1. The effect of pre-slaughter factors on muscle tenderness 1) Type, variety, gender Some studies have found that 30% of the effects on meat tenderness are affected by genetic factors, and the chemical composition of meat is also very different. Generally speaking, the larger the physical condition of the livestock, the thicker the muscle fibers and the older the meat. Under the same conditions, the muscles of the common males are rough and the meat is older. 2) Age In general, the meat of young livestock is tenderer than that of older animals, while the former has a higher content of connective tissue than the latter. The reason for this is that the collagen of young animal bones has a low degree of cross-linking and is easy to be heated and dissolved. The collagen of adult animals is highly cross-linked and is not easily affected by heat, acid and alkali. 3) Muscle parts The tenderness values ​​of the different meats in the muscles are also different. The muscle fiber content and connective tissue content of different parts of the same age group are also different, so the meat tenderness is not the same. The length of the sarcomere of the stiff muscles after slaughter is positively correlated with the tenderness of the meat, which is why the tenderness of the muscles is different. 2. The effect of post-mortem factors on muscle tenderness 1) Temperature The degree of muscle contraction has a great relationship with temperature. Generally speaking, above 15 °C, it is positively correlated with temperature. The higher the temperature, the more intense the muscle contraction. Below 15 °C, the degree of muscle contraction is negatively correlated with temperature. That is to say, the lower the temperature, the greater the degree of shrinkage, and the so-called cold shrinkage is formed under low temperature conditions, and it is determined that the degree of contraction of the muscle at 2 ° C is as large as 40 ° C. 2) Mature After the meat is stiff, it enters the maturity stage. This is not the usual cooking and heating, but a series of biochemical reactions in which the meat naturally occurs at temperatures above freezing, causing the meat to become soft and flavorful. 3) cooking heating During cooking and heating, as the temperature increases, the protein denatures, and the properties of the denatured protein determine the texture of the meat. Method of tenderizing pork The important factors determining the tenderness of meat are mainly three kinds of proteins, namely, actin and myosin in muscle fiber cells; sarcoplasmic protein and sarcoplasmic hard protein in sarcoplasm; collagen and elastin in connective tissue and Meaty protein. The distribution of these three types of proteins is different, and the tenderness of the meat is different. In the processing of meat products, mechanical, physical, and chemical methods are usually used to change the structure of these proteins to cause denaturation, solidification, hydrolysis, and breakage to achieve the purpose of tenderization. At present, there are mainly physical tenderization, chemical tenderization, and biological tenderization. 1. Physical tenderization 1) Natural (low temperature) curing method The slaughtered fresh meat is sent to a cooling chamber with a low temperature, a relative humidity of 85% or more, and a temperature of 10 ° C for a period of time to perform automatic acid removal, which naturally completes the rigidity, unwinding and ripening process of the meat. Since low temperature is not conducive to the growth of microorganisms, it is generally required to be placed under low temperature conditions. 2) Mechanical tenderization Using the action of mechanical force to tenderize the meat, the body is pressed by many sharp blades or sharp needles on the machine, so that the muscle fiber cells and the connective tissue between the muscle fibers are cut and broken, the normal structure of the meat is destroyed, and the performance of the muscle tissue is changed. It increases the surface area of ​​the meat, makes the meat more adhesive, and improves the water holding capacity of the meat, thereby achieving the purpose of tenderization. This method can utilize the meat with poor tenderness and is suitable for various meats, which is more time-consuming and energy-consuming, but can increase the tenderness of meat by 20-50%. 3) Ultrasonic tenderization Ultrasonic tenderized meat is currently less studied. It is generally believed that its cavitation effect, thermal effect and mechanical action are the three theoretical basis for the application of ultrasonic technology. The high-frequency oscillation signal emitted by the ultrasonic generator is transmitted to the medium by the transducer to be converted into a high-frequency mechanical oscillation, and the liquid flows to generate tens of thousands of tiny bubbles, which are negatively propagated in the longitudinal direction of the ultrasonic wave. The zone forms and grows, and it closes rapidly in the positive pressure zone. In this process called “cavitationâ€, the bubble closure can form an instantaneous high pressure of more than 1000 atmospheres, and the continuous high pressure is like a series of small “ The explosion "continuous impact on the object, causing mechanical damage, under the impact of this huge pressure, the muscle fiber breaks and the lysosome ruptures. 