Sodium tripolyphosphate (ST P P, food additive E451i)- salt of tripolyphosphoric acid

Physiochemical properties.

Appearance: loose powder white color. It can be produced in the form of granules. Easily soluble in water. We will not dissolve in ethanol. pH 9.1-10.1 (1% aqueous solution). When stored in a dry place, the shelf life of sodium tripolyphosphate is not limited.

Sodium tripolyphosphate has two varieties:

1) Formula Na 5 O 10 P 3 (E451i, STPP, Sodium triphosphate 5-substituted anhydrous, sodium tripolyphosphate anhydrous). Loss on drying no more than 0.7% (105 °C, 1 hour). Solubility in water 15 g/100 g water (at 20°C).

2) Formula Na 5 O 10 P 3 × 6H 2 O (E451i, STPP, Sodium triphosphate 5-substituted hexahydrate, sodium tripolyphosphate hexahydrate). Loss on drying no more than 23.5% (60°C for 1 hour holding, then 105°C for 4 hours holding).

Application.

Sodium tripolyphosphate is produced for food and technical purposes.

Technical sodium tripolyphosphate is used:

For liquefaction of thick pastes, clays, kaolins;

To regulate the pH of the medium;

For the manufacture of synthetic detergents, cleaning, bleaching, disinfecting, decontaminating agents (washing detergents, sinks, toilet bowls, cleaning bathtubs and washing glasses);

In the production of paper, leather, artificial materials (bleaching due to the stabilization of hydrogen peroxide);

In the production of medicinal and cosmetic preparations;

For corrosion protection, water treatment and other purposes (washing of boilers, softening of boiler feed water, prevention of precipitation and scale).

Food sodium tripolyphosphate is used:

To improve the texture of meat and fish products (increases pH and retains water in proteins, has the ability to break down myosin and actin);

As a melting salt in the production of processed cheeses,

As an additive in the production of cream, powdered and condensed milk, in the confectionery industry.

Sodium triphosphate according to GOST 13493-86 “Sodium tripolyphosphate. Specifications» is included in the list of raw materials in GOST 18236-85 Boiled pork products. Specifications”, GOST 18255-85 “Smoked and boiled pork products. Specifications”, GOST 23670-79 “Cooked sausages, frankfurters and sausages, meat loaves. Specifications".

Meat processing, as a rule, is done by dipping in an aqueous solution of sodium tripolyphosphate with exposure to the solution for 10-30 minutes. The temperature of the solution during processing is 18-36°C. A higher temperature corresponds to a shorter holding time. It is advisable to process fatty bacon by injection. In this case, the solution is injected directly into the meat layer.

Sodium tripolyphosphate is used to process pork in the form of minced meat, cut pieces or semi-finished products. For the case of joint treatment with sodium polyphosphate with common salt in a ratio of 0.125:0.75% and subsequent storage at a temperature of -23 ° C for 4 weeks, an improvement in the quality indicators of pork can be observed: color, aroma, taste, texture, and a decrease in water loss during heat treatment, the level of juiciness.

Sodium tripolyphosphate is used in the production of smoked legs in order to reduce moisture loss, and, accordingly, increase the yield of the finished product. In this case, the meat is treated with sodium tripolyphosphate together with table salt in a ratio of 0.3:3.0%. Processing increases the yield of the finished product by 5%.

For the treatment of beef and ground beef, treatment with a mixture of sodium tripolyphosphate and sodium pyrophosphate E450iii in a ratio of 25:75% is most effective. Processing improves the quality of the finished product: reduces water loss, improves color, texture, improves yield.

Sodium tripolyphosphate is used in the production of smoked pork loin. Pork is injected with a solution of sodium tripolyphosphate with a concentration of 0.3-0.5%. The level of injection is 5-10%. This treatment does not increase the juiciness of the finished product, but increases its tenderness.

Lamb carcasses are treated with a mixture of sodium tripolyphosphate and table salt in a ratio of 0.5:2.0%. This improves the tenderness of lamb carcasses, reduces losses during heat treatment. Processing increases the pH and any significant development unfavorable microorganisms are absent during storage for 6 days at a temperature of 0 to +4°C.

