| HS Code | 611973 |
| Product Name | Food Grade Caustic Soda Pearls (E524) |
| Chemical Formula | NaOH |
| Cas Number | 1310-73-2 |
| Appearance | White spherical pearls |
| Purity | ≥99.0% NaOH |
| Food Grade Standard | E524 / FCC |
| Solubility | Soluble in water, ethanol, and glycerol |
| Melting Point | 318°C (604°F) |
| Molecular Weight | 40.00 g/mol |
| Packaging | 25kg PP/PE bags or 50kg drums |
| Quality | High quality |
| Price | Low price |
As an accredited Food Grade Caustic Soda Pearls (E524) | Food Grade Caustic Soda Pearls with High Quality and Low Price factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 25kg sealed polyethylene-lined bags, food-grade caustic soda pearls, high purity E524, safe handling, quality assured, competitively priced. |
| Container Loading (20′ FCL) | 20' FCL loaded with food-grade caustic soda pearls in sealed bags on pallets, ensuring safe, dry, contamination-free transport. |
| Shipping | Our food-grade caustic soda pearls are securely packed in moisture-proof, food-safe bags and sealed drums to ensure safe transit. We offer reliable global shipping with proper hazardous material documentation and fast dispatch. Bulk orders receive economical freight rates, ensuring high-quality product delivered safely to your destination. |
| Storage | Store Food Grade Caustic Soda Pearls in a cool, dry, well-ventilated area inside sealed, corrosion-resistant containers. Keep away from moisture, water, acids, and incompatible metals like aluminum or zinc. Store off the ground on pallets, protected from humidity and direct sunlight, with clear labeling and secure access. |
| Shelf Life | Shelf Life: 24 months from manufacture when stored sealed, cool, and dry; avoid moisture exposure. |
In continuous short-mix neutralization lines processing crude soybean oil with free fatty acid (FFA) concentrations between 0.9% and 1.4%, food-grade sodium hydroxide pearls (E524) are dissolved with deionized water to a processing concentration of 14–20°Bé, corresponding to approximately 9.5–15% w/w NaOH, in a 316L stainless mix tank fitted with a peripheral jet eductor; the heat of dissolution raises the bulk solution temperature to 80–95°C. Food-grade pearls used for this route are assayed as total alkali not less than 98.0% as NaOH under EU 231/2012, with carbonate content below 0.5% to limit foaming during solution preparation. Dosing is calculated from ISO 660:2020 or AOCS Ca 5a-40 FFA measurement, with 0.142 kg NaOH required per kilogram of FFA expressed as oleic acid, and a deliberate excess of 0.03–0.05% of oil mass is maintained to ensure complete neutralization to residual FFA below 0.2%. The solution is metered through a PTFE-diaphragm dosing pump into the crude oil stream after degumming and preheating to 85–90°C within a high-shear mixer; the mixture then enters a disk stack separator at 7,000–7,500 rpm to remove soapstock. From the primary separator, the neutralized oil is washed once or twice with potable water at 90–95°C and vacuum dried at 10 kPa absolute before bleaching and deodorising. Industry compliance standards include FDA 21 CFR 184.1760 for sodium hydroxide as a GRAS food substance, EU 231/2012 for the E524 monograph, and CODEX STAN 19-1981 for edible oils where applicable. Terminal finished product types are neutralized and washed crude vegetable oils that can be further refined to RBD soybean oil, sunflower oil, palm olein and canola oil for bottled cooking oil, mayonnaise, frying fats and margarine manufacture. Operational boundary: excess NaOH above 0.08% oil mass during short-mix neutralization produces viscous soapstock and increases neutral oil loss in the disk stack separator, while insufficient excess leaves FFA residuals above 0.2% and raises the subsequent deodorisation load.
Roasted nibs are charged into a steam-jacketed alkalization reactor and sprayed with a food-grade sodium hydroxide solution prepared from E524 pearls; the addition ratio is 0.5–2.0% NaOH by weight of nib mass, with target final pH determined by the application and measured in a 10% aqueous suspension. Conventional Dutch cocoa powders are adjusted to pH 6.8–7.5, while black cocoa powders require pH 7.8–8.6. The reactor is operated at 90–110°C under 2–4 bar for 30–90 min, during which the alkalizing agent neutralizes cocoa acids, polymerizes polyphenols and darkens the bean matrix; after reaction, the liquor is pressed, and the resulting cake is dried below 5% moisture before milling to a median particle size below 75 μm. Industry compliance standards include Directive 2000/36/EC for cocoa and chocolate products, CODEX STAN 105-1981 for cocoa powders, FDA 21 CFR 184.1760 for GRAS sodium hydroxide, and EU 231/2012 for the E524 monograph. Terminal finished product types are Dutch-process cocoa powder, cocoa liquor, dark compound coatings, chocolate-flavored bakery fillings and instant beverage powders. Operational boundary: total alkali dose above 2.5% of nib mass produces burnt bitter off-notes and can generate insoluble sodium carbonate residues; if the cake enters milling with moisture above 5%, particle agglomeration and microbiological instability are observed on production-scale pin mills.
