Refining method of food-grade ammonium chloride

Abstract

The invention discloses a refining method of food-grade ammonium chloride. The refining method comprises the following steps: (1) dissolving industrial-grade ammonium chloride into a saturated solution at 70-90 DEG C; (2) adding 0.5-2% of food-grade activated carbon (activated by phosphoric acid, and the specific surface area is greater than or equal to 1000m < 2 > / g), and adsorbing at 75-85 DEG C for 1-2 hours; (3) cooling to 40-50 DEG C, and filtering with a microfiltration membrane (ceramic or PVDF membrane) of 0.22-0.45 [mu] m; (4) cooling the filtrate to 10-20 DEG C at a speed of 0.5-1.5 DEG C / min, and adding 0.01-0.05% of seed crystal (100-150 [mu] m) to induce crystallization; and (5) carrying out centrifugal separation, leaching with ice deionized water, and carrying out vacuum drying at 50-60 DEG C. The purity of the obtained product is more than or equal to 99.5%, the lead content is less than or equal to 1ppm, the arsenic content is less than or equal to 0.5 ppm, the sulfate content is less than or equal to 30ppm, and the water insoluble substance content is According to the method disclosed by the invention, the defects of high impurity residue and crystal wrapping in the traditional process are overcome by combining activated carbon-membrane filtration synergistic deep impurity removal and seed crystal temperature control crystallization, and the method is suitable for baking a dough regulator (0.1-0.3 wt%) and fermenting a yeast nutritional agent (0.05-0.15 wt%).

Description

Technical Field

[0001] The present invention belongs to the field of fine chemical separation technology, and specifically relates to a method for refining food-grade ammonium chloride. By synergizing activated carbon adsorption, precision membrane filtration and a controllable crystallization process, heavy metals, sulfates and colloidal impurities are efficiently removed, thereby meeting the high purity and hygienic safety standards of food additives. Background Art

[0002] Food-grade ammonium chloride is an important food additive. It acts as a dough conditioner in the baking industry to improve ductility, and as a nitrogen source in fermented beverages to promote yeast activity. Its core quality indicators far exceed those of industrial-grade products, especially with strict restrictions on heavy metals (Pb, As), sulfates, and water-insoluble matter (such as Pb ≤ 2ppm). Traditional refining processes have two bottlenecks: one is insufficient impurity removal efficiency - although the recrystallization method can reduce some impurities, the removal rate of trace heavy metals and organic pigments is low, and repeated purification is required, resulting in a sharp drop in yield; the second is hygiene control defects - activated carbon relies on plate and frame filtration after adsorption, with low interception efficiency and easy introduction of fiber contamination, making it difficult to meet food-grade cleanliness requirements.

[0003] Current technology approaches have significant limitations: While ion exchange can deeply remove impurities, resin regeneration produces high-salt wastewater, which is inconsistent with green production trends; solvent crystallization requires the use of toxic organic solvents (such as methanol), which carries the risk of residual residues; and conventional membrane separation technology, which lacks synergy with adsorption processes, is prone to membrane fouling when exposed to colloidal impurities. Furthermore, existing processes lack precise control over the crystallization process, resulting in crystals encapsulated with impurities or uneven particle size, affecting product solubility.

[0004] Therefore, there is an urgent need to develop an efficient, green and industrializable method for refining ammonium chloride, which can achieve deep removal of heavy metals, efficient retention of sulfate and controllable crystal morphology while ensuring food-grade hygiene and safety, so as to meet the quality requirements of high-end food additives. Summary of the Invention

[0005] In view of the above problems, the present invention discloses a method for refining food-grade ammonium chloride.

[0006] The purpose of the present invention is achieved through the following technical solutions.

[0007] A method for refining food-grade ammonium chloride comprises the following steps:

[0008] (1) Dissolution: Add industrial-grade ammonium chloride raw material to deionized water, stir and dissolve at 70-90°C until saturated, to obtain a saturated ammonium chloride solution;

[0009] (2) Activated carbon adsorption: Add activated carbon to the saturated solution obtained in step (1), the amount of activated carbon added is 0.5-2% of the mass of the ammonium chloride raw material, and stir and adsorb at 75-85°C for 1-2 hours;

[0010] (3) Precision membrane filtration: Cool the solution after treatment in step (2) to 40-50°C and filter it using a microfiltration membrane with a pore size of 0.22-0.45 μm to remove activated carbon and insoluble impurities;

[0011] (4) Crystallization: The filtrate obtained in step (3) was cooled to 10-20°C at a rate of 0.5-1.5°C / min under stirring, and kept warm for crystallization for 2-4 hours;

[0012] (5) Separation and drying: The crystal slurry obtained in step (4) is centrifuged, the wet crystals are rinsed with ice deionized water, and vacuum dried at 50-60° C. to constant weight to obtain refined ammonium chloride crystals.

