| HS Code | 926419 |
| Chemical Name | Sodium Hydroxide |
| Chemical Formula | NaOH |
| Cas Number | 1310-73-2 |
| Molecular Weight | 40.00 g/mol |
| Appearance | White flakes or pearls |
| Purity | ≥99.0% |
| Solubility | Easily soluble in water, releasing heat |
| Ph 1 Solution | ~13 |
| Melting Point | 318°C |
| Boiling Point | 1388°C |
| Density | 2.13 g/cm³ |
As an accredited Xinjiang Zhongtai Chemical Food Additive Caustic Soda factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Food additive caustic soda packed in 25 kg net double-layer PP woven bags with PE inner liner, moisture-proof and sealed. |
| Container Loading (20′ FCL) | 20′ FCL of Xinjiang Zhongtai Chemical food-grade caustic soda, securely packed in bags, containerized for safe transport. |
| Shipping | Xinjiang Zhongtai Chemical food-grade caustic soda ships in sealed, moisture-proof bags or drums, with ISO tanks for liquid form. Transport complies with IMDG/ADR regulations, requiring corrosion-resistant equipment, proper labeling, and separation from acids. Ensure dry, ventilated conditions and immediate spill response to maintain purity and safety. |
| Storage | Store in a cool, dry, well-ventilated area in tightly sealed, clearly labeled containers. Protect from moisture and humidity, as caustic soda is hygroscopic. Keep away from acids, metals like aluminum, and incompatible chemicals. Use corrosion-resistant secondary containment. Maintain Food Additive standards by preventing contamination. Ensure secure, upright storage with clear hazard signage. |
| Shelf Life | Shelf life typically 2 years when stored sealed, dry, and away from moisture and contaminants. |
In canned whole-peeled tomato and peach processing lines, Xinjiang Zhongtai Chemical food additive caustic soda is metered into 316L stainless steel dip tanks through conductivity-controlled dosing loops to maintain a sodium hydroxide concentration of 8–15 wt% for tomato cultivars and 10–15 wt% for peach halves, with bath temperature held at 85–95°C and residence time between 15–30 s for tomatoes and 30–60 s for peaches. For high-starch root materials entering frozen potato strip lines, the immersion liquor is diluted to 10–20 wt% NaOH and applied at 80–95°C for 120–300 s, with the longer residence window used for thick-skinned tubers processed in rotary drum peelers at 2–6 rpm. The hydroxide ion hydrolyzes pectic polysaccharides in the middle lamella of the fruit or tuber exocarp, loosening the skin so that low-pressure water sprays in the downstream rotary washer remove it without thermal damage to the flesh. Residual free alkali on peeled surfaces is neutralized with citric acid or malic acid to pH 4.0–4.5 before filling and retort or aseptic processing. The material used in this operation must conform to GB 1886.20-2016 or the FCC 13 sodium hydroxide monograph, and the application is permitted under FDA 21 CFR 184.1763 when used in accordance with GMP; within the EU, it falls under Regulation (EC) No 1333/2008 Annex II as E 524. Terminal product types include canned diced and whole peeled tomatoes, peach halves in syrup, frozen french fry cuts, and peeled potato slices for chip frying lines.
For Spanish-style green olive fermentation, lye treatment is conducted with 1.5–3.0 wt% NaOH solution at 15–25°C until the alkali front penetrates two-thirds of the flesh depth; immersion time typically falls between 8 h and 24 h. The solution is prepared in 316L mixing tanks and delivered to lye vessels through centrifugal pumps with flow control loops; temperature is maintained by plate heat exchange to limit the reaction exotherm. The hydroxide ion hydrolyzes oleuropein and related secoiridoid glycosides into non-bitter derivatives while low temperature and controlled concentration limit mesocarp softening. After lye drainage, olives are washed with potable water to remove free alkali and then brined at 6–8% NaCl in vertical cylindrical fermentation tanks where spontaneous or inoculated lactic acid fermentation reduces pH to 3.8–4.2 over 2–6 weeks. During this period, tank bottoms are sparged with nitrogen to limit oxidative browning and pellicle yeast growth. The process described must comply with Codex STAN 66-1981 for table olives, FDA 21 CFR 184.1763, and EU Regulation (EC) No 1333/2008 for E 524 use in table olive processing. Terminal product types include pitted green olives, pimento-stuffed olives, and dark ripe California-style olives processed by alternate lye and air oxidation steps.