| Application route | Regulatory reference | Technical monitoring parameter |
|---|---|---|
| Edible oil neutralization | FDA 21 CFR 184.1760, EU 231/2012, CODEX STAN 19-1981 | Residual FFA by ISO 660:2020 or AOCS Ca 5a-40; separatory bowl speed 7,000–7,500 rpm |
| Dutch cocoa alkalization | Directive 2000/36/EC, CODEX STAN 105-1981, EU 231/2012 | Final cocoa pH 6.8–8.6; moisture before milling below 5% |
| Pretzel lye bath | FDA 21 CFR 184.1760, EU 231/2012 | NaOH concentration 3–4% w/w; immersion time 10–20 s |
| Tomato and peach peeling | 21 CFR 113, 21 CFR 155.190, EU 231/2012 | Lye concentration 1.5–4.0% NaOH; dwell time 30–75 s |
| Spanish-style olive debittering | CODEX STAN 66-1981, EU 231/2012 | Penetration depth two-thirds to three-quarters flesh; brine pH below 4.5 |
| Hominy hull removal | FDA 21 CFR 184.1760, 21 CFR 117 | Total alkalinity titration; rinse pH below 8.5 |
Continuous dip-tank operations processing wheat flour doughs require direct viscosity management of the caustic bath because NaOH concentration declines as dough absorbs water and surface starch leaches into the lye solution. The formulation addition ratio for standard wheat pretzel dough is 3–4% w/w NaOH, which yields a strongly alkaline bath with pH above 13.0; the bath temperature is maintained at 90–95°C and immersion time is 10–20 s. Dough pieces are conveyed on a stainless steel chain through the lye tank, followed by potable water rinse nozzles that reduce surface pH to below 10.0 before coarse salt is applied; baking is performed in a tunnel oven at 220–250°C for 8–12 min, during which residual alkali accelerates Maillard browning and yields a dark mahogany crust with gloss. Compliance is governed by FDA 21 CFR 184.1760 for GRAS sodium hydroxide, EU 231/2012 for the E524 monograph, and 21 CFR 117 cGMP. Terminal products are Bavarian pretzels, lye rolls, lye bagels and German-style pretzel snacks. Operational boundary: immersion beyond 30 s produces a thick gelatinized surface layer that remains slippery after baking and can raise residual crust pH above 10.0, contributing to a soapy aftertaste; below 3% NaOH, browning is uneven and the crust lacks the characteristic alkali gloss.
Canned tomato and peach lines use food-grade sodium hydroxide as a tissue-loosening agent, but the addition ratio and contact time are crop-specific. For Roma tomato peeling, the lye bath is held at 1.5–2.5% w/w NaOH and 88–94°C, with a dwell time of 30–60 s; for clingstone peaches, concentration is raised to 2.5–4.0% w/w at 92–96°C for 45–75 s, depending on cultivar firmness and maturity. The lye-treated fruit passes through a rotary drum with rubber disc scrubbers and water sprays to detach epidermis and residual alveoli, then enters a citric acid dip of 0.5–1.0% to neutralize surface pH and prevent browning. In potato peeling, a more aggressive addition ratio of 10–15% NaOH at 75–85°C with 6–12 min contact is standard. Compliance is governed by 21 CFR 113 for thermally processed low-acid canned foods, 21 CFR 155.190 for canned tomatoes, and EU 231/2012 for the E524 monograph. Terminal finished product types include whole peeled tomatoes, diced tomatoes, peach slices, fruit cocktail, tomato puree, and frozen French fries. Operational boundary: for peaches, contact beyond 75 s at 4.0% NaOH results in measurable mesocarp softening and higher drained-weight loss after retort; for tomatoes, exhausted lye below 1.0% NaOH leaves adherent peel fragments that increase thermal process verification reject rates.