[0013] Furthermore, in the above-mentioned refining method, in step (1), the industrial-grade ammonium chloride raw material meets the following requirements: lead (Pb) ≤ 50 ppm, arsenic (As) ≤ 20 ppm, sulfate (as SO42-) ≤ 500 ppm; and the stirring speed during dissolution is 200-400 r / min.

[0014] Furthermore, in the above refining method, in step (2), the activated carbon is food-grade powdered activated carbon with a specific surface area of ​​≥1000m 2 / g; adsorption stirring speed is 300-500r / min.

[0015] Furthermore, in the above-mentioned refining method, in step (2), the food-grade powdered activated carbon is activated by phosphoric acid before use. The activation method is: immersing the activated carbon in a 30% phosphoric acid solution (solid-liquid ratio 1:5), treating it at 90°C for 2 hours, washing it with water until it is neutral, and drying it at 120°C.

[0016] Furthermore, in the above refining method, in step (3), the microfiltration membrane is a ceramic membrane or a polyvinylidene fluoride (PVDF) membrane; and the filtration operating pressure is 0.1-0.3 MPa.

[0017] Furthermore, in the above-mentioned purification method, during the crystallization process of step (4), ammonium chloride seeds are added to the filtrate, the seed addition amount is 0.01-0.05% of the solution mass, and the seed particle size is 100-150 μm; the addition time is when the temperature is lowered to 35-40°C.

[0018] Furthermore, in the above refining method, in step (4), the crystallization cooling rate is 1.0-1.2°C / min; and the final crystallization temperature is 12-15°C.

[0019] Furthermore, in the above purification method, in step (5), the centrifugal speed is 2000-3000 r / min; the elution water temperature is 2-8°C, and the elution water volume is 10-20% of the mass of the wet crystals.

[0020] The present invention also discloses a food-grade ammonium chloride product prepared by the above method.

[0021] Ammonium chloride (NH4Cl) content ≥ 99.5%;

[0022] Total amount of heavy metals (as Pb) ≤ 5ppm;

[0023] Lead (Pb) ≤ 1ppm;

[0024] Arsenic (As) ≤ 0.5ppm;

[0025] Sulfate (as SO42-) ≤ 30ppm;

[0026] Water insoluble matter ≤ 0.005%;

[0027] Loss on drying ≤0.3%.

[0028] The invention also discloses that the food-grade ammonium chloride product is used as a dough regulator for baked foods, with an addition amount of 0.1-0.3 wt% of the flour mass; or as a yeast nutrient for fermented beverages, with an addition amount of 0.05-0.15 wt% of the fermentation liquid mass.

[0029] Compared with the existing technology, the present invention has the following advantages and beneficial effects:

[0030] The present invention realizes the efficient and green refining of food-grade ammonium chloride through the synergistic effect of activated carbon adsorption, precision membrane filtration and seed-induced crystallization. In terms of impurity removal, the deep adsorption of activated carbon combined with the precise interception of microfiltration membrane significantly reduces the residual heavy metals and sulfates, and the product purity far exceeds the food-grade standard; in crystal quality control, the seed addition and gradient temperature control strategy effectively inhibit the inclusion of impurities, forming high-purity crystals with uniform particle size, which greatly improves the dissolution rate and fluidity. At the process level, membrane filtration technology replaces traditional filtration methods, avoiding secondary contamination while ensuring the microbial retention rate, and the entire process does not require organic solvents or ion exchange resins, which meets the requirements of green production. The final product shows better processing performance in food industry applications, can effectively ensure the dough extensibility, fermentation activity and flavor purity, and provides reliable raw material support for high-end food additives. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below. However, it should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the scope of the invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention. All raw materials in the embodiments of the present invention can be obtained through commercial channels.

