Junzheng Group Food Additive Caustic Soda

Junzheng Group food-grade caustic soda enters automated root and stone fruit processing lines as a recirculated immersion or spray bath in continuous lye peelers with screw or drum conveyance. The working bath is maintained between 3% w/w and 15% w/w NaOH, with lower levels around 3–5% w/w for thin-peel stone fruit and higher levels around 8–15% w/w for potato and tomato lines. Contact temperatures are controlled between 60 °C and 95 °C, and residence times range from 20 s to 3 min according to peel thickness, maturity, and pectin architecture. At bath strength below 3% w/w and 55 °C, commercial potato batches typically show incomplete peel removal and higher trim losses; at concentrations above 12% w/w and the upper temperature limit, surface starch gelatinizes and product yield declines. After lye contact, the disrupted peel is removed by steam injection and mechanical scrubbing in a rotary drum washer, followed by citric or malic acid neutralization and final inspection. Downstream operations include cutting, blanching, IQF freezing, or retort canning; terminal product types include canned diced tomatoes, peach halves, pear quarters, French fries, dehydrated potato flakes, and some frozen root vegetable cuts. Industry compliance is governed by FDA 21 CFR §184.1763 for GRAS status, EU Regulation (EC) No 1333/2008 for E 524 as a processing aid, GB 1886.20-2016 for food-grade sodium hydroxide specification, and Good Manufacturing Practice for residual removal. The lye solution is not a formulation ingredient in the finished food; it is a process aid whose carry-over is controlled by washing and acid neutralization. Solid caustic soda is diluted in stainless steel dosing systems with temperature control because heat of solution is exothermic, and the working bath concentration is verified by in-line density or conductivity measurement.

When NaOH Bath Temperature Diverges by 5 °C in Olive Lye Treatment

Table olive debittering depends on controlled alkaline hydrolysis of oleuropein and cell-wall pectin by food-grade caustic soda under narrow time-temperature control. Spanish-style green olive tanks are filled with lye solution prepared at 1.5–3.0% w/v NaOH and held at 15–25 °C for 8–14 h, with recirculation through stainless steel tanks, pumps, and heat exchangers. Lye penetration is checked by phenolphthalein; the lye front is usually stopped after reaching approximately two-thirds of the mesocarp thickness from the pit to the epidermis. A deviation of 5 °C above the set point can shorten the required penetration time by 20–35% in commercial Manzanilla or Hojiblanca lots, while accelerating pectin hydrolysis and increasing the risk of softened, sloughing outer tissue. At bath temperatures below 15 °C, lye penetration slows and the risk of fermentation instability increases; at temperatures above 25 °C, outer mesocarp softening can occur before the alkali front reaches the target depth. Commercial control therefore uses recirculation, cooling jackets, and in-line conductivity or density metering to hold caustic concentration against fruit absorption and atmospheric carbon dioxide neutralisation. Industry compliance includes CODEX STAN 66-1981, FDA 21 CFR §184.1763, and EU Regulation (EC) No 1333/2008 for E 524 as a processing aid. Terminal product types after washing, fermentation, or air oxidation include Spanish-style green olives in brine, California black ripe olives darkened by intermittent lye application and aeration, and debittered olive presentations packed in glass jars, cans, or flexible pouches. Lye is neutralized or diluted before final packing; final pH and salt concentration are adjusted separately from the lye step.

Neutralizing Free Fatty Acids Without Overdosing Caustic in Crude Oil Streams

In alkali refining, food-grade sodium hydroxide neutralizes free fatty acids in degummed crude oil prior to bleaching and deodorization. The stoichiometric sodium hydroxide requirement is 0.142 kg solid NaOH per tonne of oil per 1.0% FFA expressed as oleic acid; commercial corrections include an excess of 0.05–0.15 wt% of oil mass as solid NaOH equivalent, because residual phospholipids, moisture, and variable oil acidity consume caustic. Soybean, palm, rapeseed, sunflower, and corn oils are processed at 60–90 °C with centrifugal separation in disc-stack separators, using caustic solution at 8–14% w/w NaOH (12–20 °Bé). The neutralization reaction is rapid; the main operational bottleneck is subsequent soapstock separation. Overdosing produces excessive saponification of neutral triglycerides; based on triolein stoichiometry, 120 g NaOH can saponify approximately 885 g triolein, which increases refining loss and creates viscous soapstock that reduces centrifuge discharge. Underdosing leaves residual free fatty acids and insoluble soaps that load bleaching filters downstream. Process control uses AOCS Ca 5a-40 for free fatty acids, ISO 660:2020 for acid value, and in-line pH or conductivity sensors on separator feed. Soapstock viscosity under excess caustic is sensitive to phosphatide content and moisture; separators with automatic sludge discharge are usually set to discharge at intervals established by mass balance and back-pressure curves, but published data for specific separator configurations is limited.

