1.Characteristics of Phosphate and Its Function in Food Processing

There are two main functions of phosphate in food processing: one is as a quality improver to improve the structure and taste of food; the other is to be used as a mineral nutrition fortifier.

The role of phosphates in food processing is mainly based on the following properties of phosphates:

1). Buffering effect: The pH value of phosphate ranges from moderately acidic (PH~4) to strongly alkaline (PH~12). When different phosphates are matched in different proportions, the pH value can be stabilized at PH4.5 - Different levels of buffer between 11.7. In the pH range of most foods (PH3.5-7.5), phosphate can be used as an efficient pH regulator and pH stabilizer, making food taste more delicious. The strongest buffering effect is orthophosphate, and for polyphosphate, the buffering capacity will decrease as the chain length increases.

2). Water-holding effect: Polyphosphate is a highly hydrophilic water-retaining agent, which can well stabilize the water contained in food. The quality of its water holding capacity is related to the type of polyphosphate, the amount of addition, the pH value of the food, the ionic strength and other factors. For meat products and seafood, the best water-holding capacity is pyrophosphate, followed by tripolyphosphate. As the chain length increases, the water-holding capacity of polyphosphate will weaken.

3). Polyanion effect: Polyphosphate is a polymeric dielectric and has the characteristics of inorganic surfactants, which can disperse insoluble substances in water or form a stable suspension to prevent the suspension from adhering and coagulating. Polyphosphates are widely used in the phosphorylation of starch, the dispersion of pigments, and the emulsification of food (emulsion) because the hydrosol of the protein can form a film on the fat globule, so that the fat can be dispersed in the water more effectively. products, ice cream, salads, sauces, etc.) and as a dispersion stabilizer for sausages, minced meat products, and surimi products. For linear polyphosphates, its emulsifying and dispersing ability increases with the increase of chain length.

4). Chelation: Polyphosphate is easy to form soluble complexes with metal cations in the solution, thereby reducing the hardness of water and inhibiting the oxidation, catalysis, discoloration and decomposition of vitamin C caused by metal cations such as Cu2+ and Fe3+. , to prevent and delay fat oxidation, prevent meat, poultry, fish spoilage, maintain the color of the purpose, in order to extend the shelf life of food.

The chelation of polyphosphates depends on chain length and pH. Generally speaking, long-chain polyphosphates have strong chelating ability for light metal ions, which increases with the increase of pH value; short-chain polyphosphates have strong chelating ability for heavy metal ions, but with the increase of pH value increased, chelation weakened.

5). Protein effect: Phosphate has an enhancing effect on protein and prion protein, so it can improve the hydration and water holding capacity of meat products, improve the permeability of water, promote the softening of food, improve the quality of food, and maintain the flavor of food. . At the same time, phosphate in dairy products can prevent the coagulation of milk when heated, and prevent the separation of casein and fat moisture.

6). Leavening effect: Acidic phosphates (such as sodium acid pyrophosphate, calcium hydrogen phosphate) are usually used as the leavening acid of the leavening agent for baked products, and react with bicarbonate to provide the carbon dioxide gas required for the baking process.

7). Anti-caking effect: Tricalcium phosphate is commonly used as an anti-caking agent to improve the free-flowing properties of powdered or hygroscopic foods. Tricalcium phosphate has a large specific surface area and can bind more water; and its special spherical crystal structure can produce a "ball effect", so that the powder has good free-flowing properties.

8). Extend the shelf life of food: Polyphosphate can enhance the storage stability of food and prolong the shelf life of the product. This effect is mainly based on: (1) PH regulating effect; (2) bacteriostatic effect: microbial cell growth must depend on divalent metal cations, especially Ca2+ and Mg2+, and phosphate can chelate with these metal cations, and it It can reduce the stability of the cell wall during cell division, and also reduce the thermal stability of many cells, thereby effectively inhibiting bacterial growth. The antibacterial effect of polyphosphate is related to its type (chain length), content, pH value, salt content, nitrite content and other factors. In general, as the chain length increases, the bacteriostatic effect increases.

9). Mineral nutrition enhancement: calcium phosphate, magnesium phosphate, iron phosphate and zinc phosphate are often used as mineral enhancers in food processing. Adding iron phosphate and zinc phosphate to gastric juice can enhance the biopharmaceutical effect of gastric juice because of its better solubility, and will not promote the occurrence of natural oxidation.

2.Application of Phosphate in Food

1). Application in the processing of meat products and poultry meat products:

1.1 In order to improve the quality of meat products, phosphate is usually added in the processing of meat products, and its functions are:

a. Improve the cohesiveness of meat products and improve the slicing performance of meat products;

b. Improve the water-holding capacity of the meat, so that the meat products can still maintain their natural moisture during processing and cooking, reduce the loss of nutrients in the meat, preserve the tenderness of the meat products, and improve the yield;

c. Control the pH value of meat products in the most suitable range for protein swelling and produce the best color of meat products;

d. Improve emulsification performance and emulsification stability, and effectively prevent the separation of fat and water;

e. Block metal cations, delay the oxidation reaction in the processing of meat products, can effectively reduce the speed of product rancidity, inhibit the decolorization and rancidity of meat products, and prolong the shelf life of meat products;

f. Improve the processing performance of meat products and increase production efficiency.

1.2 The water-holding capacity of meat generally refers to the water-holding capacity of the meat and the water added to the meat during processing. The water-holding capacity is directly related to the texture and yield of meat products. Adding phosphate can effectively improve the quality of meat products. water holding capacity.

