DISTARCH PHOSPHATE

Distarch phosphate (INS/E-number E1412, CAS 55963-33-2) is a chemically modified starch in which phosphate groups create covalent crosslinks between starch chains. 
This crosslinking increases mechanical and thermal stability, reduces susceptibility to shear and acid hydrolysis, and—depending on degree of modification—can increase the fraction of starch that resists small-intestinal digestion (i.e., RS4 resistant starch). 
Distarch phosphate is widely used as a food additive (thickener, stabilizer, binder), and in non-food applications (cosmetics, pharmaceuticals, industrial formulations).
CAS: 55963-33-2. 
Common names / synonyms: Distarch phosphate; distarch phosphate (E1412); starch, hydrogen phosphate; starch phosphate ester; phosphate cross-linked starch; bisstarch phosphate; phosphated distarch phosphate
Starch basics (brief primer)

To understand distarch phosphate, a short primer on native starch is necessary. 
Native starch is a mixture of two polysaccharides built from α-D-glucose units: amylose (mostly linear α-1,4 chains) and amylopectin (highly branched α-1,4 with α-1,6 branch points). 
Starch granules are semicrystalline entities whose gelatinization, retrogradation, and enzymatic digestibility depend on botanical source, amylose content, granule size, and crystalline type. 
Chemical modification of starch (crosslinking, esterification, etherification, oxidation, substitution) alters these properties for intended functional uses. 
Distarch phosphate is a crosslinked, phosphate-esterified starch. 

Chemical structure and reaction chemistry
What is a distarch phosphate?
Distarch phosphate is produced when phosphate groups form ester linkages with hydroxyl groups on glucose residues in two distinct starch chains — effectively producing covalent inter-chain crosslinks (di- or poly-ester phosphate bridges). 
The crosslinking stabilizes the granular/gel network and resists shear, acid, and enzymatic attack relative to native starch. 
Typical reagents are sodium trimetaphosphate (STMP) and sodium tripolyphosphate (STPP) used singly or together, or phosphorus oxychloride (POCl₃) in some processes. 
Reaction pathways and reagents
STMP / STPP: Under alkaline conditions, STMP reacts with starch hydroxyls to form mono- or di-phosphate esters and can lead to crosslinks (distarch phosphate) when bridging occurs. 
STMP/STPP processes are common in industry and have limits on residual phosphorus content regulated in some jurisdictions. 
POCl₃ (phosphorus oxychloride): Reacts with starch hydroxyls to produce phosphate esters; historically used in some manufacturing processes. 
Its use requires careful control and downstream purification to remove chloride and acid residues. 

Degree of substitution (DS) and crosslink density
Degree of substitution (DS): average number of substituted hydroxyls per glucose unit; for crosslinked products the DS is typically low (values far below 1) but crosslink density (fraction of inter-chain bridges) is the more relevant functional parameter.
Residual phosphorus: often expressed as % P (w/w); regulatory limits exist for some phosphate-modified starches (e.g., certain limits in US CFR for STMP/STPP treatments). 
Residual P and DS correlate with resistance to digestion and functional properties. 
Raw materials and manufacturing processes
Raw starch sources
Distarch phosphate is produced from food-grade native starches: corn (maize), potato, tapioca (cassava), wheat, rice, and others. 
Botanical source affects granular morphology and functional outcomes (e.g., potato starch yields larger granules and different gelatinization behavior than tapioca). 

Typical industrial process (overview)
Slurry formation: Native starch is dispersed in water to form a slurry. 
pH adjustment and salt addition: Alkaline conditions (NaOH) are usually applied to activate starch hydroxyls for reaction; salts like NaCl or Na₂SO₄ may be used to control reaction and granule swelling. 

Addition of phosphorylating reagent: STMP/STPP blend or POCl₃ is added under controlled temperature and pH to permit esterification and crosslink formation. 
Reaction time, temperature, pH, and reagent ratios determine crosslink density. 
Quenching and neutralization: Reaction is quenched (neutralized) and the modified starch is washed to remove salts, unreacted reagents, and low-molecular-weight byproducts. 
Drying and milling: The product is dried and milled to the desired particle size and packaged. 
Variants and co-modifications
Acetylated distarch phosphate (E1414): combined crosslinking and acetylation to impart additional properties (emulsification, oil stabilization). 
Hydroxypropyl distarch phosphate (E1442): hydroxypropyl groups provide cold-water solubility/clarity along with crosslink stability. 

Physicochemical properties
Properties depend on source starch and modification degree; typical reported properties:

Granular and molecular
Granule integrity is often maintained to some extent in low-to-moderate crosslinking regimes; high crosslinking reduces granule swelling. Particle size reflects native starch source. 

Thermal properties

Gelatinization temperature often increases with crosslinking (higher thermal stability). 
Crosslinking reduces peak viscosity in pasting profiles but improves stability under shear and high temperature. 
Differential scanning calorimetry (DSC) and Rapid Visco Analyzer (RVA) profiles are standard characterization tools. 

Rheology and functional performance
Improved freeze–thaw stability, reduced syneresis, improved resistance to acid and shear, and better paste clarity (depending on modification) are key functional advantages for sauces, fillings and frozen foods. 
Distarch phosphate contributes minimal viscosity at low inclusion levels in some formulations but provides network stability. 

Digestibility / resistant starch
Depending on crosslink density, distarch phosphate (and related phosphated crosslinked starches) can contain significant fractions of RS4 resistant starch (reported ranges in literature vary widely; some preparations report 70–85% RS4 in certain phosphated distarch phosphate products used for functional bread and reduced glycemic response). 
This property has implications for dietary fiber labeling and metabolic effects.

SAFETY INFORMATION ABOUT DISTARCH PHOSPHATE

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