Chemical Preservatives

Chemical preservatives are those food additives, which are specifically added to prevent the deterioration or decomposition of a food. These deteriorations may be caused by microorganisms, by food enzymes, or by purely chemical reactions.Preservatives may be used as antioxidants to hinder the oxidation of unsaturated fats, as neutralizers of acidity, as stabilizers to prevent physical changes, as firming agents, and as coatings or wrappers to keep out microorganisms, prevent loss of water, or hinder undesirable microbial, enzymatic, and chemical reactions. The federal Food, Drug and Cosmetic Act defines a chemical preservatives as any chemical which, when added to food, tends to prevent or retard deterioration thereof; but does not include common salt, sugars, vinegars, spices, or oils extracted from spices or substances added by smoke.

Specification for Sorbic acid (Food grade) as per IS:4818-1996

1.Description: It is slightly soluble in water and soluble in ethanol.

2. Identification

Melting range: The melting range of the material shall be 132°C to 135°C.When to 1 ml of saturated solution of bromine in water, 0.02 g of the material is added and shaken well, the colour shall disappear.

3. Purity (as C6H8O2), % by mass 99.0 Min.

4. Moisture, % by mass 0.5 Max.

5. Sulphated ash, % by mass 0.2 Max.

6. Aldehydes, % by mass 0.1 Max.

7. Stability To conform to test

8. Arsenic (as As), mg/kg 3.0 Max.

9. Heavy metals (as Pb), mg/kg 10 Max.

Specification for Sodium benzoate (Food grade) as per IS:4447-1994

1.Description: Sodium benzoate is a white, almost odourless, crystalline powder or flakes. It is freely soluble in water and sparingly soluble in 95% ethanol.

2. Identification

Reaction with ferric chloride: When ferric chloride solution is added to a 10 % solution of sodium benzoate in water, a buff precipitate shall be formed.

Reaction with uranyl zinc acetate: The material shall give a yellow crystalline precipitate with uranyl zinc acetate.

Flame test: The material shall give a distinct golden-yellow flame.

Melting range of precipitate with hydrochloric acid: The melting range of precipitate obtained with hydrochloric acid shall be between 121.5°C to 123.5°C.

3. Purity (as C7H5O2N), % by mass 99.0 Min.

4. Moisture, % by mass 1.5 Max.

5. Acidity or alkalinity To conform to test

6. Readily carbinizable substances To conform to test

7. Readily oxidizable substances To conform to test

8. Chlorinated organic compounds To conform to test

9. Arsenic (as As), mg/kg 3.0 Max.

10. Heavy metals (as Pb), mg/kg 10 Max.

Specification for Sodium benzoate (Food grade) as per IS:4447-1994

1.Description: Sodium benzoate is a white, almost odourless, crystalline powder or flakes. It is freely soluble in water and sparingly soluble in 95% ethanol.

2. Identification

Reaction with ferric chloride: When ferric chloride solution is added to a 10 % solution of sodium benzoate in water, a buff precipitate shall be formed.

Reaction with uranyl zinc acetate: The material shall give a yellow crystalline precipitate with uranyl zinc acetate.

Flame test: The material shall give a distinct golden-yellow flame.

Melting range of precipitate with hydrochloric acid: The melting range of precipitate obtained with hydrochloric acid shall be between 121.5°C to 123.5°C.

3. Purity (as C7H5O2N), % by mass 99.0 Min.

4. Moisture, % by mass 1.5 Max.

5. Acidity or alkalinity To conform to test

6. Readily carbinizable substances To conform to test

7. Readily oxidizable substances To conform to test

8. Chlorinated organic compounds To conform to test

9. Arsenic (as As), mg/kg 3.0 Max.

10. Heavy metals (as Pb), mg/kg 10 Max.

Specification for Sodium propionate (Food grade) as per IS:6030-1997

1.Description: Sodium propionate shall be colourless and in the form of transparent crystals or a granular crystalline powder. It shall be odourless or has a faint acetic butyric odour. It shall be deliquescent in moist air and freely soluble in water and soluble in ethanol.

2. Identification

Five percent solution of material gives positive test for sodium. A solution of sodium propionate acidified with dilute acetic acid, filtered, if necessary,and treated with uranyl zinc acetate, shall yield a yellow crystalline precipitate, indicating the presence of sodium.Upon ignition, the material shall yield an alkaline residue, which effervesces with acids.Warm a small sample with sulphuric acid. Propionic acid evolved shall be recognized by its odour.The pH of 10 % m/v solution of the material at 25±2°C shall be between 7.5 and 10.