In order to increase the shelf life of chilled seafood fillets by 30-40%, treatment with an aqueous solution of a mixture of preservatives is used. The mixture has the composition: sodium tripolyphosphate 77%; potassium sorbate 12.7%; citric acid 10.3%. Processing is carried out by keeping the fillet in an aqueous solution. In this treatment, sodium tripolyphosphate inhibits the growth of microorganisms and stabilizes the state of the protein. Citric acid inhibits the development of microbiota by acidifying the fillet surface. Potassium sorbate inhibits the development of yeasts and molds.

Sodium tripolyphosphate is used to prevent corrosion of pipelines and heat exchangers. When using it, careful cleaning of heat exchangers and pipelines from deposits and fouling should be provided. When using sodium tripolyphosphate to create a protective phosphate film, the concentration of inhibitors in the water of the circulating system for 2-3 days should be taken as 100 mg / l (calculated as P 2 O 5), in additional water to maintain the phosphate film - 7-15 mg / l according to P 2 O 5 . In this case, the speed of water movement in heat exchangers must be at least 0.3 m/s.

Sanitary rules for enterprises food trade it is allowed to use detergents and disinfectants, which include sodium tripolyphosphate. After washing with such detergents, it is necessary to completely remove the cleaning solution from the treated surface.

The composition of synthetic washing powders depends on the hardness of the water. Three types of powders are produced: A, B, C.

Type A - for areas with water hardness above 5.35 meq.

Type B - for areas with water hardness below 5.35 mEq.

Type B - for areas with soft water, hardness not higher than 2 meq.

Type A and B powders prevent the formation of deposits in hard water.

Sodium tripolyphosphate is a component of DEZMOL, a synthetic detergent and disinfectant used to clean and disinfect equipment. The use of DEZMOL allows you to combine washing and disinfection of equipment in one operation. For manual washing, 0.5% aqueous solutions are used, and for mechanical processing, 1.0% aqueous solutions.

Sodium tripolyphosphate can be used as an independent detergent for washing linen and all types of fabrics, washing glasses, heavily soiled and greasy dishes, cleaning bathtubs, sinks and toilet bowls. Before washing, the laundry is pre-soaked in a warm solution of sodium tripolyphosphate (½ cup per bucket of water). Very soiled linen is recommended to be left in the indicated solution for 2-3 hours. Then the linen is washed and rinsed thoroughly in clean water.

Receipt.

Powdered sodium tripolyphosphate is a product of thermal phosphoric acid processing. Sodium tripolyphosphate is obtained by thermal dehydration of a mixture of orthophosphoric acids and its further vacuum crystallization.

Magazine "Heat Supply News", No. 11, (27), November, 2002, pp. 29 – 30, www.ntsn.ru

A.N. Fedenko, CEO, Rosplast LLC

Water treatment in industrial closed systems of energy and water and heat supply is a complex and rather expensive task. In the coolant of these systems, the concentration of impurities (anions, cations, suspended particles) occurs, exceeding the limits of their solubility. As a result, they form hard scale, interfere with heat transfer and reduce the performance of boilers by 10-20% or more.

Incorrect chemical water treatment or its absence can lead to an emergency situation at the enterprise.

PFN properties

Polyphosphate (PFN) has a large crystalline appearance, it is highly soluble in water, with stirring and for ease of use, it is currently produced in crushed form.

PFP is characterized by good solubility and the ability to form water-soluble complexes (chelates) with salts of Ca, Mg, Fe, Pb, Cd, Ni, Hg.

On fig. Table 1 shows data characterizing the amount of binding of Ca, Mg, Fe ions by some of the most common phosphates used in power plants for chemical water treatment. The calculation is based on the formation of complexes at room temperature.

Rice. 1. Chelating ability of phosphates.

A unique property of an inorganic polymer is its ability to maintain the polymer structure, both in the solid state and in aqueous solutions and melts.

Sodium polyphosphate is the most active water softener, because. forms stable complexes in a shorter time and at lower temperatures (20-40 o C) than sodium tripolyphosphate (STPP) and other phosphates.

The advantage of sodium polyphosphate over trisodium phosphate (TSP) is a higher content of phosphate in terms of P 2 O 5 - more than 63%. Compared to PFP, the content of phosphates in TNF in terms of P 2 O 5 does not exceed 25%. Recommendations and regulations indicate that the rate of application of PPP is 3-4 times less than that of TNF.

