| HS Code | 181619 |
| Product Name | Caustic Soda 50% FG |
| Chemical Formula | NaOH |
| Cas Number | 1310-73-2 |
| Concentration | 50% w/w NaOH in water |
| Appearance | Clear, colorless liquid |
| Odor | Odorless |
| Specific Gravity | 1.53 at 20°C |
| Ph | 13.5 (1% aqueous solution at 25°C) |
| Boiling Point | Approximately 145°C |
| Freezing Point | Approximately 12°C |
| Solubility | Completely miscible with water |
| Grade | Food Grade, meets FCC requirements |
| Kosher Status | Kosher certified |
As an accredited Caustic Soda 50% FG, Liquid, NaOH Aqueous, Food Grade, Kosher and Meets FCC Requirements factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in 55-gallon drums, 275-gallon IBC totes, or bulk tankers; polyethylene-lined, sealed, labeled, and suitable for food-grade storage. |
| Container Loading (20′ FCL) | 20′ FCL loaded with flexitank or IBCs for food-grade caustic soda 50%, ensuring leak-proof containment, kosher integrity, and safe handling. |
| Shipping | Ship as UN 1824, Sodium Hydroxide Solution, Class 8 Corrosive, Packing Group II. Use corrosion-resistant drums, IBCs, or tank containers with proper hazardous cargo labeling. Segregate from acids and reactive metals. Ensure food-grade integrity, secure closures, and complete shipping documentation. Handle with spill containment and neutralization provisions. |
| Storage | Store in tightly sealed, chemically compatible containers (e.g., polyethylene or lined steel) in a cool, dry, well-ventilated area. Keep away from acids, aluminum, galvanized materials, and moisture. Maintain temperature above 12°C (54°F) to prevent freezing. Ensure containers are clearly labeled, protected from physical damage, and inaccessible to unauthorized personnel. |
| Shelf Life | Shelf life is 24 months from manufacture date when stored unopened in original containers, protected from freezing and contamination. |
Continuous corn nixtamalization for masa, tortilla, and tortilla chip production doses 50% food-grade sodium hydroxide directly from a day tank into the corn cook vessel. The dilution target in the cook water is 0.8–1.2% w/w NaOH relative to dry corn mass. Cook temperature is controlled at 88–95 °C for 30–60 min. In batch lines the corn is then steeped for 8–16 h at 50–70 °C. The resulting nejayote maintains a pH of 10.0–12.0 before discharge. Pericarp loosening is inadequate below 0.8%, producing masa with visible pericarp flecks. Above 1.2%, starch gelatinization at the kernel surface accelerates, yielding a sticky masa that blocks sheeting rollers. The 50% liquid grade is selected over solid flake because automated dosing in corn mills reduces dust formation and improves batch-to-batch alkali consistency. Post-steep washing in perforated drum washers removes excess alkali and dissolved pericarp. The masa moisture after stone grinding is held at 52–56%. For tortilla chips, the masa is sheeted to 0.9–1.2 mm, cut, baked, and fried. Distribution of residual sodium is monitored to maintain masa pH at 9.5–10.5, which influences texture and flavor. Compliance for this direct food use falls under 21 CFR 184.1763, and the solution must meet the FCC sodium hydroxide solution monograph. Kosher-certified material is required in masa lines supplying kosher tortilla and chip plants. Published data for specific residual sodium levels in commercial masa formulations is limited because masa pH and moisture are proprietary process targets. The primary process conflict is the narrow window between inadequate pericarp removal and over-gelatinization; experienced operators control the alkali-to-corn ratio and steep temperature within the ranges above.
High-volume peelers use a hot lye solution prepared by diluting 50% food-grade sodium hydroxide to 2–5% w/w NaOH for tomatoes and peaches, and up to 8–10% for potatoes. Immersion time in rotary drum peelers ranges from 30 s to 3 min at 60–95 °C. The lye hydrolyzes the pectic substances in the middle lamella beneath the skin. Peel slip is produced only when the solution penetrates the cuticle and reaches the cell wall region. If the NaOH concentration drops below the target because of organic acid carryover from the incoming product, peel removal becomes incomplete and finished cans show residual peel. If the temperature exceeds the upper limit, the flesh surface softens excessively and product yield falls. In continuous peelers, the 50% solution is metered into a recirculating lye bath with conductivity-based concentration control. The bath is replenished continuously because neutralization by fruit acids and peel debris reduces free alkalinity. Batch peeler operators commonly measure free alkali by titration and express it as % NaOH. The peeled product passes through a water spray wash and then through a rotary drum washer to remove loosened peel and reduce surface pH. Tomato and peach peelers often add a wetting agent approved for food use to improve lye contact. End products include canned whole tomatoes, diced tomatoes, peach halves, baby carrots, and frozen potato products. Compliance requires 21 CFR 184.1763 for the sodium hydroxide, FCC monograph purity, and kosher certification when the canned or frozen products are labeled kosher. Table 1 lists representative settings for three commodities.