Food-grade caustic soda is added to cocoa nibs as a dilute aqueous solution at 0.8–2.5 wt% of nib mass, commonly combined with potassium carbonate at total alkali doses of 1.0–3.5 wt% to achieve a finished cocoa powder pH between 6.8 and 8.2. The alkali penetrates the nib cotyledon cells, neutralizes volatile acidity, and weakens cell wall structure, shifting the powder color from light natural brown to dark mahogany and modifying dispersion behavior in dairy beverages. Alkalization is performed in indirectly steam-jacketed batch reactors or continuous tumblers at 70–110°C for 45–120 min; the moist mass is then dried to below 3% moisture and ground through air-classified cocoa mills. Terminal powder is standardized to 22–24% cocoa butter or 10–12% reduced-fat cocoa. The product must conform to Codex STAN 105-1981 for cocoa powders and EU Regulation (EC) No 1333/2008 where E 524 is listed for cocoa products; the sodium hydroxide input must meet the FCC 13 monograph or GB 1886.20-2016.
Within continuous centrifugal neutralization stations handling degummed crude soybean, palm, and rapeseed oils, food additive caustic soda is injected into high-shear in-line mixers immediately upstream of the primary disc stack centrifuge. The addition ratio is set at 0.142 kg NaOH per 1 kg free fatty acids expressed as oleic acid, plus an excess of 0.02–0.08% by bulk oil mass to drive residual acidity below 0.15% FFA. The lye stream is supplied at 14–18°Bé, equivalent to 9.4–12.7 wt% NaOH, and the oil-lye mixture is held at 80–95°C for 5–15 s in the mixing loop before separation. Neutralization produces sodium soaps that are discharged as soapstock from the heavy phase outlet; the oil phase is water-washed with 5–10 vol% soft water at 85–90°C in a second centrifuge to reduce residual soap to 10–30 ppm as sodium oleate. Acid value is monitored by ISO 660:2020 and free fatty acid titration by AOCS Ca 5a-40; the refined oil must conform to Codex STAN 210-1999 and the alkali source to GB 1886.20-2016 or FCC 13. Terminal product types include RBD soybean oil, RBD palm oil, and RBD rapeseed oil used as domestic cooking oil, margarine base stock, and industrial frying oil.
In industrial pretzel and lye roll bakeries, a food-grade caustic solution of 3–5 wt% NaOH is held at 85–95°C in electrically heated stainless steel dip tanks; proofed dough pieces are fully immersed for 10–30 s, drained, and salted with coarse sodium chloride before entering a continuous tunnel oven at 200–260°C for 12–18 min. The alkaline film raises surface pH to 11–12 and accelerates Maillard and caramelization reactions, producing a dark mahogany crust with a thin, glossy exterior. Immersion times below 10 s yield pale crust, while residence beyond 30 s can cause alkali burn and bitter off-flavor. Production lines typically recirculate the dip solution through a screen filter and titration controller to maintain NaOH concentration within ±0.2 wt% of setpoint; the bath is replenished with 50 wt% liquid caustic soda through a magnetic-drive metering pump. The operation is permitted under FDA 21 CFR 184.1763, and the lye must conform to GB 1886.20-2016 or the FCC 13 monograph; EU bakeries operate under Regulation (EC) No 1333/2008 for E 524. Terminal product types include Bavarian lye rolls, standard pretzel twists, pretzel sticks, and alkali-treated bagel surfaces.
