Application of transglutaminase in meat products
â–¡ Zhang Jianguo Liu Xiaozeng
Transglutaminase, a glutamine transaminase, is a very good protein modifier that catalyzes intramolecular and intermolecular cross-linking of proteins, and the linkage between proteins and amino acids. Hydrolysis while improving the function and properties of the protein. China's total meat production ranks first in the world, but the amount of meat products only accounts for 6% of the total. From the perspective of 40% to 50% of the total meat production in developed countries, it shows that China is processing meat. There is still a great potential for field meat, and transglutaminase is an excellent meat processing improver with great potential for use in meat products.
Glutamine transfer
Transglutaminase is widely distributed in natural organisms. Transglutaminase was first discovered by the Karak people in the liver of guinea pigs. It has been continuously studied that transglutaminase is also present in microorganisms, plants and other animals.
Animal Sources Transglutaminase is present in almost all tissues and organs of mammals. From the 1960s to the 1990s, the extraction of transglutaminase from the liver of guinea pigs resulted in high prices due to the small number of sources and the complicated purification process.
Plant Sources In 1987, Escarson et al. found that transglutaminase was present in peas. Researchers have found that transglutaminase is also present in many plants such as potatoes, Jerusalem artichoke, and corn. Some researchers have conducted in-depth research on the transglutaminase extracted from soybean, but found that the separation and purification process is very complicated, and the enzyme yield is relatively low. So far, plant-derived transglutaminase has not been used for commercial production.
Microbial sources In 1989, Itan et al. first isolated and purified transglutaminase from the porch spirulina. Subsequently, the researchers found the presence of transglutaminase in other microorganisms, and carried out a large number of microbial fermentation tests, enzyme purification separation tests, etc., and made great progress. Compared with animal-derived transglutaminase, microbial-derived transglutaminase is an extracellular enzyme that can be directly secreted in culture medium. Separation and purification are relatively easy. The raw materials used for fermentation are low in price and short in production cycle. The most promising for large-scale industrial production.
Physicochemical properties of transglutaminase
Different physicochemical properties of transglutaminase from different sources The molecular weight of transglutaminase in animal liver is between 70 and 90 kDa, which needs to be activated by ion activation of calcium. The active center of the enzyme is cysteamine. Ammonium acid residue site. Among the animal-derived transglutaminase, the transglutaminase study of the guinea pig liver is the most in-depth study. The study found that the molecular weight of the enzyme is about 90KDa, so that the enzyme reaction requires calcium ion deactivation, the substrate specificity is strong, and the enzyme contains more The cysteine ​​residue results in poor thermal stability, and its enzyme activity is only 40% of the residual activity at 50 ° C for 10 min.
Compared with the source of the animal, the microbial-derived transglutaminase has more excellent properties: first, it has a lower molecular weight, a molecular weight of 23,000 to 45,000, a majority of about 40,000, and a high degree of crosslinking catalyst; Stronger heat resistance, derived from S. The transglutaminase of mobaraensis has the same activity even at 10 ° C for 10 min, even at 50 ° C, the enzyme still has 74% activity for 10 min; the third is strong acid and alkali resistance Fourth, the presence or absence of calcium ions has little effect on the activity of the enzyme. This property is very important because most proteins are easily chemically reacted with calcium ions, leading to protein precipitation. Fifth, transglutaminase is resistant to high temperature and pressure. The pressure of the surrounding environment has little effect on the biological source of transglutaminase.
Transglutaminase Reaction Mechanism Transglutaminase catalyzes three different chemical reactions: one is the catalytic reaction of the amide group between the γ-carboxy amide group and the primary amine of a glutamic acid residue in a protein or polypeptide. Second, when the γ-amino group of the lysine residue in the protein is an acyl acceptor, the protein can form an ε-(γ-glutamic acid) lysine isopeptide bond (G-L bond) in or between molecules. Crosslinking proteins, changing the solubility of proteins, cross-linking various protein molecules, thereby improving the texture properties of products, such as elasticity, etc. Third, when there is no primary amine in the protein, The aminoamidase deprotects the amino group with water as the acyl acceptor.
The reaction of transglutaminase with meat-derived proteins Myofibrils are an important component of meat. Myosin and actin are the most important components of myofibrils. These two proteins have very good processing properties. In particular, myosin is more important. When the protein is heated, a disulfide bond can be formed between the myosin molecules and the actin molecule, and a three-dimensional network structure is formed under the action of the molecular hydrophobic group to form a gel. Since the myofibrillar protein is heated to form a gel, this property gives the meat product excellent food use properties such as gel properties, slicing properties, elasticity and water retention. Myosin is a very good substrate for transglutaminase. In the meat protein added with transglutaminase, a catalytic reaction occurs to cause glutamyl residues to react with lysine residues in the gel network. A new joint is formed on the joint to form a stronger bonding force than the disulfide bond, thereby improving the strength and stability of the gel and optimizing the quality of the meat product.