| Commodity | NaOH concentration (% w/w) | Immersion time (s) | Temperature (°C) |
|---|---|---|---|
| Tomato | 2–4 | 30–90 | 85–95 |
| Peach | 3–5 | 45–120 | 80–92 |
| Potato | 8–10 | 60–180 | 85–95 |
Spanish-style green olive processing introduces the same 50% food-grade sodium hydroxide into the initial lye treatment without a separate header because the unit operation is identified by tank room records rather than by product grade. The lye solution is prepared at 1.5–3.0% w/w NaOH and is applied to the olives for 6–10 h at ambient temperature, typically 18–25 °C. The lye penetrates the olive flesh and hydrolyzes oleuropein, the bitter secoiridoid glycoside. Treatment is terminated when the lye front has reached approximately two-thirds of the distance from the skin to the pit. If the lye front stops short of this depth, bitterness remains after fermentation. If the front reaches the pit, the flesh softens excessively and the final fruit loses firmness. After lye treatment, the olives are washed in 2–3 changes of potable water over 12–24 h to remove residual alkali. The washed olives are then placed in 6–10% sodium chloride brine and undergo natural lactic acid fermentation. The fermentation pH is monitored until it reaches 4.0–4.5. Final products are green table olives, pitted cocktail olives, and sliced olive ingredients. The 50% solution must be food grade under FCC, kosher where required, and used within the limits of 21 CFR 184.1763. A process control issue in tank rooms is variation in lye uptake among olive lots with differing maturity; operators adjust lye concentration and contact time after cutting a sample fruit to check lye front depth.
Dutch processing of cocoa nibs or cocoa liquor uses alkali to raise pH and reduce acidity. Potassium carbonate is the most common alkali, but sodium hydroxide is used when the target cocoa powder pH must be shifted with a stronger base and when sodium content is not restricted by the finished formulation. The 50% food-grade sodium hydroxide is diluted before injection into the alkalization reactor. Typical dosage is 0.5–2.5% w/w based on cocoa nib mass, expressed as dry NaOH equivalent. The nibs are heated to 60–100 °C under controlled shear for 30–120 min. The alkali modifies tannin–protein interactions and reduces the perception of astringency. Final cocoa powder pH is measured on a 10% suspension in water, with typical Dutch cocoa powders ranging from 6.5 to 8.5. Alkali treatment also darkens the powder from reddish-brown to dark brown depending on pH and thermal load. The process is water-limited because excess moisture can cause lump formation in the reactor. The 50% solution is therefore metered with a mass flowmeter and mixed immediately into the recirculating nib mass. End products include Dutch-process cocoa powder, cocoa drinks, bakery coatings, and chocolate compounds. Compliance for food use is governed by 21 CFR 184.1763 in the United States and by Commission Regulation (EU) No 231/2012 for E 524 in Europe. FCC purity limits for heavy metals must be met. Kosher certification is required for kosher cocoa products. Published data for specific reaction rates in industrial cocoa alkalization with NaOH is limited, because process pH and color targets are proprietary. The main operational boundary is that sodium hydroxide reacts faster than carbonate and can overshoot pH if dosing is not tied to inline pH measurement after the reactor.
Hard pretzel and lye roll lines use a hot dip solution prepared from 50% food-grade sodium hydroxide. The dip concentration is typically 1–4% w/w NaOH and the bath temperature is maintained at 82–100 °C. The shaped dough pieces are immersed for 10–35 s, removed, and drained on wire mesh belts. The lye bath raises the surface pH above 11, which accelerates Maillard browning and produces the characteristic dark brown crust and glossy surface. If the bath concentration falls below 1%, browning is weak and the crust appears pale. If the concentration exceeds 4%, the surface can become slippery and the baked product may develop an alkaline aftertaste. Bath concentration is monitored by titration or inline conductivity and is replenished with 50% NaOH through a metering pump. Dough pieces carry starch and flour into the bath, which consumes free alkali and increases bath viscosity. Some continuous lines filter the recirculated lye through a screen filter to remove dough solids. The baked product surface pH is neutralized during baking and cooling but remains slightly alkaline in traditional pretzels. End products are hard pretzels, soft pretzels, lye rolls, and pretzel pieces. The 50% solution must meet FCC and 21 CFR 184.1763. Kosher-certified lye is required for kosher bakery operations. The process is sensitive to dough moisture: high moisture dough can dilute the lye bath and shift browning performance during long production runs. Published data for surface pH decay kinetics during pretzel baking is limited.
