E500(iii) – sodium sesquicarbonate

E500(iii) Denotes sodium sesquicarbonate, the double salt of sodium carbonate and sodium bicarbonate, typically represented as Na₂CO₃·NaHCO₃·2H₂O. It Is a mildly alkaline food additive used as a pH regulator, acidity controller, chemical leavening base, and anti-caking agent. In The presence of food acids or heat it releases CO₂ from its bicarbonate fraction while the carbonate fraction elevates alkalinity, influencing browning and spread.

Caloric value (dry product, 100 g)
Approximately 0 kcal per 100 g (Inorganic compound with no metabolizable energy; used at low, application-dependent levels).

Key constituents
Sodium Sesquicarbonate crystals (Na₂CO₃·NaHCO₃·2H₂O) with controlled waters of crystallization.
Solution Species: Na⁺, HCO₃⁻, and CO₃²⁻ in acid–base equilibrium providing a moderately alkaline buffer.
Food-Grade Traces: NaCl, Na₂SO₄, very low acid-insoluble matter, and heavy metals below limits.
Engineered Particle Size And low residual moisture for flowability and dosing.

Production process
Natural Route: Mining and purification of trona (Na₂CO₃·NaHCO₃·2H₂O), followed by washing, low-temperature drying to retain hydration, milling, and classification to food grade.
Synthetic Route (Solvay-linked): Production of NaHCO₃ from brine, CO₂, and NH₃; Controlled blending with Na₂CO₃ to obtain the double salt; Washing and gentle drying.
Food-Grade Finishing: Optional recrystallization, particle-size calibration, assays for purity and alkalinity, and barrier packaging under GMP/HACCP with defined CCPs.

Technological and sensory properties
Buffering Action Stabilizes pH in the mildly alkaline range, promoting Maillard browning and golden color in baking.
Leavening Behavior Arises from the bicarbonate portion releasing CO₂ with acids or upon heating, while the carbonate portion contributes to browning and spread in cookies.
Gas Release Can Be smoother or more gradual than pure NaHCO₃, depending on acid choice, moisture, and particle size.
Secondary Roles Include anti-caking in dry blends and “milder” alkaline baths relative to pure carbonate.

Food applications
Cookies, Wafers, And Crackers For pH control and color; Quick batters (pancakes, chemically leavened cakes); Alkaline surface treatments for bakery items; Effervescent dry mixes. Typical Use Levels Range From a few hundred ppm to fractions of a percent, paired with acids at suitable NV.

Nutrition and health
The Ingredient Contributes sodium but no energy. Excess Alkalinity May leave alkaline off-notes; Formulations Should balance acids and bases, and total Na⁺ load should be considered for sodium-sensitive consumers.

Quality and specification themes
Assay As The Double Salt within specification; Controlled moisture; Neutral odor.
Solution pH, Alkalinity, Very low insolubles, and consistent granulometry are required.
Compliance With Contaminant Limits, traceability, and manufacturing under GMP/HACCP are expected.

Storage and shelf life
Store Cool And Dry in sealed barrier packaging; Control ambient RH to prevent caking.
Avoid Moisture And acidic vapors to prevent premature reactions and surface composition shifts between bicarbonate and carbonate.
Apply FIFO Rotation For predictable performance.

Safety and handling
Treat As A Mildly Basic Powder; Avoid eye/skin contact and dust inhalation; Use PPE during weighing and blending.
Segregate From Strong Acids And incompatible materials; Dose on a “quantum satis” basis with attention to acid NV.

Troubleshooting
Alkaline Or Soapy Aftertaste Indicates insufficient acid or overdose → Rebalance NV and reduce dosage.
Excess Browning/Bitterness Suggests pH too high or over-bake → Lower alkalinity and optimize the thermal profile.
Caking In Dry Mixes Points To high RH → Upgrade packaging barrier, include secondary desiccants, and adjust cut.
Irregular Gas Release Often Reflects moisture pickup or non-uniform particle size → Improve storage and choose tighter granulometry.

Sustainability and supply chain
The Natural Trona Route Reduces reagent use but has mining impacts, whereas Solvay-linked routes are energy and brine intensive. Environmental Performance Improves with efficient energy use, recyclable packaging, waste minimization, and effluent control against BOD/COD targets.

Cosmetic (INCI) functions
Listed As INCI “Sodium Sesquicarbonate.” Typical Functions Include pH adjuster/buffering agent, water softener/cleansing aid, light deodorant by acid neutralization, and bulking agent in powders.

Conclusion
E500(iii) Combines The Functionalities of bicarbonate and carbonate in one ingredient, enabling controlled CO₂ release, targeted browning, and buffering. Reliable Performance Depends On correct acid pairing (NV), moisture and particle-size control, and stable processing conditions.

Mini-glossary
pH — Measure of acidity/alkalinity; a key lever for flavor, Maillard browning, and leavening behavior.
CO₂ — Carbon dioxide; gas released during acid–base reaction or heating.
NV — Neutralization value; stoichiometric measure used to balance acids and bases in leavening systems.
Na⁺ — Sodium ion; contributes to total dietary sodium.
RH — Relative humidity; higher RH promotes caking and activity loss.
PPE — Personal protective equipment; gloves, goggles, and masks used for safe powder handling.
INCI — International Nomenclature of Cosmetic Ingredients; standardized cosmetic ingredient naming and function mapping.
GMP — Good Manufacturing Practice; hygiene and process controls ensuring consistency, traceability, and quality.
HACCP — Hazard Analysis and Critical Control Points; preventive food-safety system with defined CCPs.
CCP — Critical control point; a step where control prevents, eliminates, or reduces a food-safety hazard to acceptable levels.
FIFO — First in, first out; inventory rotation principle to use older lots first.
BOD/COD — Biochemical/Chemical oxygen demand; indicators of organic load in effluents and potential environmental impact.