Application of soy protein isolate in lamb processing

Lamb is very nutritious, rich in vitamins and minerals such as calcium, phosphorus, iron, and low in fat and cholesterol. It is a healthy animal food. Because soy protein isolate can partially replace animal protein, it is currently the most widely used in meat processing. The addition of soy protein isolate in meat products can not only increase the protein content, but also improve the protein ratio, making the meat nutrition more comprehensive and reasonable. Utilizing the gelatinity and cohesiveness of soy protein isolate can improve the structure of meat, enhance its toughness, and have a better taste. It can also make use of its emulsification and water absorption, and prevent the precipitation of fat and water by combining with fat and water, and reduce the loss during the cooking process of meat products. 

1. The effect of soy protein isolate on the fresh-keeping effect in sheep 

Meat coating film preservation is a new technology that has emerged in recent years. The meat is smeared or soaked with a preservative to form a protective film on the surface of the meat, reducing the chance of meat contacting the outside air and preventing microbial damage. Invasion, in order to change the atmosphere environment of the meat surface, and also reduce the reduction of moisture, to achieve the effect of meat preservation. 

2. The effect of soy protein isolate on mutton water retention 

Meat products can only have a good taste and flavor by maintaining their juices. More importantly, the reduction of moisture will lead to increased costs for producers. In the meat processing process of soy protein isolate, since the protein molecules are hydrolyzed, a large number of hydrophilic groups are exposed, which has the ability to retain water for meat products, that is, water holding capacity. 

Some studies have shown that the mixed solution obtained through the ratio has better water retention effect on mutton than using soy protein isolate alone. Some scholars have studied the effects of soy protein isolate, maltodextrin, NaCl and hydrocolloids on the water holding capacity of mutton. The lamb leg lean meat is washed and divided, and then the soy protein isolate, maltodextrin, NaCI, carrageenan, and sodium alginate are injected into the meat. After standing still, the water holding capacity and yield are measured. The best formula, reaction time and injection temperature are screened out through orthogonal experiments. Tests have shown that 2% soy protein isolate + 2% maltodextrin + 1.8% NaCI + 0.3% carrageenan + 0.2% sodium alginate, dissolved in distilled water at 20°C and reacted for 1 hour, is useful for improving the water holding capacity and yield of lamb The effect is best. 

3. Application of soy protein isolate in the processing of recombinant minced mutton rolls 

During the processing of mutton, a large number of by-products, such as tendons, mechanically deboned meat, fat, etc., will be produced. These by-products are often not used well, resulting in a waste of resources. Reorganized meat technology has developed rapidly in developed countries such as Britain and the United States, and has been widely used in meat products such as sausages, steaks, pork chops, pies, etc., which has greatly increased the utilization rate of minced meat. my country's minced meat recombination technology has also developed rapidly in recent years. Using soy protein isolate, casein and other homologous or heterologous protein groups to polymerize and covalently cross-link the reaction field, improve the gel capacity and gel stability of the protein, and can recombine the minced meat. This method also requires the use of TG (transglutaminase) to catalyze the acyl transfer reaction within or between protein molecules to produce covalent crosslinks. Soy protein isolate, casein and TG have a synergistic effect, so that the minced meat forms a dense viscose network structure. 

The process of reorganized minced lamb rolls is as follows: 

Some scholars use minced mutton as raw material, and use TG to cross-link at low temperature to polymerize small molecular proteins into macromolecular proteins and make mutton stick to form mutton rolls. At the same time, non-meat protein is added to replace fat to produce low-fat Healthy mutton products turn waste into treasure. 

Tests have shown that adding TG alone can not significantly improve the bonding performance of meat chunks, and TG combined with casein, starch and soy protein isolate can significantly improve the bonding capacity of meat chunks. Among them, the concentration of soybean protein isolate is 0.8%, and the shape retention is not ideal if the concentration is too low or too high. 

In 2011, China's Inner Mongolia Agricultural University conducted a research on the reorganization of chilled minced lamb. Tests have shown that there is a synergistic effect between non-meat protein and TG. The best ratio is TG 1.2%, soy protein isolate 0.7%, and casein 0.3 %, 0.9% ovalbumin, which can achieve a better restructuring effect. 

4. The application of soybean protein isolate in lamb flavor base 

Meat flavor base is a technology that utilizes Maillard reaction to produce meat flavor. Research began in my country in the 1980s. Meat flavor base material has low cost, good stability, convenient use and strong and vivid smell, and has a broad market in the food field. It can be used in instant seasonings, meat products and condiments, etc. Among meat flavor base materials, chicken and beef flavor base materials are currently used more frequently, and lamb flavor base materials are relatively few. 

In 2014, Ningxia University in China conducted a systematic study on the mutton flavor base material, using soybean separation proteolytic solution as the basic raw material, adding various amino acids and oxidized lamb fat, and finally preparing a lamb flavor base material that meets the popular taste. 

Soy protein isolate has a high protein content. After protease hydrolysis, amino acids needed for Maillard reaction to produce meaty substances are obtained, and then amino acids and reducing sugars that need to be supplemented are added for Maillard reaction to finally obtain lamb flavor substances. The specific test results are as follows: 

Using alkaline protease and flavor protease as tool enzymes for enzymatic hydrolysis of soy protein isolate, the final determination of the protein content of soy protein isolate was 84.22%. Apply the corresponding surface method to optimize the optimal reaction conditions for the two enzymes: the addition amount of alkaline protease enzyme is 4%, the substrate concentration is 5%, the temperature is 500C, pH=11, the reaction time is 5h, and the maximum degree of hydrolysis obtained after optimization is 18.36% The reaction conditions of the flavor protease are as follows: the amount of enzyme added is 3%, the substrate concentration is 4%, the temperature is 55℃, pH=6, the reaction time is 5h, and the maximum degree of hydrolysis obtained after optimization is 14.21%. The degree of hydrolysis of soy protein isolate can be increased to 38.67% by using the secondary enzyme method. 

The optimal formula of Maillard reaction materials and reaction conditions is: temperature 105℃, time 50min, pH=6, soybean separation proteolysis solution 40mL, cysteine 1.59, thioine 0.49, glycine 0.5g, arginine 0.6g, alanine 0.5g, proline 1g, aspartic acid 2g, glutamic acid 2g and glucose 3g. The mutton flavor base liquid obtained under these conditions is yellow, clear and transparent, with strong aroma and long-lasting aroma. 

The oxidation conditions of sheep fat are: reaction time 50min, reaction temperature 115℃, stirring speed 250r/min, single factor experiment confirmed that the addition amount of sheep fat oxide is 0.4g. 

With the continuous in-depth research on the nutritional value and functional properties of soy protein isolate, it will be more widely used in the processing of mutton and other meat products. In the specific application process, the product characteristics, process requirements, formula design and economic benefits of various meat products should be fully considered to give full play to the role of soybean protein isolate.