After neutralization, the refined oil is water-washed, vacuum-dried, bleached, and deodorized; terminal product types include RBD soybean oil, RBD rapeseed/canola oil, RBD palm oil, RBD sunflower oil, and RBD corn oil for retail, food service, and further hydrogenated or interesterified products. Compliance at the refining step includes CODEX STAN 210-1999 for named vegetable oils, FDA 21 CFR §184.1763, EU Regulation (EC) No 1333/2008 for E 524 as a processing aid, and Commission Regulation (EU) No 231/2012 for purity. Sodium hydroxide is removed with soapstock; refined oil residual soap is monitored by AOCS Cc 17-95 after water washing. Actual caustic excess is verified by laboratory neutralization curves, and published data for some specific centrifugal configurations remains limited.

Alkalized Cocoa Nib Process Control and pH Limits

Cocoa nibs are treated with food-grade sodium hydroxide solution in jacketed stirred vessels before or after roasting to produce alkalized cocoa liquor and cocoa powder. The addition rate in nib alkalization is controlled by the buffering capacity of the nib; commercial use levels for sodium hydroxide are generally 0.5–1.5% of nib weight, prepared as a dilute solution and injected into the reactor to reach a target pH of 7.8–8.6 after mixing. Vessel temperatures are held between 80 °C and 110 °C for 30 min to 3 h, depending on atmospheric or pressurised alkalization, followed by drying, milling, and pressing. Over-alkalization above pH 8.6 can produce soapy, acrid flavor notes and excessive darkening with a decline in fat stability; under-alkalization below pH 7.5 yields poor water suspension and weak red-brown color development. The process is monitored by pH, moisture, and color measurements on the alkalized liquor. Compliance includes 21 CFR Part 163 for cacao products processed with alkali, EU Regulation (EC) No 1333/2008 for E 524 in cocoa and chocolate products, CODEX STAN 105-1981 for cocoa powders, and FDA 21 CFR §184.1763 for the sodium hydroxide source. Terminal product types include alkalized cocoa powders of varying color intensity, alkalized cocoa liquor for bakery coatings, and cocoa press cake for powder milling. Sodium hydroxide is selected when a controlled pH shift is required without introducing a large carbonate buffer load, particularly in nib processes where soluble color and neutralized acidity are critical.

What Happens to Dough Surface at 3–5% NaOH in a 30-Second Immersion?

Shaped dough pieces are immersed in a circulating caustic bath immediately before tunnel baking to modify surface starch and protein. The immersion bath is maintained at 3–5% w/w NaOH and heated to 85–95 °C; dough pieces are submerged for 8–20 s, allowed to drain, optionally topped with coarse salt, and then baked at 230–260 °C in tunnel ovens. At bath temperatures below 80 °C, surface starch gelatinization is incomplete and the finished crust remains pale; above 95 °C, steam evolution causes blistering and uneven sheen. Increasing bath strength above 5% w/w raises residual surface alkalinity and can contribute to soapy off-notes; below 2.5% w/w the characteristic chestnut-brown Maillard color does not fully develop during the short bake. The bath is not a dough ingredient; it functions as a surface starch modifier. Finished product types include soft pretzels, pretzel rolls, pretzel baguettes, and filled pretzel bites for frozen foodservice and retail bakery channels. Compliance in this application references FDA 21 CFR §184.1763, EU Regulation (EC) No 1333/2008 for E 524 as a processing aid, and plant-level hazard controls under occupational caustic-handling regulations. The final product is baked at sufficient time-temperature to neutralize surface alkali; residual alkalinity is evaluated by pH measurement of the homogenized crust.

Through controlled neutralization of lactic acid with food-grade caustic soda, liquid sodium lactate is generated for use as an antimicrobial or pH-control agent in food formulations. A 50% w/w sodium hydroxide solution is dosed into an 80% w/w lactic acid feedstock at 60–80 °C to pH 6.8–7.2; the stoichiometric ratio is 0.71 kg of 50% w/w NaOH solution per 1 kg of 80% w/w lactic acid. pH overshoot above 8.0 favors browning reactions with residual carbohydrate and may generate color bodies that carbon treatment must remove; pH below 6.5 leaves free acid and shifts equilibrium toward incomplete neutralization. The neutralized solution is decolorized with activated carbon, filtered, and evaporated to a commercial 60% w/w sodium lactate liquid. Equipment includes jacketed reaction vessels with pH-stat dosing control, activated carbon filtration, and thin-film or falling-film evaporators. Terminal product types include sodium lactate liquid for meat and poultry products under FSIS limits, humectant use in bakery fillings, and pH-buffering applications in beverages. Compliance includes the FCC Sodium Hydroxide monograph for caustic feedstock purity, 21 CFR 184.1768 for sodium lactate GRAS, EU Regulation (EC) No 1333/2008 for E 325, and 21 CFR §184.1763 for the sodium hydroxide source.