Spanish-style green olive processing is defined less by bacterial fermentation than by the initial lye treatment that hydrolyzes oleuropein, the bitter secoiridoid glucoside in the olive flesh. Food-grade sodium hydroxide solution at 1.8–2.8% w/w is circulated through fermentation tanks at 18–25°C for 8–12 h, with lye penetration stopped when the solution has reached two-thirds to three-quarters of the flesh depth; this is determined by cutting fruit cross-sections and staining with phenolphthalein. After lye drainage, the olives are washed in potable water 2–3 times over 8–24 h to remove residual alkali and oleuropein hydrolysis products, then placed in 4–6% NaCl brine for spontaneous Lactobacillus plantarum fermentation. Compliance is set by CODEX STAN 66-1981 for table olives, EU Reg (EC) 1334/2008 for flavourings where subsequent seasoning is added, and EU 231/2012 for the E524 monograph. Terminal products are Spanish-style green olives in brine, stuffed olives, and lye-treated oxidized black olives after subsequent aeration and ferrous gluconate treatment. Operational boundary: lye penetration to the pit destroys texture and permits rapid growth of yeasts if brine pH remains above 4.5; at concentrations below 1.5% NaOH, complete debittering may exceed 36 h and increases the risk of pectolytic deterioration.
Alkaline hull removal from yellow dent corn uses food-grade sodium hydroxide solution at 1.0–2.0% w/w, heated to 95–100°C in a jacketed batch cooker, with a contact time of 18–25 min. The hot lye solution hydrolyzes the pericarp and stone cell cement, allowing mechanical washers and degerminators to remove the hull and germ without fracturing the endosperm. After hull removal, the corn is rinsed and neutralized with dilute citric acid or potable water to reduce surface pH below 8.5 before canning or freezing. Compliance is based on FDA 21 CFR 184.1760 for GRAS sodium hydroxide, 21 CFR 117 cGMP, and EU 231/2012 for the E524 monograph; terminal products are canned hominy, frozen hominy grits, and pre-canned hominy for further maize-based side dishes. Published data for this specific configuration in modern continuous lines is limited, and manufacturers validate lye concentration via titration of total alkalinity every 15 min to control batch-to-batch hull-removal uniformity. Operational boundary: at NaOH concentrations above 2.5%, the cooked endosperm swells unevenly and produces higher starch loss in rinse water; below 0.8% NaOH, pericarp removal is incomplete and increases mechanical damage to the germ.
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Food Grade Caustic Soda Pearls (E524) | Food Grade Caustic Soda Pearls with High Quality and Low Price is supplied as white, spherical, hygroscopic pearls under product model FGCS-E524-99. The constituent is sodium hydroxide, CAS 1310-73-2, EINECS 215-185-5, food additive code E524. The solid form is free-flowing and packaged for dry-bulk logistics. Conformity is maintained with Commission Regulation (EU) No 231/2012 Annex II for E524, with FDA 21 CFR 184.1763, and with the current Food Chemicals Codex sodium hydroxide monograph. The minimum total alkali assay is 99.0% as NaOH, above the EU E524 solid-form minimum of 98.0%. Membrane-cell brine purification controls residual mercury below 1 mg/kg and lead below 2 mg/kg. Chloride is limited to ≤0.05% and sodium carbonate to ≤0.3%. The product has a molar mass of 39.997 g/mol, anhydrous density of 2.13 g/cm³, melting point 318°C, and boiling point 1388°C. The dry pearl form removes the 50% water burden of liquid caustic soda and the heated tank farm associated with freeze protection; unit cost per active kilogram is therefore optimized for facilities that receive bulk dry shipments and operate ambient storage. The main engineering trade-off is the addition of a make-down step with exotherm control and dust containment.
Food grade E524 is not interchangeable with technical grade sodium hydroxide for direct food contact or food processing aid applications. The distinction rests on residual heavy metal levels, documentation, and process controls, not on total alkali assay alone. In FDA 21 CFR 184.1763, sodium hydroxide is included as a direct food substance affirmed as GRAS when used in accordance with good manufacturing practice. In EU regulation 231/2012, E524 is a permitted food additive; the solid form is subject to the same monograph limits as other forms. Unlike weak acid acidity regulators, sodium hydroxide provides strong-base pH adjustment without buffering capacity. pH is highly responsive to small addition errors and should be controlled by metering rather than batch dumping.