In edible oil neutralization, 50% food-grade sodium hydroxide is diluted with soft water to 10–20 °Bé or approximately 6–12% w/w NaOH. The diluted lye is metered into the crude oil stream after degumming and before the retention mixer. The free fatty acid content of the crude oil is measured by titration, expressed as % oleic acid. The stoichiometric NaOH requirement is calculated from the free fatty acid value, and a slight excess of 0.05–0.10% over stoichiometry is applied. Mixing in high-shear in-line mixers at 70–90 °C produces sodium soaps from the free fatty acids. The soapstock is then separated in high-speed disc stack centrifuges. The neutralized oil is washed with hot water to remove residual soap, and the wash water is separated by a second centrifuge. The target residual soap in the refined oil is below 50 mg/kg, as determined by AOCS Cc 17-95. If excess NaOH is too high, saponification of neutral oil increases yield loss. If excess NaOH is too low, residual free fatty acids remain and downstream deodorization cannot fully compensate for the residual acidity. End products include neutralized soybean oil, palm oil, sunflower oil, and canola oil prior to bleaching and deodorization. The use of food-grade NaOH is necessary because residual sodium may remain in refined oil and because the material is used in a food processing aid capacity. Compliance refers to 21 CFR 184.1763 and FCC purity. Kosher-certified caustic soda is required when the refinery processes kosher-certified oils. The high soap content in the centrifugal separator feed can cause emulsification at temperatures below 65 °C, so separators are often operated with hot process water at 90–95 °C.
CIP circuits in dairy, brewery, and ready-to-eat food plants prepare wash solutions from 50% food-grade sodium hydroxide at 1–3% w/w NaOH. The solution is circulated through stainless steel tanks, plate heat exchangers, and sanitary piping at 60–85 °C for 20–60 min. Spray balls and rotary jet heads deliver the alkali to the headspace and interior surfaces. The NaOH saponifies fats and hydrolyzes proteins, loosening organic soil. The wash is followed by an intermediate rinse and an acid wash, typically nitric or phosphoric acid, to remove mineral deposits. In dairy plants, the lye solution is monitored by conductivity and returned to the CIP tank. The solution is discarded when the conductivity falls below set point or when soil loading increases beyond the ability of the alkali to maintain pH above 12. Food-grade sodium hydroxide is specified because surfaces contact food after rinsing and because non-food grades may introduce heavy metals or odorous contaminants. Compliance is supported by FCC monograph, 21 CFR 184.1763, and plant sanitation requirements under 21 CFR 117. Kosher certification is not required for cleaning agents under most kosher programs because the agent is rinsed, but kosher certificates are often requested in kosher dairy facilities for audit documentation. End products are not direct, but the cleaned equipment is used to process milk, beer, sauces, and ready-to-eat meals. The main operational boundary is that spent lye may contain residual soil and must be neutralized before discharge to comply with local wastewater pH limits.
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Caustic Soda 50% FG, Liquid, NaOH Aqueous, Food Grade, Kosher and Meets FCC Requirements is an aqueous sodium hydroxide feedstock supplied at a nominal concentration of 50% w/w sodium hydroxide. The chemical identity is defined by CAS 1310-73-2, molecular formula NaOH, and molecular weight 39.997 g/mol. The product is a high-density, strongly alkaline liquid intended for food-manufacturing operations where sodium hydroxide is permitted as a process alkali under 21 CFR 184.1763 or 21 CFR 173.315, and where residue on food-contact surfaces or in finished food is controlled by validated processing. The grade designation “Caustic Soda 50% FG, Liquid, NaOH Aqueous, Food Grade, Kosher and Meets FCC Requirements” is not a catalogue part number; it describes the combination of 50% w/w concentration, food-grade compendial status, and liquid physical form. Suppliers assign internal material codes for bulk and packaged formats, and the certificate of analysis must state the supplier material code for traceability.