How to use phosphate and other additives reasonably without affecting the flavor of meat products, maximize the water holding capacity and cohesiveness of meat products, and reduce the cooking loss of meat products, has always been an important topic in the research and development of meat products. .

1.3 Reasonable use of phosphate in meat processing:

In practical applications, the appropriate type and amount of phosphate should be selected according to the type of meat products, texture requirements, production process, raw materials, etc., combined with the characteristics of various phosphates.

In meat products with pyrophosphate added, the natural water retention capacity of muscle protein can be restored and enhanced, and polyphosphate can be quickly converted into pyrophosphate under the action of muscle enzymes, so the same effect can be achieved.

Although pyrophosphate has the best water retention effect, its solubility is too poor, so it cannot be used alone in most cases, but is often used in combination with long-chain polyphosphate or potassium phosphate with better solubility. In addition, in order to exert the synergistic effect between various phosphates and phosphates and other additives, various compound meat product improvers are often used.

a. For sausages and minced meat products, pyrophosphates and medium-chain polyphosphates are usually used, which are added in the form of dry powder during chopping. The pH of the complex phosphate used is generally around 7, and sometimes complex phosphates with a pH higher than 9 are used.

b. The complex phosphate used for saline injection must meet the following requirements: 1) good solubility in ice brine; 2) high dissolution rate; 3) good stability in ice brine.

The pH value of the complex phosphate used is generally 8.5-9.5. In order to achieve the best muscle protein activation effect when preparing ice saline for injection, it is best to dissolve phosphate in ice water first, and then add salt. This order cannot be reversed.

c. The addition amount of mixed phosphate is generally 0.1-0.4%, but the amount should be strictly controlled when using. If the added amount is too high, the original flavor of the meat will be damaged, and the color development will be affected due to the increase of pH value.

2). Application in seafood processing:

2.1 Phosphate is widely used in the processing of seafood, especially frozen seafood, as a water-retaining agent, PH regulator and antifreeze agent with excellent performance. Its functions are:

a. Effectively improve the water holding capacity of seafood, make the gravy richer, and effectively maintain nutrients and moisture;

b. Inhibit the oxidation of fat and effectively prolong the shelf life of seafood;

c. Reduce droplet loss after thawing and reduce cooking weight loss;

d. Maintain the natural color and flavor of seafood;

e. Synergistically synergistic with carbohydrates, effectively preventing surimi protein from freezing and denaturation.

2.2 When processing frozen shrimp, fish and shellfish, the products are usually immersed in a 3-10% complex phosphate solution (temperature less than 10°C). The type, size and fishing time of seafood are determined.

The following factors should be considered when choosing a complex phosphate for immersion:

a) Can effectively improve the water holding capacity of seafood;

b) Good solubility in ice water;

c) dissolves rapidly in ice water;

d) Good stability in ice water.

The PH value of the compound phosphate used is generally higher than 9. 2.3 The compound phosphate added to the frozen surimi is mainly sodium pyrophosphate, sodium tripolyphosphate and sodium hexametaphosphate, and the added amount is 0.1-0.3% of the surimi .

3). Application of Phosphate in Pasta Products

3.1 Application in bakery products: Acidic phosphates (such as sodium acid pyrophosphate, calcium hydrogen phosphate) are usually used as the leavening acid of leavening agents for bakery products, and react with bicarbonate to provide the required carbon dioxide for the bakery process gas. Different phosphates have different dough reaction rates (RORs), and phosphates can be reasonably selected according to the expected baking effect (bulk volume, pore structure, taste). In addition, phosphates can also be used as flour conditioners, dough improvers, buffers and yeast nutrients.

3.2 Phosphate is widely used in the processing of instant noodles and ordinary noodles as a noodle quality improver. Its main functions are:

a. Increase the degree of starch gelatinization, increase the water absorption capacity of starch, increase the water holding capacity of the dough, and make instant noodles rehydrate quickly and easily brew;

b. Enhance the water absorption and swelling properties of gluten protein, improve its elasticity, make the noodles smooth and chewy, resistant to cooking and foaming;

c. The excellent buffering effect of phosphate can stabilize the pH value of the dough, prevent discoloration and deterioration, and improve the flavor and taste;

d. Phosphate can be complexed with metal cations in the dough, and has a "bridging" effect on the glucose group, forming the cross-linking of starch molecules, making it resistant to high temperature cooking, and the noodles fried at high temperature can still be maintained after rehydration. Viscoelastic characteristics of starch colloids;

e. Improve the finish of noodles;

4). Application in dairy products:

Phosphate is used as stabilizer and emulsifier in UHT-sterilized milk, cream products, condensed milk, milk powder, coffee mate, milk beverages, cheese products, and its functions are:

a. Buffering and pH stabilization;

b. Interaction with protein: disperse food ingredients, stabilize the emulsification system, enhance the ability of casein to bind water, and effectively prevent the separation of protein, fat and water;

c. Chelating polyvalent metal ions, which greatly reduces protein agglutination and precipitation during heating and storage, thereby improving the thermal stability and storage stability of milk. And can effectively delay the occurrence of lactose coagulation.

5). Phosphate is also widely used in the following food processing fields:

â—Ž Beverage: used as acidity regulator, stabilizer and mineral nutrition enhancer;

â—Ž Potato products: used as stabilizer and color retention agent;

â—Ž Rice products: improve the elasticity of the products and improve the taste of the products;

â—Ž Seasoning and instant soup: stabilizer, acidity regulator;

â—Ž Hygroscopic powder food: prevent caking and improve its free flow performance;

â—Ž Starch products and modified starch;

â—Ž Baby food, functional food: mineral nutrition fortifier.

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