[0032] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0033] Table 1: Raw materials

[0034]

[0035] Example 1

[0036] All examples and comparative examples use the same industrial grade ammonium chloride raw material:

[0037] Lead (Pb) = 40ppm, Arsenic (As) = 15ppm, Sulfate (SO4 2- )=400ppm.

[0038] A method for refining food-grade ammonium chloride, comprising:

[0039] (1) Dissolution: Take 5 kg of the above-mentioned industrial ammonium chloride raw material, add 15 L of deionized water, and stir at 80°C and 300 r / min to dissolve until saturated;

[0040] (2) Activated carbon adsorption: Add 50 g of food-grade powdered activated carbon (specific surface area 1050 m2 / g, activated with 30% phosphoric acid) and stir at 80°C and 400 rpm for 1.5 hours;

[0041] (3) Precision membrane filtration: Cool to 45°C and filter with a PVDF microfiltration membrane (pore size 0.3 μm, operating pressure 0.2 MPa);

[0042] (4) Crystallization: When the filtrate was cooled to 35°C at a rate of 1.0°C / min, ammonium chloride seed crystals (particle size 120 μm, addition amount 0.03%) were added, and the temperature was further cooled to 15°C and kept warm for 3 hours for crystallization;

[0043] (5) Separation and drying: centrifuge at 3000 r / min for 8 minutes, rinse the wet crystals with 4°C deionized water (water volume 15%), and dry them in a vacuum at 55°C.

[0044] Example 2

[0045] Method adjustment points:

[0046] (2) Activated carbon addition amount 1.5% (specific surface area 1150m 2 / g, unactivated);

[0047] (3) Ceramic membrane filtration (pore size 0.4 μm, pressure 0.15 MPa);

[0048] (4) Cooling rate 1.2°C / min, seed addition amount 0.05% (particle size 150 μm);

[0049] (5) The rinsing water temperature is 6°C and the water volume is 10%.

[0050] The remaining steps are the same as in Example 1.

[0051] Example 3

[0052] Method adjustment points:

[0053] (2) Activated carbon addition amount 0.5% (specific surface area 1300 m2 / g, activated by phosphoric acid);

[0054] (4) Without seed addition, crystallization was performed at a cooling rate of 0.8°C / min to 12°C;

[0055] The remaining steps are the same as in Example 1.

[0056] Comparative Example 1

[0057] Cancel activated carbon adsorption:

[0058] Directly skip step (2), and the rest is the same as in Example 1.

[0059] Comparative Example 2

[0060] Ordinary filtration instead of membrane filtration:

[0061] In step (3), filter paper (pore size 10 μm) was used for filtration, and the rest was the same as in Example 1.

[0062] Comparative Example 3

[0063] Cancel seed crystal and cool down at high speed:

[0064] Step (4) was performed without seed crystals and with a cooling rate of 2.0°C / min. The rest of the steps were the same as in Example 1.

[0065] Comparative Example 4

[0066] Excessive use of inferior raw materials:

[0067] In step (1), industrial ammonium chloride with Pb=65ppm and SO42-=600ppm is used, and the rest is the same as in Example 1.

[0068] Comparative Example 5

[0069] Membrane operating pressure exceeds the range:

[0070] The filtration pressure in step (3) is 0.05 MPa, and the rest is the same as in Example 1.

[0071] Application Examples

[0072] Take the refined ammonium chloride product obtained in the examples or comparative examples:

[0073] Baking application: Add 0.2% of flour mass to bread dough;

[0074] Fermentation application: Add 0.1% of the fermentation liquid mass to beer wort.

[0075] Test Example 1

[0076] Comparative test of refining efficiency and product purity

[0077] 1. Purpose

[0078] The purification effect of the refining process of the present invention on industrial-grade ammonium chloride was verified, with a focus on evaluating the heavy metal removal rate, sulfate retention capacity, and crystal physical properties.

[0079] 2. Test subjects

[0080] The refined ammonium chloride products obtained in Examples 1-3 and the comparative samples obtained in Comparative Examples 1-5.

[0081] 3. Test methods

[0082] 1) Key impurity detection

[0083] Heavy metals (Pb, As): determined by inductively coupled plasma mass spectrometry (ICP-MS, model: Agilent 7900);

[0084] Sulfate (SO4 2- ): Ion chromatography (ICS-600, Thermo Fisher);

[0085] Water-insoluble matter: Dissolve 10 g of sample in 100 mL of deionized water, filter through a 0.45 μm filter membrane, and dry at 105 °C and weigh.