The advantages of PFN also include lower caking during storage, anti-corrosion properties, the ability to reduce iron oxide and copper scale formation on the internal heating surfaces of boilers.

Chelating ability (the ability to form water-soluble complexes, the stability of which is more than 1 year) makes it possible to apply SPF only once during the entire heating season. For comparison: the stability of sodium tripolyphosphate complexes is from 2 to 6 months, and trisodium phosphate is even less.

The disadvantages include the reduced pH value of aqueous solutions (pH ~ 7.5), as well as a more complex analysis of the concentration of aqueous solutions, a decrease in the alkalinity of boiler water. The pH value of the PFN solution is 7.5-8.0 versus pH 11-12 for TNF. To raise the pH value in the working solution of SPF, trisodium phosphate can be added in a small amount (about 50 g per 1 m 3 of the solution). Our company can produce ready-made mixtures based on PPP with specified indicators of the required pH values ​​and depending on the degree of hardness of the water consumed.

It should be noted that there is no corrosive activity of the PFN solution. The calculations of the NIIGIPROKHIM Institute, St. Petersburg, confirm the anticorrosive properties of PPP and give recommendations for its inclusion in the formulations of industrial inhibitors.

Ongoing studies of corrosion inhibitors with SPF show a decrease in the rate of corrosion in the water circulation systems of the enterprise from 0.6 mm to 0.1 mm per year. To prevent corrosion carbon steels in water, a concentration of PFI less than 10 mg / l is sufficient, depending on the hardness of the water.

Application practice

Consumer enterprises provide the following technology for the use of PFS. During the production tests of the PFP at the Zakamskaya CHPP-5 of Permenergo JSC, 3 boilers with a total steam capacity of 400-500 t/h were constantly in operation (purge - 8-12%).

The preparation of the solution is carried out in mixing tanks. Tanks are equipped with drainage, supply of coagulated water and steam 1.2 atm. To store the finished solution, there are measuring tanks.

The supply of phosphate solution to the boilers is carried out according to an individual-group scheme. From the measuring tanks, the working solution is fed to the inlet of the dosing pumps operating on a common manifold. Feed water is supplied to the collector through a check valve. Through control valves and limiting washers dy 3 mm, the diluted phosphate solution is distributed to the operating boilers.

The concentration of the working solution of trisodium phosphate before testing was 0.5-0.6% by RO 4 -3.

In comparative tests in the mixer V = 6.2 m 3 loaded 30 kg of PFP instead of 114 kg of TNF.

The polyphosphate dissolved fairly quickly with slight heating. The concentration of the resulting solutions was 0.62-0.65% by RO 4 -3 .

In order not to change the established performance of dosing pumps, the concentration of working solutions of polyphosphate is calculated based on the percentage of the content of the active substance - RO 4 -3 in working solutions of polyphosphate and previously used reagents should be the same.

It should be noted that for the preparation of working solutions of any type of phosphate, especially trisodium phosphate, chemically purified water or condensate should be used, because. when raw water is used, calcium phosphate deposits form, which leads to the drift of drainage systems.

During tests, it was noted that the decrease in the alkalinity of boiler water in boilers with alkalinity of make-up water of 0.3 mg-eq / l when switching from trisodium phosphate to polyphosphate is extremely insignificant - in salt compartments, the difference is no more than 0.2-0.4 mg-eq / l, which is lower than the accuracy of the analysis.

Our customers, who have been using PFS for several years now, are such enterprises as SE Siberian Chemical Plant, most of the Russian NPPs, energy systems JSC Kazanorgsintez and JSC Kirishiorgsintez. These enterprises speak positively about the effectiveness of the use of PFR, both in technological and economic aspects.

conclusions

1. Sodium Polyphosphate is the most concentrated of the industrially produced phosphates.

2. Estimated savings when using PPP is 6000-7000 rubles per ton of consumed TNF. When using tripolyphosphate, the savings are 900-1200 rubles/t.