NaOH is strongly deliquescent. At 20°C, the equilibrium relative humidity above a saturated sodium hydroxide solution is below 10%; however, the practical caking threshold for pearl beds is observed around 60% RH because the surface film must become continuous before capillary adhesion and CO₂ absorption accelerate. Above 60% RH, production-scale storage in unheated warehouses has shown loss of free-flowing character within 8–12 hours for open bags. The alkaline surface film absorbs atmospheric CO₂ to form sodium carbonate, reducing assay and increasing particle adhesion. Therefore closed transfer is specified: screw feeders, rotary valves, or vacuum conveying lines are purged with dried air having a dew point below −20°C. Sodium carbonate is analytically controlled on each lot; the product specification is set at ≤0.3% Na₂CO₃ to provide margin below the EU E524 limit of 0.5%. Brine purification in the membrane-cell process controls chloride and heavy metals at the source rather than by downstream blending.
| Parameter | Limit or range | Basis |
|---|---|---|
| Appearance | White spherical pearls | Visual inspection |
| Total alkali as NaOH | 99.0% min | EU 231/2012 titrimetric; FCC monograph |
| Sodium carbonate, Na₂CO₃ | ≤0.3% | EU 231/2012 titrimetric |
| Sodium chloride, NaCl | ≤0.05% | EU 231/2012 photometric |
| Iron, Fe | ≤10 mg/kg | ICP-OES |
| Lead, Pb | ≤2 mg/kg | AAS/ICP-MS |
| Mercury, Hg | ≤1 mg/kg | Cold vapour AAS |
| Arsenic, As | ≤3 mg/kg | Hydride AAS |
| Particle size distribution | ≥95% between 0.5 mm and 2.0 mm | ISO 565 test sieves |
In food processing, the product is dissolved to a working concentration of 0.5%–2.0% NaOH in beverage and brewery clean-in-place circuits and circulated at 60–80°C through 316L stainless steel sprayballs and plate heat exchangers. Dissolution is carried out by adding pearls to water, not water to pearls, because the heat of solution at infinite dilution is approximately −44.5 kJ/mol and localized boiling can occur if water is added to a deep bed. For lye peeling of tomatoes, peaches, and root vegetables, the working solution is 1%–3% NaOH at 60–95°C for 30–120 seconds, depending on cultivar and peel thickness. Spent lye is neutralized with food-grade acid before discharge. Olive debittering uses 1.0%–2.5% NaOH during the initial cure, followed by rinse cycles. Pretzel and baked-snack alkali dipping uses 0.5%–1.5% NaOH at 80–90°C. In sugar refining, E524 is used for alkalinity adjustment and impurity precipitation; published data for this specific configuration is limited, so dosing is controlled by clarified juice pHS and calcium hardness rather than a fixed mass ratio.
When hard make-up water is used to prepare lye peeling baths, dissolved calcium reacts with carbonate ions to form calcite scale on heat exchanger surfaces. The solubility product of calcium carbonate at 25°C is 3.36 × 10−9 (mol/L)². A sodium carbonate specification of ≤0.3% in the pearl product lowers the initial carbonate load relative to industrial-grade caustic soda in which carbonate can exceed 0.5%. In peeling lines operating at 60–95°C, hard water with 200–400 mg/L calcium hardness as CaCO₃ can precipitate scale on plate heat exchangers within a single production week when carbonate is not controlled. The use of food grade E524 pearls with low carbonate and the addition of demineralized water are therefore specified for extended run times. The remaining carbonate is still sufficient to buffer some water hardness, but not so high as to accelerate deposition. Complete carbonate removal is not targeted; some carbonate provides buffering in reused lye baths, so the product is maintained at 0.1%–0.3% rather than zero.
Compared with caustic soda flakes, spherical pearls generate a lower dust fraction and exhibit a more uniform angle of repose, typically 30–35°, which improves discharge from conical silos and gravimetric feeders. Flake material can interlock and bridge; pearl product does not exhibit the same planar interlocking. Compared with 50% liquid caustic soda, dry pearls eliminate the freezing point issue at −12°C to +12°C depending on concentration, but require a make-down skid and dust containment. The higher active alkali content per shipped tonne reduces transport cost per kilogram of NaOH. Dosing differs by form: liquid systems use positive displacement pumps and conductivity-based concentration control, whereas pearl systems use loss-in-weight screw feeders or eductor hoppers. In production-scale bakeries and olive processing lines, the pearl form is preferred when batch demand is intermittent and unheated storage is required because no recirculation loop or tank heating is needed. However, the dissolution step requires a dedicated stainless 316L make-down tank with an agitator or venturi eductor; direct addition to a process vessel without mixing is not recommended because localized high pH zones can exceed 13 and damage heat-sensitive food components.