The product is normally produced by membrane-cell chlor-alkali electrolysis rather than older mercury-cell or diaphragm-cell routes because the membrane-cell catholyte provides a lower chloride, chlorate, and heavy-metal fingerprint suitable for food-grade applications. In membrane-cell operation, high-purity sodium chloride brine is polished by chelating ion exchange to a combined calcium and magnesium concentration typically below 20 µg/kg to protect the cation-exchange membrane. The catholyte produced at approximately 32 wt% NaOH is concentrated in nickel or high-nickel evaporators to 50% w/w, cooled, filtered, and transferred into dedicated stainless steel or approved non-metallic storage. This route matters because process-derived impurities such as sodium chloride, sodium chlorate, and iron influence the compendial toxic-element profile and the product’s suitability for food processing.
The difference between this product and technical-grade 50% sodium hydroxide is primarily analytical and operational rather than a difference in the active chemical species. Technical-grade material may be acceptable for neutralization but may carry higher levels of mercury, lead, iron, chloride, or chlorate from the cell technology and storage equipment. For food-grade material, the supplier controls the impurity profile against the FCC Sodium Hydroxide monograph, which includes toxic-element limits; the Kosher certification further constrains the use of shared equipment, certain defoamers, filtration aids, and tank cleaning agents. A technical-grade product cannot be converted to food-grade status by a simple certificate of analysis; the production, storage, and transport chain must be included in the certification scope.
For process design, the liquid has a density at 20 °C near 1.525 g/cm³, a crystallization onset near 12 °C in the NaOH–water system, and a dynamic viscosity at 20 °C near 78 mPa·s. These values shift with temperature and concentration; mass-flow measurement rather than volume measurement is therefore preferred for dosing. The composition is strongly alkaline, and the pH of the concentrated liquid is above 14, but pH alone is not a suitable release criterion for food-contact residue after rinsing.
The FCC designation is a compendial purity and identity standard, not a use authorization. The Food Chemicals Codex monograph for sodium hydroxide defines the assay and compendial impurity controls; compliance is confirmed by the lot-specific certificate of analysis. The Kosher designation is an additional process-certification layer: the certifying agency reviews production, storage, transport, and line-clearance procedures, but does not modify the chemical assay. The food-grade status is meaningful only when the end use is authorized. For direct addition as a food substance, 21 CFR 184.1763 permits sodium hydroxide under good manufacturing practice at levels not exceeding those required for the intended physical or chemical effect. For washing or lye peeling of fruits and vegetables, 21 CFR 173.315 may apply and requires residual removal appropriate to the process.
| Reference | Scope | Operational consequence |
|---|---|---|
| 21 CFR 184.1763 | Sodium hydroxide as a direct human food ingredient affirmed GRAS | Use quantity limited by GMP; final food must meet pH and residue specifications |
| 21 CFR 173.315 | Chemicals used in washing or to assist in peeling fruits and vegetables | Residual removal validated; peel waste handled under HACCP and wastewater controls |
| FCC Sodium Hydroxide monograph | Identity, assay, lead, mercury | Lot CoA must confirm compendial compliance before release |
| Kosher certificate | Process and logistics supervision | Approved carriers, tank trailers, and plant codes must match the certificate |
The Kosher designation is not a chemical property. A generic statement of kosher compliance without a lot-specific certificate is insufficient for food-manufacturer audits, because the certifying agency’s approval may be limited to a specific production site, packaging configuration, or logistics chain. Purchase specifications should include the certifying agency symbol, certificate issue date, and product code to prevent unauthorized substitution of technical-grade material.
Membrane-cell liquid sodium hydroxide at 50% w/w typically carries a lower chloride and chlorate burden than diaphragm-cell material, but the exact impurity profile is not fixed by the FCC designation alone. The table below is a representative certificate-of-analysis window for a commercial food-grade membrane-cell 50% liquid; it is not a regulatory limit and does not replace the supplier’s lot-specific certificate. Sodium chloride and sodium chlorate are the principal process-derived anionic impurities. Iron pickup is strongly influenced by storage metallurgy; carbon steel storage at elevated temperature can raise iron above the target even if the original product assay is acceptable.
