GB 1886.375-2024National food safety standard - Food additive - Calcium hydroxide (English PDF)

1 Scope

GB 1886.375-2024 is the Chinese mandatory food safety standard for calcium hydroxide used as a food additive. Slaked lime is an old and heavily used processing aid: it nixtamalises maize, it regulates acidity, it firms fruit and vegetable tissue, it clarifies sugar juice, and it is consumed in quantity, which is why its identity and purity are fixed by a mandatory standard rather than left to trade practice. The standard applies to calcium hydroxide produced by slaking calcium oxide and to material obtained by the other route the text recognises. It gives the chemical name, molecular formula and relative molecular mass, then the technical requirements, the sensory description and the physicochemical criteria, assay, loss on ignition, acid-insoluble matter, magnesium and alkali salts, fluoride, and the limits on arsenic, lead and other heavy metals that matter for a mineral additive made from a quarried raw material. An appendix carrying most of the document gives the full test method for each of those criteria, with the reagents, apparatus, procedure and calculation. It was issued by the National Health Commission and the State Administration for Market Regulation and took effect on 8 August 2024.

This standard applies to the food additive calcium hydroxide, which is made by digesting calcium oxide as raw material, OR the food additive calcium hydroxide, which is made by calcining limestone or oyster as raw material into calcium oxide and then digesting it.

3 Technical requirements

3.1 Sensory requirements Sensory requirements shall comply with the provisions of Table 1.

3.2 Physical and chemical indicators The physical and chemical indicators shall comply with the provisions of Table 2.

Appendix A

Testing method A.1 Warning Some reagents used in the test methods of this standard are toxic or corrosive and shall be handled with caution. If necessary, it shall be carried out in a fume hood. If it splashes on the skin or eyes, rinse immediately with plenty of water. In serious cases, seek immediate treatment. A.2 General provisions The reagents and water used in this standard, unless other requirements are noted, refer to analytically pure reagents and grade three water specified in GB/T 6682. The standard titration solutions, standard solutions for impurity determination, preparations and products used in the test shall be prepared, in accordance with the provisions of GB/T 601, GB/T 602, GB/T 603, unless other requirements are specified. The solutions used refer to aqueous solutions unless the solvent used to prepare them is specified. A.3 Identification test A.3.1 Reagents and materials A.3.1.1 Hydrochloric acid. A.3.1.2 Acetic acid solution: 1 + 1. A.3.1.3 Ammonium oxalate solution: 40 g/L; weigh 4 g of ammonium oxalate (C2H8N2O4·H2O) and dissolve it in 100 mL of water. A.3.1.4 Red litmus paper. A.3.2 Identification method A.3.2.1 Identification of hydroxyl radicals Weigh about

5.0 g of the specimen. Place it in a beaker. Add 20 mL of water and mix. The specimen will form a thick paste. The clear liquid on the upper layer of the thick paste will turn the red litmus paper blue. A.3.2.2 Identification of calcium ions Weigh about 1 g of the specimen. Place it in a beaker. Add 20 mL of water to mix. Add enough acetic acid solution to dissolve the specimen. Then add ammonium oxalate solution to generate insoluble oxalate precipitate. This precipitate is insoluble in acetic acid but soluble in hydrochloric acid. absolute difference between two independent determination results, as obtained under repeatability conditions, is not greater than 0.03%. A.6 Determination of acid-insoluble matter A.6.1 Reagents and materials A.6.1.1 Hydrochloric acid solution: 1 + 3. A.6.1.2 Silver nitrate solution: 17 g/L. A.6.2 Instruments and equipment A.6.2.1 Glass sand crucible: Pore size 5 µm ~ 15 µm. A.6.2.2 Electric constant temperature drying oven: The temperature control range is 105 °C ± 2 °C. A.6.3 Analytical procedures Weigh about 4 g of the specimen, accurate to 0.0002 g. Place it in a beaker. Add a small amount of water to moisten it. Add 60 mL of hydrochloric acid solution. Heat and boil after the specimen is dissolved. Transfer while hot to a glass sand crucible that has been dried at 105 °C ± 2 °C to a constant mass. Carry out suction filter. Use hot water to wash the filtrate, until there is no chloride ion (check with silver nitrate solution). Place the glass sand crucible together with the acid-insoluble matter in an electric constant temperature drying oven. Dry it at 105 °C ± 2 °C for

