitted to contain a restricted number of colours. Specifications for commonly used colourants are given below.

Specification for â-Carotene (Food Grade) as per IS:3841-1966

S. No. Characteristic Requirement

1. Description

It is obtained as dark violet hexagonal prisms when crystallized from benzene-methanol solution; or as red rhombic, almost quadratic plates,from petroleum ether.

2. Melting point, °C 183±1

3. Solubility

Soluble in carbon disulphide, benzene and chloroform; moderately soluble in n-hexane, cyclohexane, petroleum ether and oils; practically insoluble in methanol and ethanol; insoluble in water.

4. Spectrophotometric requirements

The wavelengths of absorption maxima of all trans b-carotene in cyclohexane (0.2 mg per 100 ml) and in 1 cm cell shall be 456 nm to 355 nm region.

(b) A solution of b-carotene in chloroform on addition of antimony trichloride solution shall give a dark blue colour having maximum absorption at a wavelength of 590 nm.

5. Colour reaction

When 2 ml of concentrated sulphuric acid is added to 2 ml of 0.2 percent solution of b-carotene in chloroform, the acid layer shall turn blue.

6. Purity, % by mass 95.0 Min.

7. Arsenic (as As), ppm 5 Max.

8. Lead (as Pb), ppm 20 Max.

Specification for Annatto colour for food products as per IS:2557-1994

S. No. Characteristic Requirement

1. General

The material shall be derived only from the plant Bixa orellana L. and shall not contain any extraneous colouring matter. It shall be processed, packed, stored and distributed under hygienic conditions in licensed premises (IS:2491-1972).

2(a) Solution of Annatto colour in oil

Annatto extract in oil, as solution or suspension, is prepared by extraction of the outer coating of seeds with vegetable oils. Only the vegetable oils included under the Prevention of Food Adulteration Rules, 1955 shall be used, either singly or in a mixture.

(b) The solution of annatto colour in oils shall be clear and shall remain so on storage in suitable containers at 15°C except for a slight deposit of stearin or shall be in the form of a suspension.

2(b) Colour

(a) The colour of solution in amyl acetate at a dilution of 1:1000 (w/v),when measured in a Lovibond Tintometer with a 1 cm cell, shall be not less than 5.o yellow units and 0.4 red units, or

(b) be not less than the colour of the inorganic solution (potassium dichromate-0.32g, cobalt ammonium sulphate (CoSO4.(NH4)SO4.6H2O)-2.02g and sulphuric acid (sp. Gravity 1.84)-2 ml to make solution to 1 litre with distilled water.

3(a) Solution of Annatto colour in water

Water-soluble annatto is prepared by extraction of outer coating of the seeds with dilute (0.5-3%) aqueous alkali (sodium or potassium hydroxide). The solution shall clear and shall be remain so on storage in suitable containers at a temperature of 15°C.

3(b) Colour

The colour of solution in 0.1 N sodium hydroxide or potassium hydroxide at a dilution of 1:1000 (w/v), when measured in a Lovibond Tintometer with a 1 cm cell, shall be not less than 5.0 yellow units and 0.4 red units,

Identification

Spectrophotometry

Annatto extracts in oil, diluted with chloroform exhibit absorbance maxima at 439, 470 and 501 nm. Water-soluble annatto extracts, diluted with water exhibit absorbance maxima at 453 and 482 nm.

Column chromatography and Carr-Price reaction

Prepare a small chromatography column by filling a glass tube (7´mm internal dia.), stoppered with glass wool, with alumina (800-200 mesh) slurried in benzene so that settled alumina fills about 2/3rd of the tube. Fill the column with benzene and adjust the flow rate to about 30 drops/min using a rubber outlet tube and clamp using the benzene layer is 2-3 mm above the alumina surface.

Annatto extract in oil

Add to the top of the alumina column 3 ml of a solution containing sufficient sample in benzene to impart a colour equivalent to a 0.1% potassium dichromate solution; elute with benzene until a pale yellow fraction is washed from the column. Wash the column with three 10 ml volumes of dry chloroform; then add 5 ml of Carr-Price reagent and allow it to run onto the top of the column. The orange-red zone (bixin) at the top of the column immediately becomes blue-green.