3. Polyphosphate is a corrosion inhibitor. To prevent corrosion of pipelines, especially in soft water conditions, it is recommended to maintain the content of polyphosphate at the level of 2-3 kg / m 3 of water or 0.2-0.3% of the weight of running water and pH = 7-8.

4. Reduction of Ca deposits in pipelines, when using PFN, prolongs the life of boilers, prevents a decrease in the heat output of water heaters and bandwidth pipelines.

5. PFN can be used in individual heat supply private buildings and requires a single application for the heating season.

6. It should be noted that polyphosphate is non-toxic and biodegradable.

Literature

1. Yu.F. Zhdanov "Chemistry and technology of polyphosphates". "Chemistry" 1979

2. M.S. Baburina "Properties and applications of sodium hexametaphosphate". "Niigiprokhim-science" 2000

corrective treatment of boiler water at medium-pressure power plants. JSC "Permenergo", 1999

4. A.P. Vetrova “Investigation of changes in the pH of PPP solutions. OJSC "Kamteks-khimprom", 2001

Receipt.
Powdered sodium tripolyphosphate is a product of thermal phosphoric acid processing.

Chemical formula: Na 5 P 3 O 10.

Safety requirements.
Sodium tripolyphosphate is fire and explosion-proof, non-toxic.

Package.
Sodium tripolyphosphate is packed in valve or open four-, five-, six-layer paper bags, polyethylene or polypropylene bags, as well as in soft specialized disposable containers.

Transportation, storage.
Sodium tripolyphosphate is transported in covered railway wagons, closed deck vessels and covered by car. Allowed during transportation by rail pack sodium tripolyphosphate in soft specialized containers without transshipment along the route with loading and unloading at the access roads of enterprises. Sodium tripolyphosphate is also transported in bulk in specially equipped covered wagons, tank wagons.
Sodium tripolyphosphate is stored in closed containers. warehouses. Soft specialized containers are stored indoors or under a canopy.

SODIUM TRIPOLIFOSPHATE TECHNICAL TU 2148-037-00194441-02

Receipt.
Sodium tripolyphosphate technical is a product of processing of extraction phosphoric acid.

Application.
Technical sodium tripolyphosphate is intended for use in the production of synthetic detergents and a number of other industries. The type of product (A, B, C) is determined by the mass fraction of the first form of sodium tripolyphosphate.

Formula: Na 5 P 3 O 10

Safety requirements.
Technical sodium tripolyphosphate is fire and explosion-proof, according to the degree of impact on the body, it belongs to substances of the 4th hazard class.

Package.
Technical sodium tripolyphosphate is packed in four-, five-, six-layer paper bags, polypropylene bags, as well as soft specialized single-use containers. The net weight of the bag is 50 kg.

Transportation, storage.
Technical sodium tripolyphosphate is transported in covered railway wagons or gondola cars, as well as by road and water transport. Specialized tank cars, mineral wagons and cars (soda carriers) can be used as transport containers. Technical sodium tripolyphosphate is stored in closed warehouses or under a canopy.

Product shelf life.
The shelf life of the product is not limited.

Safety requirements for sodium tripolyphosphate:

LLC "Company" Plasma "®" supplies chemical products from a warehouse in Kharkov on time and at affordable prices, on favorable terms for you.

An inorganic compound consisting of a whole class of polyphosphates.

Synonyms: Sodium hexametaphosphate, Sodium polyphosphate, Graham's salt, sodium polymetaphosphate, Graham's salt, food additive E452i, SHMP.

International name: Sodium polyphosphate, Sodium hexametaphosphate.

Expanded chemical formula

Na 2 O 3 PO n PO 3 Na 2

Sodium polyphosphate is a whole class of amorphous water-soluble polyphosphates composed of linear chains of metaphosphate units. The key value in the formula is the chain n, where n - can have a different numerical value. The chains where n=2 prevail most. Laboratory identification of sodium polyphosphate is usually carried out according to the Na 2 O / P 2 O 5 ratio or the P 2 O 5 value. For sodium tetrapolyphosphate n=4, and Na 2 O/P 2 O 5 =1.3. For sodium salts of hexametaphosphate, which are also called Graham's salts, n=13...18, and Na 2 O/P 2 O 5 =1.0. For high-molecular sodium salts of polyphosphate n=20-100.