When native corn or potato starch slurry is treated with sodium hydroxide to shift the reaction medium to pH 10.5–11.5 during etherification with propylene oxide or esterification with sodium tripolyphosphate, the alkali acts as a catalyst and swelling inhibitor rather than as a direct reactant. The addition ratio is 0.5–1.5 wt% NaOH on dry starch, metered into a 35–40% solids aqueous slurry held at 40–45°C in a jacketed reactor with top-entering agitation; the reaction time ranges from 8 h to 24 h. The hydroxide ion activates starch hydroxyl groups and prevents premature granule swelling that would otherwise increase viscosity beyond the mixer torque capacity. After the reaction endpoint is reached, the slurry is neutralized to pH 5.5–6.5 with dilute hydrochloric acid, washed through a continuous centrifuge, and flash-dried to 10–13% moisture. The finished modified starch must conform to FDA 21 CFR 172.892, the Codex GSFA provisions for modified starches, and EU Regulation (EC) No 1333/2008; the sodium hydroxide input must meet GB 1886.20-2016 or FCC 13. Terminal product types include retort soup thickeners, sauce stabilizers, low-viscosity bakery fillings, and cold-swelling dessert powders.
| Application zone | Compliance standard | Control parameter |
|---|---|---|
| Fruit and vegetable lye peeling | FDA 21 CFR 184.1763; GB 1886.20-2016; Regulation (EC) No 1333/2008 | 8–15 wt% NaOH; 85–95°C |
| Table olive debittering | Codex STAN 66-1981 | 1.5–3.0 wt% NaOH; 15–25°C |
| Cocoa alkalization | Codex STAN 105-1981; FCC 13 | pH 6.8–8.2; moisture <3% |
| Edible oil neutralization | ISO 660:2020; AOCS Ca 5a-40 | FFA <0.15%; soap 10–30 ppm |
| Pretzel and lye roll surface treatment | FDA 21 CFR 184.1763 | 3–5 wt% NaOH; 10–30 s immersion |
| Modified starch reaction pH adjustment | FDA 21 CFR 172.892; Codex GSFA | pH 10.5–11.5; 0.5–1.5 wt% NaOH on dry starch |
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Xinjiang Zhongtai Chemical Food Additive Caustic Soda is a membrane-cell electrolytic sodium hydroxide supplied as white solid beads, white flakes, and clear aqueous solutions. Solid forms are packaged in 25 kg double-layer HDPE bags; liquid grades are distributed at 30%, 32%, and 48% NaOH by mass in dedicated stainless steel or lined tank containers. The product family is differentiated by physical form and concentration rather than by chemical grade codes. The manufacturing route uses ion-exchange membrane electrolysis after primary brine purification, precipitation, filtration, and chelation. Because the cation-exchange membrane restricts chloride transport from the anolyte to the catholyte, the sodium hydroxide produced retains a low chloride burden. Traceability is maintained by batch number to membrane-cell unit, brine purification records, and final analytical certification.
The ion-exchange membrane process operates on purified brine with combined calcium and magnesium typically below 20 µg/L. Hardness at this level prevents membrane scaling and reduces insoluble impurities in the finished caustic. The electrolyser uses titanium anodes, nickel cathodes, and perfluorosulfonate/carboxylate bilayer membranes. Caustic concentration leaving the cells is normally in the range 30–33% NaOH. The liquor is cooled, filtered, and is either dispatched as liquid grade or concentrated in nickel or falling-film evaporators to 48% or to dry solid forms. In-process testing includes total alkali titration, turbidity, and trace metal analysis by inductively coupled plasma optical emission spectrometry. These unit operations exclude mercury and minimise diaphragm-related salt carryover.
The specification framework is based on GB 1886.20-2016 and the Food Chemicals Codex monograph for sodium hydroxide. Solid food additive grade is controlled to total alkali as NaOH not less than 99.0%. Sodium carbonate is limited to not more than 1.0%. Sodium chloride is maintained below 0.05%, a typical membrane-cell value, whereas diaphragm-cell grades may contain 0.8% or more if not further purified. Iron is limited to ≤0.001% to reduce trace pro-oxidant carryover in food and edible oil applications. Lead, arsenic, and mercury are controlled at ≤2 mg/kg, ≤3 mg/kg, and ≤0.1 mg/kg, respectively. Liquid grades are specified on an as-received basis; 30% liquid sodium hydroxide is supplied at 30.0–31.0% NaOH, and 48% liquid at 48.0–49.0% NaOH. Users should consult the batch certificate of analysis for specific values and the standard text for analytical method designations.
