Application of soy protein in meat products

Foreword: Soy protein isolate has been widely used in meat products. Although my country’s protein isolate production capacity has developed rapidly, production technology has not improved significantly, product quality has stagnated, and multi-variety, multi-functional, and serialized products have not yet been formed. The high-nutrition and high-value-added product characteristics of soy protein have not been fully reflected, and the market price has been in a downturn. Moreover, the domestic protein isolate has a single variety with little functional difference, and the product quality cannot meet customer requirements. Hundreds of foreign soybean protein isolate products can be produced, which are widely used in various industrial fields. Because of the variety and good quality of foreign products, although the price is much higher than that of domestic products, they still occupy about 1/3 of the domestic market.

The production process and technology of soybean protein isolate abroad have developed rapidly, and a series of formula technologies have been formed from extraction methods to modification methods. According to the application field and product performance of the product, the extraction method and modification method are different. The products thus produced are widely suitable for the different needs of meat, dairy products, light chemical industry and other fields, and truly reflect the high nutrition and high value-added characteristics of soybean protein.

1. Soy protein plays an important role in meat products

Because soy protein has the functional properties of protein, it is widely used in food processing. In recent years, with the development of social productivity, people's living standards have been improved, the consumption of meat products has reached an unprecedented height, and various meat products have also entered the market in accordance with the needs of consumers. Soy protein has been paid more and more attention by the meat processing industry due to its important functional properties in meat processing. The following characteristics of soy protein are mainly used in meat processing.

1) A cost-effective protein source with enhanced nutrition

Soy protein has been widely used in meat products because of its low price and good protein quality. Adding soy protein to enema, ham and other products can not only increase the protein content, but also improve the ratio of protein to make protein The nutrition is more comprehensive and reasonable.

2) Seasoning effect in meat products

Soy protein contains a small amount of fatty acids and carbohydrates, which will produce a unique bean aroma after heating, and meat products; sometimes raw meat (such as fish) or auxiliary materials and some unpleasantness caused by processing techniques (such as sterilization) Odor may arouse consumer disgust. The unique aroma of soy protein has a masking effect on the above smell, so soy protein has a certain flavoring effect on meat products.

3) Soy protein can improve the structure of meat products

Soy protein has good gel properties and bonding properties, which can be used to improve the structure of the product, enhance the elasticity and hardness of the product by adding soy protein in the processing of meat products, and make the structure of the product compact and taste better. , The sensuality is stronger.

4) Utilize the emulsifying properties of soy protein to solve the problem of water and oil in meat products

Water and oil are one of the most common problems in the processing, production and storage of meat products. The use of soy protein has the characteristics of both hydrophilic and lipophilic groups, and has a good affinity for water and oil, and can absorb Water and oil form a relatively stable network structure, so that the water and oil in the meat products will not be freed, and no water and oil will be emitted during the process of processing and storage.

2. Some performance indexes of soybean protein isolate used in meat products

1) Water retention

In addition to the absorption of water, soy protein isolate also has the ability to retain water during processing. Its water retention is related to viscosity, pH, ionization strength and temperature. Salt can enhance the water absorption of protein, but it weakens water retention. The highest water retention capacity is 14g water/g protein at pH7 and 35～55℃.

2) Emulsification

Emulsification refers to the ability of mixing oil and water to form an emulsion. The emulsion of fat and water is not easy to stabilize because of the positive free energy generated by the tension on the interface. Protein has the characteristic structure of affinity of emulsifier, and contains both hydrophilic group and lipophilic group in protein molecule. In the oil and water mixture, the tendency of protein, oil and water interface. Therefore, when soybean protein is used in food processing, it accumulates at the oil-water interface to reduce its surface tension and promote the formation of oil and water emulsions. After forming an emulsion. The emulsified oil is stabilized by the protein accumulated on its surface, forming a protective layer. This protective layer can prevent oil accumulation and destruction of the emulsified state. This shows that soy protein not only has emulsifying properties, but also has strong stability. Soy protein isolate is a surface active agent, it can reduce the surface tension of water and oil, but also can reduce the surface tension of water and air, so it is easy to form a more stable emulsion, and the emulsified oil is accumulated by the protein on the surface of the oil. Stable to form a protective layer. In the production of grilled food, frozen food and soup food, there have been research reports on adding a large amount of soy protein isolate as an emulsifier to stabilize the product state.

3) Oil absorption

The oil absorption of soy protein isolate is manifested in two aspects: (1) It promotes fat absorption. The role of soy protein isolate in absorbing fat is emulsification. When protein isolate is added to meat products, it can form an emulsion gel to prevent fat from moving to the surface, thereby promoting fat absorption and fat binding, thereby reducing meat product processing The loss of fat and juice during the process helps maintain the stability of the appearance. Oil absorption increases with the increase of protein content, and decreases with the increase of pH. (2) Control fat absorption. Soy protein isolate can also play a role in controlling fat absorption under different processing conditions, such as preventing excessive absorption of fat during frying. This is because the protein is denatured by heat and forms an oil layer on the surface of fried noodles.