3. Purity (as C3H5O2Na), % by mass (on dry basis) 99.0 Min.

4. Moisture, % by mass 1 Max.

5. Matter insoluble in water, % by mass 0.1 Max.

6. Arsenic (as As), mg/kg 3.0 Max.

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

8. Iron (as Fe), mg/kg 30 Max.

9. Lead (as Pb), mg/kg 5 Max.

10. Fluoride (as F), mg/kg 10 Max.

Specification for Calcium propionate (Food grade) as per IS:6031-1997

1.Description: It shall be in the form of white crystals or crystalline solid or possessing a faint odour of propionic acid. The material shall be freely soluble in water.

2. Identification

Five percent solution of material gives positive test for calcium. He presence of calcium may be demonstrated by reacting a solution of calcium propionate with ammonium oxalate solution. The white precipitate formed is soluble in hydrochloric acid, but insoluble in acetic acid.Upon ignition at a relatively low temperature, it yields an alkaline residue which effervesces with acids.Warm a small sample with sulphuric acid. Propionic acid evolved shall be recognized by its odour.The pH of 10 % m/v solution of the material at 25±2°C shall be between 7 and 9.

3. Purity (as C6H10O4Ca), % by mass (on dry basis) 98.0 Min.

4. Moisture, % by mass 5.0 Max.

5. Matter insoluble in water, % by mass 0.3 Max.

6. Arsenic (as As), mg/kg 3.0 Max.

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

8. Iron (as Fe), mg/kg 30 Max.

9. Lead (as Pb), mg/kg 5 Max.

10. Fluoride (as F), mg/kg 10 Max.

11. Magnesium (as MgO), % by mass 0.4 Max. (To pass the test)

Specification for Sodium metabisulphite (Food grade) as per IS:4752-1994

1.Description: The material shall be colourless crystals or white to yellowish crystalline powder having an odour of sulphur dioxide. The material is soluble in water but insoluble in ethanol.

2. Identification

Aqueous solution of the material shall be acidic to a solution of phenol red.Aqueous solution of the material shall decolourize a solution of iodine give positive.Ten percent solution of the material shall give positive test for sodium.

Test for sodium: When uranyl zinc acetate is added to the solution yellow crystalline precipitate shall be formed with several minutes’ agitation.

Test for sulphite: When dilute sulphuric acid is added to the solution,sulphur dioxide shall be produced which may be recognized by its characteristic odour, or by blackening of filter paper moistened with

mercurous nitrate or by the development of a blue colour on filter paper treated with potassium iodate and starch.

3. Water insolubles: Twenty grams of the material when dissolved in 200 ml of water shall give a clear with only a trace of suspended matter.

4. Purity

(a) as Na2S2O3, % by mass 95 Min.

(b) as SO2, % by mass 64 Min.

5. Moisture, % by mass 1 Max.

6. Matter insoluble in water, % by mass 0.05 Max.

7. Thiosulphate, % by mass 0.1 Max.

8. Arsenic (as As), mg/kg 3.0 Max.

9. Heavy metals (as Pb), mg/kg 10 Max.

10. Iron (as Fe), mg/kg 5 Max.

11. Selenium (as Se), mg/kg 5 Max.

12. Lead (as Pb), mg/kg 2 Max.

13. pH Acidic to litmus

Specification for Potassium nitrate (Food grade) as per IS:4753-1996

1.Description: Potassium nitrate shall be colourless, transparent prisms, or white granules or a crystalline powder. It shall be odourless and shall have a salty taste. It shall produce a cooling sensation in the mouth. It shall be slightly hygroscopic in moist air. The material is soluble in water and slightly soluble in ethanol and glycerol.

2. Identification

Aqueous solution of the material shall be neutral to litmus.Ten percent solution of the material shall give positive test for potassium.

Test for potassium: When to a neutral 10 % solution of the material sodium bitartrate is added, a white precipitate shall be formed. This precipitate shall be soluble in ammonia and in solutions of alkali hydroxide or carbonates.

Test for nitrate: When the solution is mixed with a n equal volume of sulphuric acid, the mixture cooled, and a solution of ferrous sulphate superimposed, a brown colour shall be produced at the junction of the two liquids.When the solution is heated with sulphuric acid and metallic copper,brownish red fumes shall be evolved.The solution shall not decolourize acidified potassium permanganate solution (distinction from nitrites).

3. Purity as KNO3, % by mass 99 Min.

4. Moisture, % by mass 1 Max.

5. Matter insoluble in water, % by mass To pass the test

6. Chlorate To pass the test

7. Arsenic (as As), mg/kg 3.0 Max.

8. Sulphates (as K2SO4), % by mass 0.1 Max.

9. Heavy metals (as Pb), mg/kg 20 Max.

10. Nitrite, mg/kg 1000 Max.