| Parameter | Solid food additive grade specification | Regulatory/standard basis |
|---|---|---|
| Total alkali as NaOH | ≥99.0% | GB 1886.20-2016 / FCC |
| Sodium carbonate as Na₂CO₃ | ≤1.0% | GB 1886.20-2016 / FCC |
| Sodium chloride as NaCl | ≤0.05% | GB 1886.20-2016 / FCC |
| Iron as Fe | ≤0.001% | GB 1886.20-2016 / FCC |
| Lead as Pb | ≤2 mg/kg | GB 1886.20-2016 / FCC |
| Arsenic as As | ≤3 mg/kg | GB 1886.20-2016 / FCC |
| Mercury as Hg | ≤0.1 mg/kg | FCC |
Solid bead and flake forms differ primarily in dissolution kinetics and handling. Bead grades with a nominal particle size of 0.8–1.2 mm exhibit lower dusting and more consistent free flow in pneumatic conveying systems than flake grades. In automated dissolving tanks, bead material is charged at controlled rates into water at 40–50°C, producing concentrated stock solutions that are subsequently diluted for use. This model distinction is operational rather than compositional; both bead and flake formats are released against the same chemical specification.
The primary technical distinction lies in the electrolysis cell and separator design. Diaphragm-cell caustic soda contains higher sodium chloride because the porous diaphragm permits brine migration into the catholyte. Industrial diaphragm-grade material commonly carries sodium chloride in the range 0.8–1.2% on a 100% NaOH basis, which can contribute to chloride-induced stress-corrosion cracking in 304L and 316L stainless steel at elevated cleaning temperatures. Mercury-cell caustic soda may have low chloride but introduces a mercury-exposure question in food and beverage plants; many food safety systems restrict mercury-cell material even when analytical mercury is below the specification limit. Membrane-cell product from Xinjiang Zhongtai Chemical avoids mercury entirely and yields sodium chloride typically below 0.05% on a 100% NaOH basis. The difference is confirmed in the certificate of analysis and directly influences corrosion behaviour in heat exchangers, spray balls, and storage tanks.
Compared with sodium carbonate, sodium hydroxide supplies a higher hydroxide-equivalent alkalinity per unit mass: 1 g of sodium hydroxide delivers 25 mmol of hydroxide, whereas 1 g of sodium carbonate delivers 18.9 mmol of carbonate alkalinity. Compared with potassium hydroxide, sodium hydroxide has a lower molar mass, 40.00 g/mol versus 56.11 g/mol for potassium hydroxide, so a smaller mass is required for equivalent hydroxide neutralisation. These stoichiometric distinctions matter when the final food formulation restricts sodium or potassium content or when alkalinity per unit mass is limited by dosing equipment.
The differentiation between food additive and technical-grade sodium hydroxide is not solely NaOH concentration. A technical grade may meet the same total alkali value but may not satisfy the heavy metal and chloride ceilings required by GB 1886.20-2016 or FCC. Electrolytic cell design, brine quality, evaporator metallurgy, and final packaging all affect trace contaminant levels. Membrane-cell food additive material therefore relies on selective separation and corrosion-resistant evaporator materials rather than on post-treatment additives.
During alkali refining of crude soybean, rapeseed, or palm oil, diluted sodium hydroxide is metered into the oil stream at 8–14% NaOH concentration and 70–90°C after degumming. The caustic neutralizes free fatty acids to sodium soaps, which are removed by disk-stack centrifugal separators. Free fatty acid reduction is monitored in accordance with ISO 660 or equivalent AOCS methods. The low iron content of food additive grade is operationally significant because trace iron can promote oxidative rancidity during subsequent bleaching, deodorization, and storage. Low chloride reduces pitting corrosion in plate heat exchangers, oil heaters, and centrifuge feed tanks handling heated crude oil with residual phosphatides and soapstock. Dosing is controlled by automatic metering pumps with feedback from pH or free fatty acid titration; batch strength is verified before unloading to avoid neutralization error.