4) Foaming

Foaming refers to the increase in volume of soy protein during processing. Foam is made up of air dispersed in liquid phase and semi-solid. It is composed of many groups of air wrapped in a layer of soluble protein film activated on the liquid surface, which reduces the surface tension of air and water. Bubbles are caused by the separation of the elastic liquid film or semi-solid film to prevent the merger of the bubbles. Utilizing the foaming properties of soy protein can give food a loose structure and good taste.

5) Stickiness

The viscosity of protein refers to the internal friction that appears when the liquid flows, also known as fluidity. It is important to adjust the physical properties of food. The viscosity of protein solution is comprehensively affected by various factors such as protein molecular weight, friction coefficient, temperature, pH, ionic strength, processing conditions and so on. These factors can change the morphological structure, state of association, hydration, swelling and viscosity of protein molecules. After soy protein isolate undergoes alkali, acid or heat treatment, its swelling degree and viscosity increase. The surface viscosity of the soy protein solution increases exponentially with the increase of the protein concentration, and is related to the swelling degree of the sample. When the protein is heated to 80℃, the viscosity will increase, and the viscosity will decrease when it exceeds 90~C. When the pH is 6 to 8, the protein structure is the most stable and the viscosity is the largest; when the pH exceeds 11, the viscosity decreases sharply because the protein binding is destroyed.

6) Solubility

Some of the polar parts of the soybean protein molecule can be ionized, such as amino and hydroxyl groups, so that the polarity and solubility can be changed by changing the pH value. When the pH value is 0.5, about 50% of the protein is dissolved; when the pH value of the system reaches 2.0, about 80% of the protein is dissolved. As the pH increases, the solubility of the protein decreases, until the pH value is within the isoelectric point range of 4 to 5, the protein solubility tends to the minimum, about 10%. Then, as the pH value gradually increased, the solubility of the protein increased rapidly again. When the pH value is 5.6, the protein solubility can reach more than 80%, and when the pH value is 12, the maximum solubility can reach more than 90%. According to the dissolving properties of soy protein, the isolated soy protein can be added to the salted salt water through injection and rolling to make the salt water evenly diffuse into the muscle tissue and cooperate with the salt-soluble meat protein to maintain large pieces of meat such as ham and corned beef. The integrity of the product improves the yield.

Soy protein isolate (SPI) has a broad application prospect in the field of food processing. The main components of soy protein isolate are 7S and 11S globulins. Therefore, the solubility of soy protein isolate is very low, especially in the isoelectric point region of soy protein at pH 4~5, which limits the range of use of soy protein isolate. Therefore, the solubility of soy protein isolate is improved, and it becomes soy. Problems that need to be solved urgently in the practical application of protein isolates.

7) Gelation

When heated, soy protein isolate has the ability to form a gel, and the gel-forming ability is one of the functional characteristics of soy protein isolate. Gelability refers to the ability of proteins to form limb-like structures. It makes the soy protein isolate have higher viscosity, plasticity and elasticity. It can be used as a carrier for water as well as a carrier for flavors, sugars and other complexes. This feature is extremely beneficial to food processing. Soy protein dispersion material can be heated, cooled, dialysis and alkali treatment to obtain gel. Its formation is affected by the concentration of solids, temperature and heating time, refrigeration, the presence or absence of salts, sulfhydryl compounds, sulfites or lipids. The higher the protein content, the easier it is to make a firm, tough, elastic hard High-quality gel, and the protein content is less than 7%, can only be made into soft and fragile gel. The protein dispersion should be at least more than 8% to form a gel. The gel made of llS globulin is firmer than the gel made of 7S globulin and is easier to restore to its original state, because their globulins are different in sensitivity to heat denaturation.

8) Water attached

Soy protein contains many polar groups along its peptide chain backbone. Due to the attraction between these polar groups and water molecules, hydration is prone to occur when protein molecules come into contact with water molecules. The shape of protein molecules is not regular, and the distribution of polar groups on the surface is also difficult to be uniform. Therefore, the hydration film on the surface of protein molecules is not uniform, and more water molecules are adsorbed on the surface where the polar groups are concentrated. ; On the contrary, there will be less adsorption of water molecules. When adding soy protein isolate to meat products, the water absorption and water retention of the protein becomes an important issue. It can retain moisture even when heated, which is essential for meat products. Due to these characteristics of soy protein isolate, it is currently widely used in the production of meat products.

3. How to use soy protein:

Protein isolates have been widely accepted by most manufacturers in various combined use methods, especially the chopper method is the most popular, mainly because of its multiple functions and the more flexible manufacturing process. In terms of its application, compare the advantages and disadvantages of the following application methods.

