CITRIC ACID

Prepared at the 53rd JECFA (1999) and published in FNP 52 Add 7 (1999), superseding specifications prepared at the 51st JECFA (1998), published in FNP 52 Add 6 (1998). Group ADI "Not limited" for citric acid and its calcium, potassium, sodium and ammonium salts established at the 17th JECFA in 1973.

SYNONYMS

INS No. 330

DEFINITION

Citric acid may be produced by recovery from sources such as lemon or pineapple juice or fermentation of carbohydrate solutions or other suitable media using Candida spp. or non-toxicogenic strains of Aspergillus niger

Chemical names

2-hydroxy-1,2,3-propanetricarboxylic acid

C.A.S. number

77-92-9 (anhydrous)

5949-29-1 (monohydrate)

Chemical formula

C₆ H₈ O₇ (anhydrous)

C₆ H₈ O₇ · H₂ O (monohydrate)

Structural formula

Anhydrous                            Monohydrate

Formula weight

192.13 (anhydrous)

210.14 (monohydrate)

Assay

Not less than 99.5% and not more than 100.5% on the anhydrous basis

DESCRIPTION

White or colourless, odourless, crystalline solid; the monohydrate form effloresces in dry air

FUNCTIONAL USES

Acidulant; sequestrant; synergist for antioxidants; flavouring agent (see "Flavouring agents" monograph)

CHARACTERISTICS

IDENTIFICATION

Solubility (FNP 5)

Very soluble in water; freely soluble in ethanol; slightly soluble in ether

Test for citrate (FNP 5)

Passes test

PURITY

Water (FNP 5)

Anhydrous: Not more than 0.5% (Karl Fischer Method)

Monohydrate: Not less than 7.5% and not more than 8.8% (Karl Fischer Method)

Sulfated ash (FNP 5)

Not more than 0.05%

Oxalate (FNP 5)

Not more than 100 mg/kg

Test 1.0 g of the sample by the Oxalate Limit Test (FNP 5). Measure absorbance at 520 nm in a 10 mm cell. The test solution should have less than 0.023 absorbance units.

Sulfates (FNP 5)

Not more than 150 mg/kg

Test 20 g of the sample by the Sulfates Limit Test (FNP 5) using 6.0 ml of 0.01N sulfuric acid in the standard

Readily carbonizable substances

Heat 1.0 g of sample with 10 ml of 98% sulfuric acid in a water bath at 90±1^o for 60 min. No colour darker than MatchingFluid K (25^o) should be produced (not more than 0.5 absorbance units at 470 nm in a 10 mm cell).

Lead (FNP 5)

Not more than 0.5 mg/kg

Prepare a sample solution as directed for organic compounds in the Limit Test and determine by atomic absorption spectroscopy (FNP 5)

METHOD OF ASSAY

Weigh, to the nearest mg, 2.5 g of the sample and place in a tared flask. Dissolve in 40 ml of water and titrate with 1 N sodium hydroxide, using phenolphthalein TS as the indicator. Each ml of 1 N sodium hydroxide is equivalent to 64.04 mg of C₆H₈O₇.