Water-soluble annatto

Transfer 2 ml or 2 g to a 50 ml separating funnel and add sufficient 2N sulphuric acid to make the solution acidic in pH paper (pH 1-2). Dissolve the red precipitate of norbixin by mixing the solution with 50 ml of benzene. Discard the water layer and wash the benzene phase with water until it no longer gives an acid reaction. Remove any undissolved norbixin by centrifugation or filtration and dry the solution over anhydrous sodium sulphate. Transfer 3-5 ml of the dry solution to the top of an alumina column prepare as described above. Eluate the column with benzene, three 10 ml volumes of dry chloroform, followed by 5 ml of Carr-Price reagent added to the top of the column. The orange-red band of norbixin immediately becomes blue-green.

Thin layer chromatography

Annatto extract in oil

Use silica gel with 12 percent calcium sulphate as binding agent, and a mixture of acetic acid, chloroform and acetone (1:50:50, by volume) as developing solvent. He sample in oil produces at least 3 or 4 red or yellow spots, Two red spots are clearly more intense than the other spots. Dissolve the two spots in benzene and identify the spot that is bixin by Carr-Price reaction.

Water-soluble annatto

Prepare a chromatogram as described in 9(a). Three or four spots are obtained, of which 2 spots have an orange colour and the others an orange-yellow colour. Dissolve the orange spots in benzene and identify one of he spots that is norbixin by Carr-Price reaction.

Purity(as Carotenoids)

Annatto extract in oil, expressed as bixin, % by mass 0.24 Min.

Water-soluble annatto expressed as norbixin, .% by mass 0.24 Min

6. Arsenic (as As), mg/kg 3 Max.

7. Lead (as Pb), mg/kg 10 Max.

8. Copper (as Cu), mg/kg 30 Max.

9. Heavy metals, mg/kg 40 Max.

Specification for Saffron (Filaments and powder form) as per IS:5453-1996

S. No. Characteristic Requirement

1. Flavour : Flavour shall be characteristic of saffron, slightly bitter and slightly pungent. The product shall be free from foreign flavours.

2. Freedom from moulds, insects, etc. : Saffron shall be free from living insects and shall be practically free from mould growth, dead insects, insect fragments and rodent contamination, visible to naked eye.

Saffron Saffron

(in filaments) (in powder form)

3. Moisture & volatile matter, % by mass 12 Max. 10 Max.

4. Total ash, % by mass 8 Max. 8 Max.

5. Acid insoluble ash, % by mass

(a) Grade 1 & 2 1.0 Max. 1.0 Max.

(b) Grade 3 & 4 1.5 Max. 1.5 Max.

6. Solubility in cold water, % by mass 65 Max. 65 Max.

(on dry basis)

7. Bitterness expressed as direct reading of the absorbance of picrocrocine at 257 nm (on dry basis)

(a) Grade 1 70 Min. 70 Min.

(b) Grade 2 55 Min. 55 Min.

(d) Grade 4 30 Min. 30 Min.

8. Safranal, expressed as direct reading of the absorbance at 330 nm (on dry basis) 20-50 20-50

9. Colouring strength, expressed as direct reading of the absorbance of crocine at 440 nm (on dry basis)

(a) Grade 1 190 Min. 190 Min.

(b) Grade 2 150 Min. 150 Min.

(d) Grade 4 80 Min. 80 Min.

10. Total nitrogen, % by mass (on dry basis) 3.0 Max. 3.0 Max.

11. Crude fibre, % by mass 6 Max. 6 Max.

Specification for Tartrazine (Food Grade) as per IS:1694-1994

S. No. Characteristic Requirement

1. Freedom from contaminants: Material shall be free from mercury,copper and chromium in any form: aromatic amines, aromatic nitro compounds, aromatic hydrocarbons and cyanides.

2. Total dye, % by mass (on dry at 105±1°C for 2h basis) 87 Min.

3. Loss on drying at 135°C, % by mass and Chlorides & sulphates

(as sodium salt), % by mass 13 Max.

4. Water-insoluble matter, % by mass 0.2 Max.

5. Combined ether extracts, % by mass 0.2 Max.

6. Subsidiary dyes, % by mass 1.0 Max.

7. Dye intermediates, % by mass 0.5 Max.

8. Lead (as Pb), mg/kg 10 Max.

9. Arsenic (as As), mg/kg 3 Max.

10. Heavy metals, mg/kg 40 Max.

Specification for Carmoisine (Food Grade) as per IS:2923-1995

S. No. Characteristic Requirement

1. Freedom from contaminants: Material shall be free from mercury,selenium and chromium in any form: aromatic amines, aromatic nitro compounds, aromatic hydrocarbons and cyanides.

