Preparation method of complex phosphate_Industrial additives

Background and overview^[2]

Complex phosphate, also known as polyphosphate, is a mixture of sodium pyrophosphate and sodium tripolyphosphate. When added to shrimp mince, it can be used as a freezing denaturation inhibitor for shrimp protein, and can also enhance the elasticity of shrimp mince products. effect. The mechanism of action of phosphate can be summarized as follows: ① The addition of phosphate can increase the pH of the muscle, moving the pH away from the isoelectric point of the protein and moving toward a neutral or alkaline direction, thus improving the water retention and elasticity of the product; ② Phosphate It can increase the ionic strength of meat, increase the dissolution rate of salt-soluble protein, and promote the formation of a special network structure between salt and sarcoplasmic protein to improve water holding capacity; ③ Phosphate can chelate certain kinkabo of meat protein Special ions, such as calcium and magnesium ions, release carboxyl groups. Due to the electrostatic repulsion between free carboxyl groups, the protein molecular structure relaxes, significantly increasing the absorption rate of water molecules, and achieving the purpose of improving gel properties; ④ Phosphate In particular, polyphosphate is a polyvalent anionic compound. Because it has high ionic strength at lower concentrations, the solubility of actomyosin increases within a certain ionic strength range and turns to a sol state, thus increasing the amount of meat. Water holding capacity of products, etc. The enhancement effect of polyphosphate on the elasticity of surimi is considered to be due to its significant increase in the solubility of myofibrils when coexisting with salt, inorganic substances, etc.

Preparation^[1][3]

Report 1,

Weigh 5kg of food-grade sodium tripolyphosphate, sodium pyrophosphate, and sodium hexametaphosphate according to a mass ratio of 7:2:1, and place them in a small stirring kettle. , open the stirring kettle, spray 500g of food-grade phosphoric acid with a mass fraction of 85% into the kettle, then spray 100g of a 50% mass fraction of potassium chloride solution, 100g of a 50% mass fraction of calcium chloride solution, and 200g of a 50% mass fraction of calcium chloride solution. 50% ferric chloride solution. Then keep stirring for 10 minutes to obtain the composite phosphate.

The specific proportion of composite phosphate after the reaction is: 60% sodium tripolyphosphate (degree of polymerization 3), 15% sodium pyrophosphate (degree of polymerization 2), 3% sodium hexametaphosphate (degree of polymerization ≥ 6), 15% Sodium hydrogen phosphate (degree of polymerization 1), 7% disodium hydrogen phosphate (degree of polymerization 1).

Report 2,

Add potassium chloride containing K₂O₅9.3%; Cl^–46.98% to P₂O₅ 25.11% phosphoric acid solution, stir evenly in the batching tank, and adjust the H₃PO₄/KCl molar ratio to 1.3. Transport the material liquid to the spray drying tower for atomization, and use high-temperature air for heating. Control the feed volume of the atomizer and the hot air inlet temperature. Check that the inlet temperature of the spray drying tower is 235°C and the outlet temperature of the spray drying tower is 185°C. At this temperature, potassium chloride and phosphoric acid complete the metathesis reaction, and the generated hydrogen chloride gas enters the water scrubber with the tail gas to be washed to produce hydrochloric acid. The material at the bottom of the tower flows into the cooling tank, where it is cooled and crystallized to produce composite phosphate.