| Parameter | Representative value | Reference or method |
|---|---|---|
| Sodium hydroxide assay as NaOH | 49.0–51.0 wt% | Alkalimetric titration; FCC Sodium Hydroxide monograph / ISO 979 |
| Density at 20 °C | 1.515–1.535 g/cm³ | ASTM D4052 / ISO 12185 digital density meter |
| Crystallization onset | ≈ 12 °C | NaOH–water phase equilibrium data |
| Dynamic viscosity at 20 °C | ≈ 78 mPa·s | Rotational viscometer; supplier rheology data |
| Sodium chloride as NaCl | ≤ 100 mg/kg | Ion chromatography; supplier CoA |
| Sodium chlorate as NaClO₃ | ≤ 20 mg/kg | Ion chromatography; supplier CoA |
| Iron as Fe | ≤ 5 mg/kg | ICP-OES; supplier CoA |
| Lead as Pb | ≤ 2 mg/kg | FCC Sodium Hydroxide monograph; ICP-MS |
| Mercury as Hg | ≤ 1 mg/kg | FCC Sodium Hydroxide monograph; cold-vapor AAS |
The sodium hydroxide assay is reported as total alkalinity as NaOH. Two-endpoint or titration methods referenced in the FCC monograph or ISO 979 are used. The 49.0–51.0 wt% window is not a sign of instability; it accommodates water balance drift in bulk storage, tank heel mixing, and minor evaporation. Sodium carbonate can increase over time if the tank is vented to ambient air, because carbon dioxide is absorbed at the liquid surface. Nitrogen blanketing or sealed venting with desiccation may be used to limit carbonate drift, but the food plant must verify that any blanketing medium and headspace equipment are compatible with caustic service and with Kosher requirements.
Compared with 25% liquid sodium hydroxide, the 50% material reduces water freight and storage volume but has a higher crystallization onset at approximately 12 °C. Outdoor tank farms in cold climates must be heat-traced and insulated; a bulk temperature set point of 15–20 °C is commonly used to avoid wall crystallization, but the actual minimum must be based on heat-transfer calculations at the coldest tank surface. Compared with 98% solid flake or anhydrous bead, the 50% liquid eliminates the dust and manual opening of bags, and avoids the need for an exothermic dissolution vessel. The heat of solution of sodium hydroxide to infinite dilution is approximately −44.5 kJ/mol, so solid dissolving or rapid dilution can raise local temperatures quickly; liquid dosing allows the heat release to be distributed across a controlled static mixer or dilution skid.
In cleaning-in-place systems, the 50% feed is diluted downstream of the metering point to working concentrations commonly in the 1.5–3.0 wt% NaOH range at 70–80 °C for stainless steel circuits, but the exact concentration and contact time are determined by the cleanability of the process soil and validated by cleaning verification. In vegetable lye peeling, the concentration, peel contact time, and temperature are product-specific; 21 CFR 173.315 governs the use but does not supply universal peel parameters. Published data for a universal lye-peeling concentration is limited because peel thickness, maturity, and surface wax influence the required alkali exposure. Process development must therefore be conducted on the specific fruit or root variety, and downstream waste neutralization must be addressed in the HACCP plan.
Dosing from 50% liquid into a dilution stream should be performed with mass-flow Coriolis metering or a calibrated positive-displacement pump. The density and viscosity require that pump discharge pressure and net positive suction head be calculated at the minimum storage temperature, not at nominal 20 °C. The use of a static mixer downstream of the injection point reduces localized high-pH regions and prevents precipitation of hardness ions when dilution water contains calcium or magnesium.
Storage below 12 °C can produce sodium hydroxide hydrate crystals; the remaining mother liquor changes concentration, and density stratification may lead to a misleading average concentration reading. A cold tank wall can build a crystal layer even when the centerline temperature probe reads above 12 °C. Heat tracing must be designed for the wetted geometry, with low-watt-density tracing and over-temperature protection. Mild recirculation is preferred over air sparging, because air sparging introduces carbon dioxide and accelerates sodium carbonate formation. If recirculation is used, the return line should be submerged to limit atmospheric contact.
Wetted-material selection for bulk storage and transfer includes 316L stainless steel for ambient and moderate temperatures. Above approximately 90 °C, nickel 200/201 or a high-nickel alloy may be required, particularly where chlorate, tensile stress, and temperature create stress-corrosion cracking risk. Aluminum, zinc, tin, brass, and glass should not be used in contact with liquid caustic. Gaskets, diaphragms, and seals are commonly EPDM or PTFE. Diaphragm metering pumps should have pressure-relief protection and no aluminum body parts. Dilution must be performed by adding caustic to water under agitation, never by adding water to a static concentrated caustic vessel. The addition rate must be limited by the maximum allowable temperature of the receiving tank and by the risk of local boiling at the dilution interface.
A food-grade FCC and Kosher designation does not remove the user’s obligation to validate residual removal on food-contact surfaces. For direct addition under 21 CFR 184.1763, the amount used must not exceed that required for the intended physical or chemical effect, and process records must demonstrate that the finished food or food-contact surface meets the site’s approved pH and residue criteria. For peeling uses under 21 CFR 173.315, residual neutralization and peel waste management remain process-control requirements.
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