[0086] 2) Crystal property analysis

[0087] Particle size distribution: laser particle size analyzer wet method detection;

[0088] Dissolution rate: 1 g of crystals was added to 50 mL of 25°C deionized water and the complete dissolution time was recorded (stirring speed 200 r / min).

[0089] 3) Process stability verification

[0090] Membrane fouling index: After membrane filtration in step (3), the membrane flux attenuation rate (J / J0) was measured.

[0091] The test results are shown in Tables 2 and 3.

[0092] Table 2: Comparison of key indicators of refined products

[0093]

[0094]

[0095] (*P<0.01 vs Example 1)

[0096] Table 3: Process stability data

[0097] Group <![CDATA[膜通量衰减率(J / J0)]]> Crystal D50 (μm) Example 1 0.92 210 Comparative Example 2 0.65 85

[0098] Result Analysis

[0099] 1. Impurity removal effect

[0100] The removal rate of Pb and As in Example 1 was over 98% (raw material Pb 40 ppm → 0.8 ppm), which was significantly better than that in Comparative Example 1 (residual Pb 12.5 ppm) without activated carbon and Comparative Example 2 (residual Pb 8.3 ppm) with insufficient membrane filtration.

[0101] Comparative Example 4 (inferior raw materials) still cannot meet the food grade standard (Pb>5ppm) after refining because the initial impurities exceeded the standard.

[0102] 2. Crystal quality advantage

[0103] The crystal size of Example 1 is uniform (D50 = 210 μm), and the dissolution rate is increased by 73% compared with that of Comparative Example 3 (no seed crystal + rapid crystallization);

[0104] In Comparative Example 3, the crystals contained impurities due to the large degree of supercooling, and the water-insoluble matter reached 0.008%.

[0105] 3. Process stability

[0106] The membrane flux attenuation rate of the precision membrane filtration (Example 1) is ≤8%, while the flux of the ordinary filtration (Comparative Example 2) decreases by 35% due to blockage by colloidal impurities.

[0107] Test Example 2

[0108] Effect of crystallization process on solubility and fluidity

[0109] 1. Purpose

[0110] Verify the optimization effect of seed addition and temperature control strategy on product application performance

[0111] 2. Methods

[0112] Comparison group:

[0113] Example 1 (containing seed crystals + temperature control 1.0°C / min)

[0114] Comparative Example 3 (no seed crystal + rapid cooling 2.0°C / min)

[0115] Conventional method (natural cooling crystallization, no temperature control)

[0116] 3. Test items:

[0117] Dissolution rate: 1.0 g of crystals were added to 50 mL of 25°C deionized water, stirred magnetically (200 rpm), and the complete dissolution time (seconds) was recorded.

[0118] Encapsulated impurities: Filter the above solution through a 0.45 μm filter membrane, dry at 105°C, weigh, and calculate the water-insoluble matter content (%);

[0119] Fluidity: Determination of angle of repose (fixed funnel method) - the bottom of the funnel is 5 cm above the horizontal plane, the crystals flow freely to form a cone, and the protractor is used to measure the angle between the inclined surface of the cone and the horizontal plane.

[0120] The results are shown in Table 4.

[0121] Table 4: Effect of crystallization process on solubility and fluidity

[0122] Group Dissolution time (s) Water insoluble matter (%) Angle of repose (°) Example 1 32 0.003 32 Comparative Example 3 120* 0.018* 48* Conventional method 75* 0.010* 41*

[0123] (*P<0.01 vs Example 1)

[0124] Data Analysis

[0125] 1. Dissolution rate:

[0126] In Example 1, uniform prismatic crystals were formed due to seed induction, and the dissolution rate was increased by 73% compared with that of Comparative Example 3 (needle-shaped agglomerates);

[0127] 2. Impurity packaging:

[0128] In Comparative Example 3, due to rapid cooling, the crystals were encapsulated with impurities, and the water-insoluble matter content increased by 6 times;

[0129] 3. Liquidity

[0130] The angle of repose of Example 1 (32°) is significantly lower than that of Comparative Example 3 (48°), which proves that cubic crystals have better fluidity and are conducive to accurate feeding of food production lines.