1) Rehydration method: first put the soy protein isolate with 4 to 5 times ice water into the chopper and chop at high speed for 1 to 2 minutes, then add lean meat, ice water, polyphosphate and salt. Chop and mix at high speed for 2 minutes to extract salt-soluble meat protein. At this time, the temperature is just controlled at 2～4℃, because this temperature is the most appropriate temperature for the extraction of salt-soluble protein. After the salt-soluble protein is extracted, add fat and fat. The ice water, continue to chop and mix for 2 minutes, at this time the temperature should be about 6 ~ 8 ℃, this is the most common method.

2) Gel method: first use 4 times water of the soybean protein isolate, use a chopper to emulsify it at high speed, and then wait for use. Then add it to the lean meat according to the required amount and chop. The other steps are the same as the above-mentioned water-attached method. The gel method can be stored in a refrigerator for later use. Although the separated protein can be stored in the refrigerator for 2 to 3 days, it is prone to rancidity and easy growth of bacteria. It is recommended to use it up as soon as possible.

3) Emulsified oil method: using protein isolate to produce emulsified oil raw materials, chicken skin, fat fat, butter, soybean oil and pig skin can be used as raw materials. The most important way to make emulsified oil is to use a chopper to add water to the protein isolate, then add oil, and continue to chop into emulsified oil before use. In the production process of emulsified products, emulsified oil is added after the salt-soluble meat protein is extracted, which is more complicated than the gel method. However, proper processing and addition of emulsified oil can not only reduce product costs, but also increase product fragrance and flexibility.

4) Dry addition method: This method is simple to use. First add the protein isolate to the lean meat, chop it slightly, add 4 times the water, chop for 1 to 2 minutes, then add polyphosphate, ice water and salt, and continue to chop. Stir for 2min, the procedure is the same as above. However, there is also a method of directly adding dry matter such as protein isolate and starch to the final chopping. Although this method is convenient, it is not recommended to use this method because the soy protein isolate is not fully attached to water and its function is not fully developed. The product will be softer under the same formula, and the water absorption and oil retention will be poor. Therefore, this method is not recommended. . Another example: adding soy protein isolate and lean meat together, but without water, this effect can not properly attach water to the soy protein isolate, but also affects the extraction of salt-soluble protein, and the manufactured product will be softer. Therefore, the water attachment and addition steps also affect the quality of the final product.

Due to the influence of the performance of the protein isolate itself, a certain reversible reaction will occur when it encounters salt, which will weaken its emulsification, oil retention and water retention properties. Therefore, no matter what method is used to produce emulsified meat products, in order to maximize the functionality of soy protein isolate, soy protein isolate must be completely attached to water.

4. Summary:

The strong water and oil retention of soy protein reduces the amount of lean meat, increases the amount of water and fat, increases the yield of the product, improves the tissue state and taste of the ham sausage, and reduces the production cost.

After adding soy protein, the cooking time of the ham sausage is shortened, therefore, the cooking loss is reduced, the shrinkage of the ham sausage is reduced, the tissue structure is improved, and the quality of the ham sausage is improved.

The addition of soy protein to ham sausage must be carried out before curing to prevent the salt resistance of soy protein. It can be added to meat emulsion through pre-hydration to increase the effect of soy protein.

Soy protein isolate (SPI) is used in meat products, not only as a non-functional filler, but also as a functional additive to improve the texture and flavor of meat products, and make full use of undesirable or incomplete corner raw meat. The price of soy protein isolate itself is relatively high, but it is applied to higher-grade meat products. Because of its strong functionality, even if the usage amount is between 2% and 2.5%, it can retain water, fat, and prevent gravy separation. , Improve quality, improve taste, and extend shelf life at the same time.

In food processing, as a food additive, soy protein isolate can play a complementary role in amino acids and is a functional food. It can improve people's health and has high digestibility and utilization rate. When mixed with other foods, it can significantly improve the nutritional value of the original food. It can completely replace animal protein. The content of 8 kinds of amino acids is relatively close to the needs of human body. Methionine is slightly insufficient. It is similar to meat, fish, eggs, milk, etc. It is a full-price protein and has no side effects of animal protein, such as induction. Obesity, cardiovascular disease, hypercholesterolemia and other diseases are a good source of human protein, and it is safe and reliable and contains fewer microorganisms. Soy protein isolate has water retention, emulsification, elasticity and cohesiveness, and strong foaming properties. It can be used in foods such as meat products, cakes, bread, candy, and beverages, and its tissue has similar properties to meat. It can not only be made into food alone, but also be made into various foods with vegetables or meat, etc. The food has good color, fragrance and taste, and can be adjusted according to consumer tastes, and the nutritional content can be adjusted according to different consumer groups. With the advantages of fortification, it can provide new foods that are more nutritious and tasteful than traditional foods.