Converting sodium polyphosphate to phosphoric anhydride

Specification GOST 20291-80

According to GOST 20291-80, according to physical and chemical indicators technical sodium polyphosphate must comply with the standards indicated in the table:

This standard applies to technical sodium polyphosphate (Graham's salt) used in the textile industry to prevent the formation of calcium salts on fabrics, in the leather industry, in railway and industrial power plants for water softening, in the oil industry when drilling wells.

Production facilities in which work with the product is carried out must be equipped with supply and exhaust ventilation.

Work with the product must be carried out in special clothing in accordance with standard industry standards approved in the prescribed manner and in accordance with personal means respiratory, eye and skin protection.

Specification from imported manufacturers

Properties

A unique property of an inorganic polymer is its ability to maintain the polymer structure, both in the solid state and in aqueous solutions and melts.

Sodium polyphosphate is the most concentrated commercially available phosphate.

Low caking during storage.

Good solubility in water.

Non-toxic and biodegradable.

Inhibitor. Sodium polyphosphate slows down or prevents the crystallization of sparingly soluble salts from solution due to the formation of soluble complexes (chelates) with calcium, magnesium, barium and other metals, which are held in solution and do not precipitate.

Chelating ability. The ability to form water-soluble complexes, the stability of which is more than 1 year. For comparison: the stability of sodium tripolyphosphate complexes is from 2 to 6 months, and trisodium phosphate is even less.

Hygroscopic(capable of absorbing moisture from the air.). In air, it spreads and hydrates, turning first into pyrophosphate, and then into sodium orthophosphate.

Has good adsorption and dispersing properties.

Adsorption- is the concentration of substances on the surface or in the volume of a solid.

Dispersing properties. The property of oils to retain substances insoluble in oil: soot particles, products of incomplete combustion of fuel. In suspension, they do not allow them to precipitate.

Anti-corrosion properties. It is able to reduce iron oxide and copper scale formation on the internal heating surfaces of boilers, it allows to increase the service life of pipelines and filters due to its anti-corrosion properties.

Conducted studies show a decrease in the rate of corrosion in the water circulation systems of the enterprise from 0.6 mm to 0.1 mm per year.

To prevent corrosion of carbon steels in water, a sodium polyphosphate concentration of less than 10 mg / l is sufficient, depending on the hardness of the water ... 2-3 kg / m 3 of water or 0.2-0.3% of the weight of running water and pH = 7-8 .

Reduction of Ca deposits in pipelines, when using sodium polyphosphate, prolongs the life of boilers, prevents a decrease in the thermal conductivity of water heaters and the throughput of pipelines.

Sodium polyphosphate can be used in individual heat supply of private buildings and requires a single application during the heating season.

disadvantages

The disadvantages include:

• reduced pH value of aqueous solutions (pH ~ 7.5);
• more complex analysis of the concentration of aqueous solutions;
• reduction of alkalinity of boiler water;

The pH value of a solution of sodium polyphosphate (PPN) is 7.5-8.0 versus pH 11-12 for trisodium phosphate. To raise the pH value in the working solution of SPF, trisodium phosphate can be added in a small amount (about 50 g per 1 m 3 of the solution).

Technical application

In the chemical industry, it is used as a salt inhibitor, as a component of detergents (for example, Calgon);

Inhibitors- These are substances that slow down or prevent the crystallization of sparingly soluble salts from solution.

In the textile industry, they are used to prevent the formation of calcium salts on fabrics;

In the oil industry, technological processes drilling wells when filtering pulps and solutions;

In the pulp and paper industry, it is involved in a variety of paper manufacturing processes.

In the heat carriers of heating systems, the concentration of impurities (anions, cations, suspended particles) occurs, exceeding the limits of their solubility. As a result, they form hard scale, interfere with heat transfer and reduce the performance of boilers by 10-20% or more.

For water softening

Technical sodium polyphosphate is widely used in industrial water softening systems. It is the most active water softener with a high chelating capacity, i.e. forms stable complexes in a shorter time and at lower temperatures (20-40°C) than sodium tripolyphosphate and other phosphates.