2. Total dye, % by mass (on dry at 105±1°C for 2h basis) 87 Min.

3. Loss on drying at 135°C, % by mass and Chlorides & sulphates

(as sodium salt), % by mass 13 Max.

4. Water-insoluble matter, % by mass 0.2 Max.

5. Combined ether extracts, % by mass 0.2 Max.

6. Subsidiary dyes, % by mass 1.0 Max.

7. Dye intermediates, % by mass 0.5 Max.

8. Lead (as Pb), mg/kg 10 Max.

9. Arsenic (as As), mg/kg 3 Max.

10. Heavy metals, mg/kg 40 Max.

Specification for Sunset yellow (Food Grade) as per IS:1695-1994

S. No. Characteristic Requirement

1. Freedom from contaminants: Material shall be free from mercury, copper and chromium in any form: aromatic amines, aromatic nitro compounds, aromatic hydrocarbons and cyanides.

2. Total dye, % by mass (on dry at 105±1°C for 2h basis) 87 Min.

3. Loss on drying at 135°C, % by mass and Chlorides & sulphates

(as sodium salt), % by mass 13 Max.

4. Water-insoluble matter, % by mass 0.2 Max.

5. Combined ether extracts, % by mass 0.2 Max.

6. Subsidiary dyes (lower sulphonated dyes including 3.0 Max.

traces of orange II), % by mass

7. Dye intermediates, % by mass 0.5 Max.

8. Lead (as Pb), mg/kg 10 Max.

9. Arsenic (as As), mg/kg 3 Max.

10. Heavy metals, mg/kg 40 Max.

Specification for Ponceau 4R (Food Grade) as per IS:2558-1994

S. No. Characteristic Requirement

1. Freedom from contaminants: Material shall be free from mercury,selenium and chromium in any form: aromatic amines, aromatic nitro compounds, aromatic hydrocarbons and cyanides.

2. Total dye, % by mass (on dry at 105±1°C for 2h basis) 82 Min.

3. Loss on drying at 135°C, % by mass andChlorides & sulphates

(as sodium salt), % by mass 18 Max.

4. Water-insoluble matter, % by mass 0.4 Max.

5. Combined ether extracts, % by mass 0.4 Max.

6. Subsidiary dyes, % by mass 1.0 Max.

7. Dye intermediates, % by mass 0.5 Max.

8. Lead (as Pb), mg/kg 10 Max.

9. Arsenic (as As), mg/kg 3 Max.

10. Heavy metals, mg/kg 40 Max.

Specification for Brilliant blue FCF (Food Grade) as per IS:6406-1994

S.No.Characteristic Requirement

1. Total dye, % by mass (on dry at 105±1°C for 2h basis) 85 Min.

2. Loss on drying at 135°C, % by mass and Chlorides & sulphates

(as sodium salt), % by mass 15 Max.

3. Water-insoluble matter, % by mass 0.2 Max.

4. Combined ether extracts, % by mass 0.2 Max.

5. Subsidiary dyes, % by mass 3.0 Max.

6. Dye intermediates, % by mass

(a) O-sulpho-benzaldehyde 1.5 Max.

(b) N,N’ ethyl-benzyl-aniline-3-sulphonic acid 0.3 Max.

7. Lead (as Pb), mg/kg 10 Max.

8. Arsenic (as As), mg/kg 3 Max.

9. Heavy metals, mg/kg 50 Max.

Specification for Ponceau 4R (Food Grade) as per IS:2558-1994

S. No. Characteristic Requirement

1. Freedom from contaminants: Material shall be free from mercury,selenium and chromium in any form: aromatic amines, aromatic nitro compounds, aromatic hydrocarbons and cyanides.

2. Total dye, % by mass (on dry at 105±1°C for 2h basis) 82 Min.

3. Loss on drying at 135°C, % by mass and Chlorides & sulphates

(as sodium salt), % by mass 18 Max.