[0131] 4. Conclusion

[0132] Seed addition (0.03%) combined with temperature control (1.0°C / min) can:

[0133] ①Shorten the dissolution time to 32 seconds, improving processing efficiency;

[0134] ② Reduce the impurity inclusion rate to 0.003% to ensure purity;

[0135] ③ Improve fluidity (angle of repose ≤ 32°) to meet the needs of industrialized food production.

[0136] Test Example 3

[0137] Application performance verification (baking)

[0138] Purpose

[0139] Testing the Function of Refined Ammonium Chloride in Dough Conditioning

[0140] Method sample: Example 1 product vs. commercially available food-grade ammonium chloride (purity 99.3%) Dough preparation:

[0141] Basic formula: 100g flour, 50mL water, 1.5g yeast, 0.5g salt Experimental group: add 0.2% of Example 1 product

[0142] Control group: Add 0.2% commercial product

[0143] Test indicators:

[0144] Ductility: tensile resistance (g) was measured using a texture analyzer.

[0145] Fermentation volume: volume increase (mL) after 1 hour of fermentation.

[0146] Finished product specific volume: bread volume / weight (mL / g).

[0147] The results are shown in Table 5.

[0148] Table 5: Application performance verification (baking)

[0149] index Example 1 group Commercially available product group Tensile resistance (g) 285* 340 Fermentation volume (mL) 315* 280 Finished product specific volume (mL / g) 4.8* 4.2

[0150] (*P<0.05 vs commercially available group)

[0151] in conclusion

[0152] Due to low impurity residue (SO4 2- ≤25ppm), the product of Example 1 significantly improved dough extensibility (resistance reduced by 16%) and fermentation activity (volume increased by 12.5%), proving that the refining process effectively retains the activity of functional ions.

[0153] Test Example 4

[0154] Membrane filtration efficiency and hygiene indicators

[0155] 1. Purpose

[0156] Verify the microfiltration membrane's ability to retain microorganisms and colloidal impurities.

[0157] 2. Methods

[0158] Microbial load: The filtrate from step (3) was tested for total bacterial count according to GB 4789.2-2016.

[0159] Colloid removal: Dynamic light scattering (DLS, Malvern Zetasizer) was used to determine the number of particles with a diameter greater than 0.2 μm in the filtrate.

[0160] Comparative group: Example 1 (PVDF membrane) vs. Comparative Example 2 (filter paper filtration).

[0161] The results are shown in Table 6.

[0162] Table 6: Membrane filtration efficiency and hygiene indicators

[0163]

[0164] (*Not detected: counted as <10)

[0165] in conclusion:

[0166] The precision membrane filtration (0.3 μm) of the present invention enables:

[0167] ①Microbial retention rate> 99% (reaching GB 25570-2010 Food Additive Hygiene Standard);

[0168] ② The removal rate of colloidal impurities is 15 times higher than that of ordinary filtration, avoiding the nucleation of impurities during the crystallization process.

[0169] Test Example 5

[0170] Application test (fermented beverages)

[0171] 1. Purpose

[0172] Verify its fermentation-promoting performance as a yeast nutrient.

[0173] 2. Methods

[0174] Beer wort fermentation:

[0175] Basic wort: 12°P, inoculated with Angel Brewer's Yeast S-04.

[0176] Experimental group: 0.1% of the product of Example 1 was added.

[0177] Control group: 0.1% industrial grade ammonium chloride (purity 98.5%) was added.

[0178] Monitoring parameters:

[0179] CO2 weight loss (g / 24h): core indicator of fermentation activity.

[0180] Diacetyl peak (mg / L): a key byproduct affecting flavor.

[0181] Fermentation end point: apparent fermentation degree (%).

[0182] 3. The results are shown in Table 7.

[0183] Table 7: Application Example Test (Fermented Beverage)

[0184]

[0185]

[0186] (*P<0.01 vs industrial grade group)

[0187] in conclusion:

[0188] Because the heavy metal Pb content is less than 1 ppm, the product of Example 1 significantly improves yeast activity (CO2 production +23%), and the low-impurity environment reduces undesirable metabolites (diacetyl reduced by 57%), confirming the critical value of food-grade purity to the fermentation process.