Protection of pipelines in industrial water supply systems

Sodium polyphosphate has the ability to create soluble complexes with calcium ions and other metal ions, as a result of which calcium and iron ions are retained in solution. This is what prevents the formation of calcium and iron carbonate deposits that impair heat transfer. With an excess of calcium ions, a sparingly soluble compound Ca 5 (P 3 O 10) 2 is formed, therefore, it is necessary to strictly observe the ratio of the concentrations of polyphosphate and calcium ions (a certain excess of sodium polyphosphate is necessary).

Sodium polyphosphate is used as an inhibitor of corrosion and the deposition of calcium salts (calcium carbonates) in natural water supply systems, as well as cooling circulating industrial water supply systems.

The optimal concentration of sodium polyphosphate for carbon steel piping systems depends on the composition of the water and the speed of its movement. For the treatment of fresh waters containing chlorides, the concentration of sodium polyphosphate is most often between 0.5 and 10 mg/l. In rare cases, when fresh water contains salts or there is no water movement speed (stagnant water) - this concentration has big values and is 100 mg / l. For cases where sea water is used, the concentration of sodium polyphosphate reaches 4000 mg/l.

The advantages of using sodium polyphosphate are the absence of toxicity and inhibitory protection at low concentrations.

Processing drinking water against scale formation and against corrosion

In contrast to the treatment of industrial water, for drinking water, strict requirements for the use of inhibitors are established by sanitary standards. Sodium polyphosphate is allowed in the amount of not more than 4-5 mg/l per P 2 O 5 .

Prevention of scale in car cooling systems

Water-cooled internal combustion engines require maintenance of the cooling system. Without this, the lubricating oil can turn into soot and seize the engine.

There are requirements for water for engine cooling:

• water should be soft. The presence of hardness ions (Ca 2+ , Mg 2+) should not exceed 2 mmol/l.
• the water must be clear. The presence of turbidity in the form of suspended particles should not exceed 1 g/l.

If these requirements are not met, then scale will inevitably form in the radiator and cooling system, consisting of insoluble salts: carbonates, silicates, phosphates, magnesium salts.

In order to prevent the formation of scale, sodium polyphosphate is used. To soften very hard water, add 4 g of sodium polyphosphate to 10 liters of water. Boil the solution, then filter. After that, the water becomes soft and ready for use in the engine cooling system.

Application in the food industry

Main properties used:

• water-retaining agent (table salt enhances the effect);
• foam agent (improves foam stability);

  Create conditions for improved foaming.

• slows down chemical reactions;
• color fixative;
• stabilizer;

  Food stabilizers - form and retain the consistency, texture, shape and consumer qualities of food products. Additives with index (E-400 - E-499) preserve the consistency of products, increase their viscosity.

• emulsifier (emulsifying salt);

  Emulsifying salts include substances whose addition promotes the formation of an emulsion, but emulsifiers are not these substances themselves, but the products of their interaction with protein molecules of the substrate.

• antioxidant synergist;

  Substances that enhance the action of antioxidants, but do not have antioxidant properties.

• nutrition for yeast;
• promotes the penetration of oil filling into muscle tissue;

It is used in the production of canned and frozen meat and fish products to improve texture, as well as in the production of processed cheeses as a salt melter. Alone or in combination with other stabilizers, it is used in the production of cream, condensed milk, milk powder and cream.

minced fish

Taste, texture and appearance minced fish products are significantly improved when sodium polyphosphate is added to minced meat in an amount of 1-2% by weight of fish meat (in terms of P 2 O 5). Sodium polyphosphate is used in the production of fried fish sausages, fish sausages, smoked fish sausage, gourmet fish sticks, smoked fish pate, etc.

To obtain fish products with a good consistency, it is necessary to introduce additives in a certain order: first water, then sodium polyphosphate, then table salt.

Fish fillet processing

As a result of the treatment of freshwater fish fillets (perch, pike, trout, whitefish) with sodium polyphosphate, the outflow of juice during defrosting is reduced by an average of 60%. This is done by increasing the weight of the fillet by immersing it in a sodium polyphosphate solution before freezing. After defrosting, the fillet loses weight, which is commensurate with the weight gained during treatment with sodium polyphosphate. Thus, fillets can withstand even six re-freezings without weight loss.