4. Water-insoluble matter, % by mass 0.4 Max.

5. Combined ether extracts, % by mass 0.4 Max.

6. Subsidiary dyes, % by mass 1.0 Max.

7. Dye intermediates, % by mass 0.5 Max.

8. Lead (as Pb), mg/kg 10 Max.

9. Arsenic (as As), mg/kg 3 Max.

10. Heavy metals, mg/kg 40 Max.

Specification for Brilliant blue FCF (Food Grade) as per IS:6406-1994

S. No. Characteristic Requirement

1. Total dye, % by mass (on dry at 105±1°C for 2h basis) 85 Min.

2. Loss on drying at 135°C, % by mass and Chlorides & sulphates

(as sodium salt), % by mass 15 Max.

3. Water-insoluble matter, % by mass 0.2 Max.

4. Combined ether extracts, % by mass 0.2 Max.

5. Subsidiary dyes, % by mass 3.0 Max.

6. Dye intermediates, % by mass

(a) O-sulpho-benzaldehyde 1.5 Max.

(b) N,N’ ethyl-benzyl-aniline-3-sulphonic acid 0.3 Max.

7. Lead (as Pb), mg/kg 10 Max.

8. Arsenic (as As), mg/kg 3 Max.

9. Heavy metals, mg/kg 50 Max.

Specification for Fast Green FCF (Food Grade) as per IS:6022-1994

S. No. Characteristic Requirement

1. Freedom from contaminants: Material shall be free from aromatic amines, aromatic nitro compounds, aromatic hydrocarbons and cyanides.

2. Total dye, % by mass (on dry at 105±1°C for 2h basis) 85 Min.

3. Loss on drying at 135°C, % by mass and Chlorides & sulphates

(as sodium salt), % by mass 13 Max.

4. Water-insoluble matter, % by mass 0.2 Max.

5. Combined ether extracts, % by mass 0.2 Max.

6. Subsidiary dyes, % by mass 1.0 Max.

7. Organic compounds other than colouring matter, uncombined intermediates and products of side reactions:

(a) Sum of 2-, 3-, 4-formyl benzene sulphonic acid, 0.5 Max.

sodium salt, % by mass

(b) Sum of 3- and 4-[ethyl (4-sulfophenyl) amino] 0.3 Max.

methyl benzene sulphonic acid, disodium salt,% by mass

sodium salt, % by mass

(d) Leuco base, % by mass 5.0 Max.

(e) Unsulphated primary aromatic amines 0.01 Max.

(as aniline), % by mass

8. Lead (as Pb), mg/kg 10 Max.

9. Arsenic (as As), mg/kg 3 Max.

10. Chromium (as Cr), mg/kg 50 Max.

11. Mercury (as Hg), mg/kg Absent

12. Heavy metals, mg/kg 40 Max.

Specification for Indigo carmine (Food Grade) as per IS:1698-1994

S. No. Characteristic Requirement

1. Freedom from contaminants: Material shall be free from mercury, copper and chromium in any form: aromatic amines, aromatic nitro compounds, aromatic hydrocarbons and cyanides.

2. Total dye, % by mass (on dry at 105±1°C for 2h basis) 85 Min.

3. Loss on drying at 135°C, % by mass and Chlorides & sulphates

(as sodium salt), % by mass 15 Max.

4. Water-insoluble matter, % by mass 0.4 Max.

5. Combined ether extracts, % by mass 0.4 Max.

6. Subsidiary dyes, % by mass 3.0 Max.

7. Isatin sulphonic acid, % by mass 1.0 Max.

8. Lead (as Pb), mg/kg 10 Max.

9. Arsenic (as As), mg/kg 3 Max.

10. Heavy metals, mg/kg 40 Max.

Specification for Amaranth (Food Grade) as per IS:1696-1994

S. No. Characteristic Requirement

1. Freedom from contaminants: Material shall be free from mercury, selenium and chromium in any form: aromatic amines, aromatic nitro compounds, aromatic hydrocarbons and cyanides.

2. Total dye, % by mass (on dry at 105±1°C for 2h basis) 85 Min.

3. Loss on drying at 135°C, % by mass and

Chlorides & sulphates (as sodium salt), % by mass 15 Max.

4. Water-insoluble matter, % by mass 0.5 Max.

5. Combined ether extracts, % by mass 0.2 Max.

6. Subsidiary dyes, % by mass 4.0 Max.

7. Dye intermediates, % by mass 0.5 Max.

8. Lead (as Pb), mg/kg 10 Max.

9. Arsenic (as As), mg/kg 3 Max.

10. Heavy metals, mg/kg 40 Max.

Pages

Dairy Technology