[0189] The above test case data is summarized in Table 8 below.

[0190] Table 8: Test case summary

[0191]

[0192]

[0193] Conclusion: The present invention realizes the efficient and green preparation of food-grade ammonium chloride through the core technology of activated carbon adsorption-membrane filtration synergistic impurity removal and seed-induced crystallization. The product purity, solubility and application performance are significantly better than those of traditional processes.

[0194] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, based on the innovative concept of the present invention, changes and modifications to the embodiments described herein, or equivalent structural or equivalent process transformations made using the contents of the present invention specification, directly or indirectly applying the above technical solutions to other related technical fields are all included in the scope of protection of the patent of the present invention.

Claims

1. A method for refining food-grade ammonium chloride, characterized in that: The following steps are involved: (1) Dissolution: Add industrial-grade ammonium chloride raw material to deionized water, stir and dissolve at 70-90°C until saturated, to obtain a saturated ammonium chloride solution; (2) Activated carbon adsorption: Add activated carbon to the saturated solution obtained in step (1), the amount of activated carbon added is 0.5-2% of the mass of the ammonium chloride raw material, and stir and adsorb at 75-85°C for 1-2 hours; (3) Precision membrane filtration: Cool the solution after treatment in step (2) to 40-50°C and filter it using a microfiltration membrane with a pore size of 0.22-0.45 μm to remove activated carbon and insoluble impurities; (4) Crystallization: The filtrate obtained in step (3) was cooled to 10-20°C at a rate of 0.5-1.5°C / min under stirring, and kept warm for crystallization for 2-4 hours; (5) Separation and drying: The crystal slurry obtained in step (4) is centrifuged, the wet crystals are rinsed with ice deionized water, and vacuum dried at 50-60° C. to constant weight to obtain refined ammonium chloride crystals.

2. The method according to claim 1, wherein: In step (1), the industrial-grade ammonium chloride raw material meets the following requirements: lead (Pb) ≤ 50 ppm, arsenic (As) ≤ 20 ppm, sulfate (as SO42-) ≤ 500 ppm; and the stirring speed during dissolution is 200-400 r / min.

3. The method according to claim 1, wherein: In step (2), the activated carbon is food grade powdered activated carbon with a specific surface area of ​​≥1000m 2 / g; adsorption stirring speed is 300-500r / min.

4. The method according to claim 3, wherein: In step (2), the food-grade powdered activated carbon is activated by phosphoric acid before use. The activation method is as follows: immersing the activated carbon in a 30% phosphoric acid solution (solid-to-liquid ratio 1:5), treating at 90°C for 2 hours, washing with water until neutral, and drying at 120°C.

5. The method according to claim 1, wherein: In step (3), the microfiltration membrane is a ceramic membrane or a polyvinylidene fluoride (PVDF) membrane; and the filtration operation pressure is 0.1-0.3 MPa.

6. The method according to claim 1, wherein: During the crystallization process of step (4), ammonium chloride seed crystals are added to the filtrate, the amount of seed crystals added is 0.01-0.05% of the mass of the solution, and the seed crystal particle size is 100-150 μm; The time to add is when the temperature drops to 35-40℃.

7. The method according to claim 6, characterized in that: In step (4), the crystallization cooling rate is 1.0-1.2°C / min; The final crystallization temperature is 12-15°C.

8. The method according to claim 1, wherein: In step (5), the centrifugal speed is 2000-3000 r / min; the elution water temperature is 2-8° C., and the elution water volume is 10-20% of the mass of the wet crystals.

9. A food-grade ammonium chloride product prepared by the method according to any one of claims 1 to 8, characterized in that: Ammonium chloride (NH4Cl) content ≥ 99.5%; Total amount of heavy metals (as Pb) ≤ 5ppm; Lead (Pb) ≤ 1ppm; Arsenic (As) ≤ 0.5ppm; Sulfate (as SO42-) ≤ 30ppm; Water insoluble matter ≤ 0.005%; Loss on drying ≤0.3%.

10. A use of the food-grade ammonium chloride product according to claim 8, characterized in that: It can be used as a dough conditioner in baked foods at a dosage of 0.1-0.3 wt% based on the mass of flour; or as a yeast nutrient in fermented beverages at a dosage of 0.05-0.15 wt% based on the mass of the fermentation liquid.

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