The action of sodium polyphosphate on fish fillets is explained by the denaturation of meat proteins (the formation of a continuous film of denatured proteins on the surface of cuts). The resulting film prevents the juice from flowing out both during freezing and defrosting. The penetration of sodium polyphosphate deep into the meat is practically absent.

Table salt enhances the effect of sodium polyphosphate. For example, the loss of tissue juice in pikeperch fillets treated only with sodium tripolyphosphate is 1.8%. The same losses during joint processing (sodium tripolyphosphate + table salt) are 0.3%.

Fillet processing can be done by various methods: immersion, spraying, injection. Processing is carried out after stripping and washing. The concentration of sodium polyphosphate solution is 1-2.5% in terms of P 2 O 5 . For the immersion method, the residence time in the solution is 5-30 minutes. Diving requires additional equipment in the form of bathtubs. During long-term storage of the operated sodium polyphosphate solution in baths, its contamination and souring are observed. The injection method is cleaner.

Fish preserves and preserves

Sodium polyphosphate is used in the production of fish preserves and canned food to increase the moisture-binding capacity, improve the consistency of the fish and preserve the color of the product. Sodium polyphosphate promotes the penetration of the oil filling into the muscle tissue of the fish.

In the manufacture of herring preserves, before marinating in an acetic-salt solution, the herring is kept in a 10% solution of sodium pyrosulfite (in terms of P 2 O 5) for 30-60 seconds.

Seafood processing

Sodium polyphosphate is used for processing seafood: shrimp, crabs, scallops, squid.

When defrosting seafood, there is a loss of their mass. Moreover, the smaller the product, the greater the weight loss. When defrosting large shrimp, losses reach 7%, and small ones - 12%. Weight loss during defrosting also depends on the time of storage of seafood before freezing: storage in ice of small ones for 5 days before freezing increases the loss by up to 15%.

When shrimp are treated with sodium tripolyphosphate, weight loss during defrosting is almost completely eliminated.

The output of the defrosted product is 98-103% by weight of the raw material. However, in this case, there is some deterioration in color and a noticeable increase in the pH of the product, which favors its microbiological spoilage. Technological modes of processing shrimp depend on their size. Small frozen shrimp are thawed under the shower or in a solution of sodium chloride (1-2%) and sodium polyphosphate (0.5-1% in terms of P 2 O 5). The ratio of solution and shrimp is 1:1. Shrimps are kept in the solution for 24 hours at a temperature of -2°C to +2°C. Large shrimp are usually processed partially cleaned (without tail fins or without head) in a solution of common salt (1-7%) and sodium polyphosphate (2-10% in terms of P 2 O 5). Completely cleaned shrimp are kept in solution for 20-90 minutes, decapitated for 6-18 hours. After soaking in a solution of salt and sodium polyphosphate, the shrimp are washed, subjected to heat treatment and mechanical cleaning, followed by treatment with common salt and freezing.

Before freezing, scallop meat is treated by immersion for 30 seconds in a 10% solution of sodium polyphosphate (in terms of P 2 O 5).

Crab meat is treated with a solution of sodium chloride (1.5%) with sodium pyrophosphate (0.45% in terms of P 2 O 5) and sodium tripolyphosphate (0.63% in terms of P 2 O 5). Immersion of crab meat in solutions containing more than 3% (in terms of P 2 O 5) sodium pyrophosphate or sodium polyphosphate completely prevents it from turning blue, but causes an unpleasant aftertaste.

Defrosting squid fillets and carcasses in 2-4% solutions (in terms of P 2 O 5) of sodium pyrophosphate and sodium tripolyphosphate makes it possible to prevent weight loss up to 4%, and after cooking to obtain a product of a pleasant light color and pleasant texture with a yield of 20% higher than from raw squid.

cider production

Sodium polyphosphate is used in the production of ciders. Ciders are products of fermentation of fruit juices using wine yeast. They have a transparent color without sediment and foreign inclusions. The most popular is apple cider, which is also called "apple kvass". But they also produce other types of cider.

In carbonated ciders, when poured into a glass, a characteristic foam should form with the release of carbon dioxide bubbles.

To improve the stability of the foam, sodium polyphosphate (E452) is added to the cider in an amount of up to 2 g/l in terms of P 2 O 5 .