1.5 hours. Take it out. Place it in a desiccator. Weigh it after 30 minutes. Then place it in an electric constant temperature drying oven, to dry for 30 minutes. Repeat the above operation, until the difference between the last two weighing results is no more than 0.0003 g. A.6.4 Result calculation The mass fraction w3 of acid-insoluble matter is calculated according to formula (A.3). Where: m4 - The mass of the glass sand crucible and acid-insoluble matter after drying, in grams (g); m5 - The mass of the glass sand crucible, in grams (g); m6 - The mass of the specimen, in grams (g). The test results are based on the arithmetic mean of parallel measurement results. The absolute difference between two independent determination results, as obtained under repeatability conditions, is not greater than 0.03%. A.7 Determination of carbonate A.7.1 Reagents and materials Hydrochloric acid solution: 1 + 3. A.7.2 Analytical procedures Weigh about 2 g of specimen, accurate to

0.01 g. Place it in a beaker. Add 50 mL of water. Mix well. Add 40 mL of hydrochloric acid solution. Only slight bubbles shall be generated during the dissolution process. A.8 Determination of magnesium and alkali metals A.8.1 Reagents and materials A.8.1.1 Sulfuric acid. A.8.1.2 Hydrochloric acid solution: 1 + 3. A.8.1.3 Ammonia solution: 1 + 1. A.8.1.4 Oxalic acid solution: 63 g/L. Weigh

6.3 g of oxalic acid (C2H2O4·2H2O) and dissolve it in 100 mL water. A.8.1.5 Methyl red indicator solution: 1 g/L. A.8.2 Instruments and equipment High temperature furnace: Temperature control range is 800 °C ± 25 °C. A.8.3 Analytical procedures Weigh about

0.5 g of the specimen, accurate to 0.0002 g. Place it in a beaker. Add 10 mL of water and about 6 mL of hydrochloric acid solution. Stir until the specimen is completely dissolved. Boil for 1 min. Quickly add 40 mL of oxalic acid solution and stir. Add 2 drops of methyl red indicator solution. Add ammonia solution dropwise, until the solution turns yellow. After cooling, transfer the mixture to a 100 mL volumetric flask. Use water to dilute it to the mark. Shake well. Let it stand for 4 hours or overnight. Use medium-speed filter paper to make dry filtration. Discard 10 mL of the initial solution. Use a pipette to transfer 50 mL of the filtrate into a crucible, that has been preheated at 800 °C ± 25 °C to a constant mass. Add

0.5 mL of sulfuric acid. Evaporate to near dryness in a water bath (or evaporate to near dryness on an electric furnace at low temperature). Then carefully evaporate to dryness on the electric stove. Continue heating to completely decompose and volatilize the ammonium salt. Take it A.9.2 Analytical procedures A.9.2.1 Preparation of standard turbidity solution Pipette

3.00 mL of barium standard solution. Place it in a 50 mL colorimetric tube. Add water to 25 mL. Add 15 mL of acetic acid-sodium acetate buffer solution (pH~4.5),

0.5 mL of potassium chromate solution. Use water to dilute it to the mark. Shake well. Place for 15 minutes. A.9.2.2 Test Weigh

0.01 g of specimen. Place it in a beaker. Add 10 mL of water to moisten it. Add 20 mL of hydrochloric acid solution to dissolve the specimen. Use slow filter paper to make filtration. Place the filtrate in a 50 mL volumetric flask. Use water to dilute to the mark. Shake well. Use a pipette to remove 25 mL of filtrate. Place it in a 50 mL colorimetric tube. Add 15 mL of acetic acid-sodium acetate buffer solution (pH ~4.5) and

0.5 mL of potassium chromate solution. Use water to dilute to the mark. Shake well. Let it stand for 15 minutes. Compare the turbidity with the standard turbidity solution processed at the same time. The turbidity of the specimen is not deeper than that of the standard turbidity solution, that is, the barium content is not more than 0.03%. A.10 Determination of lead (Pb) Measure according to the method specified in GB 5009.75 or GB 5009.12. The water used in the test is grade 2 water specified in GB/T 6682. A.11 Determination of total arsenic (calculated as As) Measure according to the method specified in GB 5009.76 or GB 5009.11. The water used in the test is grade 2 water specified in GB/T 6682. A.12 Determination of sieve residue A.12.1 Instruments and equipment A.12.1.1 Test sieve: Sieve frame size phi200 mm × 50 mm; basic mesh size

0.045 mm; metal wire (austenitic stainless steel) diameter