Excess sodium hydroxide in edible oil neutralization is typically maintained at 0.05–0.15% of oil mass above the stoichiometric requirement for free fatty acids, depending on crude oil quality and phosphatide content. The soapstock phase is separated at 60–80°C; residual sodium soap in the oil is reduced by hot water washing or silica treatment. Food-additive-grade caustic with low iron preserves oxidative stability as measured by peroxide value under ISO 3960 and by anisidine value under ISO 6885.
In clean-in-place systems, sodium hydroxide is applied as a 2–5% solution at 70–85°C to remove proteinaceous and fat-based soils from dairy, brewery, and beverage lines. The caustic cycle is followed by potable water rinsing and acid wash. Food additive grade reduces the risk that heavy metals or chlorinated organics are transferred to product-contact surfaces after rinsing. In beverage pH correction and formulated water treatment, sodium hydroxide is added as a diluted solution to neutralize phosphoric or citric acids; the final heavy metal limits in the beverage are governed by national food safety standards, making food-grade caustic necessary at the input stream. In lye peeling of peaches, potatoes, or tomatoes, 1–3% sodium hydroxide is applied at 80–90°C for 15–60 s to loosen skins before mechanical peel removal and acid neutralization. The absence of mercury and low heavy metal content prevents contaminant retention on peeled surfaces.
After caustic circulation in CIP, the rinse is monitored by conductivity and pH; typical acceptance is final rinse water conductivity below 25 µS/cm or return to feed water pH. Residual caustic on a product-contact surface can cause local pH shifts that affect stability in cultured dairy products or beverages. Under caustic cleaning at 70–85°C, 304L stainless steel may be susceptible to stress-corrosion cracking when chloride concentration in the cleaning solution exceeds 50 mg/L and residual surface tensile stress is present. Low chloride in the caustic source is therefore a process control variable, not merely a regulatory parameter.
In drinking water pH adjustment and post-reverse osmosis remineralisation, sodium hydroxide is dosed at low concentrations, commonly 1–5 mg/L after reverse osmosis or distillation, to elevate pH and reduce corrosivity of demineralised water. Compliance with NSF/ANSI/CAN 60 or equivalent drinking water treatment chemical standards may be required by the owner or regulator. In water demineralisation systems, strong-base anion exchange resins are regenerated with 4–6% sodium hydroxide at 40–60°C; low chloride in the regenerant limits chloride loading on the anion bed and extends cycle capacity. For sugar refining, anion exchange decolorisation resins are also regenerated with dilute food-grade caustic; trace iron is relevant because iron can bind to resin sites and reduce colour removal efficiency. Published data for specific resin types and Chinese sugar refinery cycles is limited, but the operational preference for membrane-cell food additive grade is based on low chloride, low iron, and mercury-free cell chemistry.
The product is positioned for food and beverage supply chains requiring raw material documentation under GB 1886.20-2016, the Food Chemicals Codex, and relevant food safety system requirements. Certificates of analysis are issued per batch and may include total alkali, carbonate, chloride, iron, lead, arsenic, and mercury. Imported users may additionally require REACH registration or local food-contact chemical certifications; the manufacturer’s documentation should be requested for the specific jurisdiction. Published data for all possible regional certification configurations is limited, so the exact pack style, analytical method version, and regulatory delivery condition should be confirmed at the time of purchase.
Operational boundaries are governed by exothermic hydration and corrosion behaviour. Solid beads and flakes should be stored in sealed bags at relative humidity below 60% to prevent caking and carbonation. Liquid 48% sodium hydroxide must be stored above its crystallisation point, approximately 10–12°C, with heated or insulated storage in cold climates. Dilution is strongly exothermic; the addition order must be caustic to water with continuous agitation and heat removal. The product is incompatible with aluminium, zinc, tin, and their alloys, and with concentrated acids unless neutralization is engineered with cooling. It should not be mixed with halogenated solvents or amines without a documented compatibility review. For food applications, dilution water and dosing equipment should be constructed of 316L stainless steel or suitable polymer-lined carbon steel. Verification of concentration before use by titration against a recognised sodium hydroxide method is required when precise stoichiometric neutralisation is critical.
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