Application in meat products
The nature of the gel formed during the processing of the meat product largely determines the characteristics of the finished product. The added transglutaminase can significantly improve the quality of the gel and improve the elasticity, slicing and yield of the meat. Therefore, transglutaminase is widely used in the processing of various meat products. The application of transglutaminase in meat production includes the following aspects.
Optimize product texture and improve meat quality The texture of meat products is an important feature and a key factor affecting consumer choice. The addition of transglutaminase can significantly improve the quality of meat products. Some researchers have studied the effect of adding transglutaminase on the quality of chicken meatballs, and found that the amount of enzyme added is directly proportional to the hardness of chicken meatballs. At the same time, it was found that the hardness, elasticity and chewiness of the ham sausage were significantly improved by adding 1% transglutaminase to the ham sausage. The transglutaminase is added to the ham, and the sliceability of the ham is improved.
Enhance the water holding capacity of the product and increase the cooking yield. Water retention is an important quality indicator of meat products. It determines the food quality, such as color, aroma, taste, nutrition, juiciness and tenderness of meat products, and affects economic value. Due to the space network structure catalyzed by transglutaminase, it can accommodate a large amount of water, so it can prevent the water product from shrinking during processing and improve the cooking yield of the product. Foreign researchers used peeled chicken breast as raw material to make meat patties, added soy protein and transglutaminase. The results showed that the amount of transglutaminase was proportional to the cooking yield, which was mainly due to transglutamate. The amidase improves the thermal stability of the gel network structure in the meat product, and the structure is stable during the heat treatment, and the yield is improved.
Recombination of minced meat During the processing of meat products, minced meat and meat residue are often produced. How to recombine these low-value meats and improve their application value and economic value is a key issue that all meat factories urgently need to solve. Glutamine transaminase can form intramolecular and intermolecular crosslinks of proteins and is therefore widely used in the reconstitution of meat products. Transglutaminase catalyzes the intramolecular and intermolecular cross-linking of proteins to form novel proteins. In general, the molecular chains are not easily broken under non-enzymatic conditions. Therefore, the meat processed by the enzyme is processed by freezing, thawing, cooking, etc. The method also does not crack, and the use of transglutaminase can recombine the minced meat into a whole large piece of meat, which greatly improves the utilization rate of the raw materials.
The development of healthy and nutritious meat products salt and phosphate plays an important role in the structure of meat products. It is a necessary food additive in the processing of meat products. Long-term intake of excessive salt is harmful to human body. The development of meat products with low salt and healthy nutrition is in recent years. A hot spot in the research of meat products, transglutaminase is a powerful tool for the development of such products. In the process of meat production, transglutaminase can reduce the amount of food additives and maintain the original meat flavor. For example, if the amount of salt in the sausage is reduced to 0.5%, and then 0.25% of glutamine transaminase is added, the sensory quality of the sausage is not much different from that of the sausage with 1.8% salt, indicating that transglutaminase can greatly enhance its condensation. Glue strength; at the same time, only 0.3% phosphate was added to the sausage. Compared with the non-phosphate added only transglutaminase, the texture of the sausage was not obvious.
Studies by Japanese researchers have shown that proteins formed by the use of transglutaminase can be used as a fat substitute. By modifying the gelatin by transglutaminase, it can replace a certain proportion of pig fat and ham, and make hamburger. It is found that there is no significant difference in color and flavor compared with 100% pig fat product, and the fat content It is 2% lower than the former and belongs to low-fat foods. Novozymes uses casein sodium as a raw material, and through the modification of transglutaminase, the fat substitute produced can replace half of the fat in the salami, and the original taste of the product remains unchanged.
Broaden the source of raw meat Beef, mutton and poultry are rich in nutrients, low in fat and high in protein. In the meat consumption structure, it has risen to 35%. The research and development of high-quality meat products such as cattle, sheep and poultry is an urgent problem to be solved in the meat product market in the future. However, due to the defects of raw meat itself, the development of such products is limited. For example, chicken is used as raw material to produce sausage, and the hardness of the product is not high. However, using chicken as a raw material, it was found that the hardness and elasticity of the sausage were remarkably improved by adding transglutaminase.
PSE meat occurs during the slaughtering of pork, turkey and beef. This type of meat is greatly restricted in production due to its white color, poor organization and poor water holding capacity. American Andy et al. have patented the use of transglutaminase to improve PSE meat for the production of meat products. Experiments have shown that the processed chicken and pork processed by this method have good quality and acceptability.
The blood in the muscle tissue is a natural nutrient substance, but since the chemical components in the blood are unstable and easily oxidized, affecting the quality of the product, the blood is rarely used in meat processing. Glutamine transaminase can be combined with hemoglobin and re-added to meat products by modification, which not only improves the color of meat products, retains the nutrients in the meat, but also improves product stability and shelf life.
In summary, glutamine transaminase has been intensively studied as an excellent protein cross-linking agent in the processing of meat products. With the increasing health awareness of consumers, the application of glutamine transaminase in future meat products focuses on two aspects: First, adding a small amount of glutamine transaminase to improve the quality and added value of meat products. In order to increase economic benefits; the second is to use TG enzyme to develop new meat products with low salt, low fat and high nutritional value.
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