Food Additive Testing Methods

Author: Chief Editor: Li Yibing et al
Publisher:
Publish Date: 2000-01-01
Features:
Fragment:
1. Characteristics The product is colorless to white crystals, a white crystalline powder, or a white powder with an extremely sweet taste, even in a 10,000-fold aqueous solution.①
2. Identification Test
(1) Take 0.5g of the product, add 10mL of water, and add 1mL of dilute hydrochloric acid. Allow to stand for 1h, filter the white crystalline precipitate formed, wash it thoroughly with water, and dry at 105℃ for 2h. The melting point is 226–230℃.②
(2) Take 20mg of the product and 40mg of resorcinol, add 10 drops of sulfuric acid, and let it stand. When the mixture turns deep green upon heating, cool it, then add 10mL of water and 10mL of sodium hydroxide test solution to dissolve. The solution emits green fluorescence.③
(3) Dissolve 0.1g of the product in 5mL of sodium hydroxide test solution, let it stand, heat, and evaporate to dryness, avoiding carbonization. Carefully melt it until no ammonia odor is emitted, then cool. Dissolve the residue in about 20mL of water, neutralize with dilute hydrochloric acid, and filter. When 1 drop of ferric chloride test solution is added to the filtrate, it turns purple to red-purple.④
(4) The residue obtained after ashing the product shows the conventional identification reactions of sodium salts.
3. Purity Test
(1) Solubility After crushing the product, dissolve 1g in 1.5mL of water and 70mL of ethanol. The solutions should be colorless and clear.⑤
(2) Free Acid and Free Alkali Dissolve 1g of the product in 10mL of water that has been boiled and cooled. Add 1 drop of phenolphthalein test solution; it should not turn red. Then add 1 drop of 0.1mol/L sodium hydroxide solution, and it should turn red.
(3) Benzoate and Salicylate Take 0.5g of the product, add 10mL of water, and add 5 drops of acetic acid and 3 drops of ferric chloride test solution. No precipitate should form, and it should not turn purple to red-purple.⑥
(4) Arsenic Take 2.5g of the product, place it in a decomposition flask, add 10mL of nitric acid and 5mL of sulfuric acid, and heat. Cool when the liquid is still brown, add 1mL of nitric acid, and heat again. Repeat this operation until the liquid turns colorless to pale yellow, then heat until white fumes are emitted. After cooling, add 10mL of water and 15mL of saturated ammonium oxalate solution, and heat until white fumes are emitted again. After cooling, add water to make up to 25mL, take 5mL as the test solution, and perform the conventional arsenic test. The result should meet the procedure described. However, the standard color is obtained by adding 5mL of arsenic standard solution to the decomposition flask, adding 10mL of nitric acid, and performing the same operations as the sample.
(5) Heavy Metals Take 1g of the product, add 45mL of water and 2mL of acetic acid, and perform the conventional heavy metal test. The amount should be less than 0.0005%.
(6) Sulfuric Acid Color Test Take 0.2g of the product, add 5mL of sulfuric acid, mix thoroughly, and heat at 48–50℃ for 10min. The color of the solution should not be deeper than the color of standard solution A.⑦