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Sodium Acid Pyrophosphate (SAPP 28) is a white, crystalline powder used primarily as a leavening agent in the food industry.
Sodium Acid Pyrophosphate (SAPP 28) reacts with baking soda (sodium bicarbonate) to release carbon dioxide, which helps doughs and batters rise.
The "28" refers to the rate of reaction — SAPP 28 is a slower-reacting grade compared to other types like SAPP 40.
It is valued for providing controlled leavening in baked goods, especially in frozen and refrigerated dough products.
Beyond baking, it's also used in potato processing to prevent darkening and in seafood processing to retain moisture and improve texture.
CAS Number:
7758-16-9
Synonyms:
Disodium dihydrogen diphosphate,Disodium pyrophosphate,SAPP,Sodium acid diphosphate
Sodium pyrophosphate, acidic,Sodium dihydrogen diphosphate
Introduction
Definition and chemical classification
Background on phosphates and food additives
Historical discovery and development of SAPP
Industrial relevance of SAPP 28 in comparison to other phosphate salts
Chemical Identity
IUPAC name: Disodium dihydrogen diphosphate
Molecular formula: Na₂H₂P₂O₇
CAS Number: 7758-16-9
Molecular weight
Structural formula and 3D configuration
Synonyms and trade names
Difference between SAPP 28 and other SAPPs
Physical and Chemical Properties
Appearance (white crystalline powder)
Solubility in water
pH in solution
Melting and decomposition point
Hygroscopicity
Thermal stability
Reactivity with acids, bases, and other salts
Grades and Classification
Explanation of SAPP grades (SAPP 15, SAPP 28, SAPP 40)
Basis of classification (Rate of Reaction Index)
SAPP 28 characteristics (intermediate release rate)
Role of grades in application selection
Comparison table of SAPP grades
Synthesis and Manufacturing Process
Raw materials (phosphoric acid and sodium carbonate/sodium hydroxide)
Chemical reaction mechanisms
Process flow diagram of industrial production
Batch vs. continuous production
Purification and drying techniques
Quality control parameters and specifications
Environmental considerations during production
Applications
a. Food Industry
Role as a leavening acid in baked goods
Dough conditioning and texture improvement
Color stabilization in processed potatoes and meats
pH regulation in food systems
Detergent Industry
Water softening properties
Synergistic effects with surfactants
Soil suspension and anti-redeposition behavior
Water Treatment
Role as a dispersing agent
Metal sequestration and scale prevention
Ceramics and Industrial Uses
Binder in ceramic and refractory materials
Dispersant for clay and other slurry systems
Functionality in Baking and Leavening
Mechanism of carbon dioxide generation with sodium bicarbonate
Reaction kinetics of SAPP 28 (medium rate of CO₂ release)
Influence of temperature and moisture
Effects on dough expansion, crumb structure, and final product texture
Compatibility with other baking ingredients
Applications in frozen and refrigerated doughs
Health and Safety
Acceptable Daily Intake (ADI) established by regulatory bodies
Metabolism and excretion in humans
Acute and chronic toxicity data
Effects on calcium and phosphorus balance
Reproductive and developmental toxicity studies
Allergenicity and hypersensitivity
Occupational exposure considerations
Regulatory Status
Status as a Generally Recognized As Safe (GRAS) substance (FDA)
EU Food Additive number: E450 (i)
Permitted uses and maximum limits in various food categories
Global regulatory comparison (USA, EU, Canada, China, Codex Alimentarius)
Labeling requirements in packaged foods
Environmental Impact
Environmental fate and biodegradability
Contribution to phosphate pollution and eutrophication
Treatment of waste streams containing SAPP
Regulations governing industrial discharge
Mitigation strategies and best practices
Analytical Methods
Titrimetric methods for phosphate content
Gravimetric determination
Ion chromatography and HPLC
Spectrophotometric methods
ICP-MS for trace metal contaminants
Quality control parameters in food-grade and industrial-grade SAPP
Stability and Storage
Shelf-life of SAPP 28 under different conditions
Moisture sensitivity and packaging requirements
Compatibility with other food and chemical ingredients
Storage guidelines for industrial and retail settings
Advantages and Disadvantages
Advantages:
Reliable and controlled leavening behavior
Multipurpose functionality in diverse industries
Readily available and cost-effective
Disadvantages:
Potential contribution to phosphate overload in diets
Environmental concerns related to phosphorus
May interact unfavorably with some ingredients (e.g., aluminum-containing additives)
Future Trends and Research
Development of low-phosphate or phosphate-free leavening systems
Encapsulation technologies for improved stability and release control
Use in clean-label and organic formulations
Sustainability improvements in manufacturing
Biomedical and pharmaceutical research potentials
Alternatives and Substitutes
Other acidulants (e.g., monocalcium phosphate, sodium aluminum phosphate)
Natural alternatives (e.g., cream of tartar, citric acid, vinegar)
Performance comparisons
Feasibility in different product matrices
Conclusion
Summary of key findings
Reaffirmation of SAPP 28’s importance in modern industry
Prospects for sustainable innovation
Final thoughts on its safe and efficient use
SAFETY INFORMATION ABOUT SODIUM ACID PYROPHOSPHATE (SAPP 28)
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