| Parameter | FGCS-E524-99 pearls | Technical grade flake | 50% liquid sodium hydroxide |
|---|---|---|---|
| Active alkali as NaOH | 99.0% min | 98.0% nominal | 50.0% nominal |
| Sodium chloride | ≤0.05% | typically ≤0.3% | depends on feedstock |
| Mercury | ≤1 mg/kg | not food-additive controlled | not food-additive controlled unless food grade |
| Freezing point | not applicable | not applicable | −12°C to +12°C depending on concentration |
| Dust generation | low spherical dust | high platelet dust | none |
| Dosing equipment | loss-in-weight screw feeder or eductor hopper | screw feeder with dust extraction | metering pump with heated storage tank |
| Water freight | none | none | 50% water |
| Carbon dioxide absorption | surface film under high RH | high due to high surface area | moderate in storage tanks |
Compared with technical-grade sodium hydroxide pearls, food grade E524 is distinguished by lot-to-lot heavy metal control and food additive documentation rather than by a large difference in NaOH assay. Technical-grade pearl may have a comparable 99% assay but may not be suitable for direct food contact.
Substitution of 50% liquid NaOH by dry pearls shifts the engineering constraint from freeze protection and pump viscosity to make-down exotherm and dust control. Liquid 50% systems require heated storage tanks and recirculation lines when ambient temperatures fall below 12°C; pearl systems eliminate that heat load but introduce a dissolution step. In a typical make-down skid, water at 20–25°C is metered into an eductor hopper; the resulting solution temperature rises according to the enthalpy of solution. For a 2% working solution, the adiabatic temperature rise from pearl dissolution is approximately 5–8°C, which is within the tolerance of CIP return lines. For a 5% stock solution, the adiabatic temperature rise is approximately 12–15°C, and the dissolution tank is designed for 1.5 times the heat release of the maximum batch concentration. Conductivity-based concentration monitoring is used downstream. The absence of water freight reduces delivery frequency by a factor of two on an equivalent NaOH basis, although the receiving facility must provide a dry storage area with sealed bag handling. The choice between forms is therefore not a simple purity comparison but a balance of plant utility requirements, storage climate, and make-down capacity.
Higher assay does not materially change the dissolution rate, which is controlled by particle surface area, agitation, and water temperature. However, higher assay reduces the mass of inert or carbonate diluent and therefore increases the heat released per kilogram of solid charged. The enthalpy of solution to infinite dilution is approximately −44.5 kJ/mol; the local temperature at the solid-liquid interface can approach 80–90°C when pearls are added too quickly to a poorly agitated tank. This local exotherm accelerates the dissolution of the pearl surface but can damage polymer tank liners and cause localized boiling when water is added to a static bed of pearls. Therefore the standard make-down protocol is: fill the tank with 60–70% of the required water at 15–25°C, start agitation, add pearls at a controlled rate through an eductor or screw feeder, then add the remaining water. The final solution is recirculated through a static mixer for 5–10 minutes before concentration verification by conductivity or density. This protocol is used in both food processing and CIP applications; the higher assay of 99.0% simply permits a smaller charge mass to reach the same final concentration.
Aluminum, zinc, galvanized steel, and tin are incompatible with sodium hydroxide solutions and with moist pearls. The reaction with aluminum produces hydrogen gas and should be excluded from any make-down vessel or dosing line. Recommended contact materials for dissolution tanks, pipes, and fittings are 316L stainless steel, polypropylene, PVDF, and HDPE. At concentrations above 1% and temperatures above 50°C, 304 stainless steel may suffer stress corrosion cracking in chloride-contaminated NaOH service; 316L is preferred. Personnel exposure is controlled by local dust extraction or P2/P3 respirator during open bag handling, chemical goggles, and impervious gloves. Bags should be re-sealed immediately after withdrawal; partially used bags exposed to relative humidity above 60% may form surface crusts. The product should not be combined with acid CIP steps in the same line without an intermediate rinse because the neutralization heat is approximately −57 kJ per mole of water formed.
To support high-volume consumption, packaging configurations include 25 kg multi-wall bags, 50 kg HDPE drums, and 500 kg bulk bags with inner PE liners. For high-volume processing sites, dedicated silo deliveries by pneumatic trailer are available if the receiving silo is fitted with a desiccant air dryer and pressure relief. Storage bays should be dry, away from acids, ammonium salts, and organic peroxides. Unopened shelf life is 24 months from production date when stored at 10–30°C and relative humidity below 60%. Each lot is released against certificate of analysis covering assay, carbonate, chloride, iron, lead, mercury, and arsenic.
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