4) Ultra high pressure tenderization Since 1973, many studies have shown that high pressure is conducive to improving the tenderness of meat, but little is known about its tenderization mechanism. Some people claim that high pressure treatment increases the inter-molecular spacing and exposes the polar regions, which improves the water retention of the meat and increases the tenderness. 5) Electrical stimulation tenderization Electrical stimulation can be used to improve the tenderness of the meat. This technology is a technique for energizing the carcass at a suitable voltage and current for a suitable period of time. The energy that causes muscle contraction is exhausted from the muscles, and the muscle fibers are relaxed and feel tender. Studies have shown that 550 ~ 700V, 5A current stimulation is the best treatment, and need to stimulate 17 times, each time 60-180s can exhaust all the energy that causes contraction from the muscle. The electric stimulation of the flesh, due to the action of electric current, accelerates the rapid degradation of adenosine triphosphate in the muscle and the decomposition of glycogen to produce various organic acids, so that the pH of the meat is quickly lowered to 6.0, and then the muscles are cold-processed. Prevents the cold contraction of the meat, thereby increasing its tenderness. At the same time, due to the degradation of adenosine triphosphate in the meat, the decomposition of the glycogen produces various flavor substances, which can further improve the meat quality and appearance color. Electrical stimulation has several major advantages. (1) Improve the "generation" of the marble pattern of the body so that the meat can be graded earlier after slaughter. (2) Electrical stimulation causes the muscle to secrete autolytic enzyme in advance, which increases the tenderness of the meat and enhances "maturing" when the meat is cooled and stored. (3) Make the color of the muscles brighter and taste more palatable. (4) Increase the shelf life of retail meat. 2. Chemical tenderization 1) Polyphosphate Tenderization Polyphosphates include pyrophosphoric acid, metaphosphoric acid, and tripolyphosphate. It was used in meat processing in 1950. The tenderization method is to mix the polyphosphate into a marinade for pickling or injecting into the meat, followed by rolling. The general addition amount is 0.125%~0.375%, not more than 0.5%. Its mechanism of action: increase the pH value of the meat, blend metal ions, increase the electrostatic repulsion of the protein, increase the solubility of myosin, dissociate the actomyosin, and increase the amount of salt-soluble protein. 2) Calcium salt injection tenderization Tests have shown that poultry meat with strong muscle toughness and poor tenderness is injected into the chicken breast muscle immediately after slaughter with a concentration of 0.15 mol of calcium chloride solution. After 12 h, the shear force value is higher than the control value (injection equivalent KC1). Significantly reduced, tenderness has been significantly improved, providing a new way for meat tenderization. The mechanism is: high concentration of Ca osmotic muscle cells, activation of CANP enzyme and alkaline phosphatase, promote glycolysis, accelerate lysosomal rupture, tissue protein release, and jointly promote the improvement of tenderness. 3) Hydrochloric acid cysteine ​​tenderization Cysteine ​​hydrochloride can make the active group of the enzyme molecule SH, change the structure, activate the system of the cystease, release the active protein, hydrolyze the peptide structure of the polymerized collagen, and partially hydrolyze the elastic protein in the connective tissue. 4) Carbonate tenderization The carbonate used includes sodium carbonate and sodium hydrogencarbonate. The tenderization method is to prepare the carbonate into a liquid (1% to 2%), and some raw materials such as crude and old hard animal materials are immersed therein. The carbonate solution is generally alkaline. It has a certain corrosive effect on the protein, can destroy the structure of the meat, promote the structure to change, and increase the tenderness to a certain extent, but at the same time has a certain loss of nutrition. 3. Biological tenderization 1) Enzymatic tenderization There are two main sources of enzymes for meat tenderization, plant extraction and microbial culture. The enzymes extracted from plants mainly include papain, bromelain, ficin and ginger protease. These enzymes have a strong decomposition effect on connective tissue. After use, the degradation rate of hydroxyproline which is closely related to meat tenderness can reach 11.4%~43.0%, and the tenderization effect is very remarkable. Among them, papain and pineapple Proteases are the main class of commercial enzymes. Secondly, ginger protease has attracted the attention of researchers at home and abroad at a low cost. There are many types of enzymes extracted from cultures of certain bacteria and fungi, such as protease 15, subtilisin, Rhozgme, pronase and hydrolyzed protease D. Most of these enzymes mainly have the properties of decomposing muscle fiber membranes and myofibrillar proteins, some of which are more specific. Their isolated and isolated strains secrete elastase, which has a strong ability to decompose connective tissue between tendons and muscle fibers, while the decomposition of other proteins is relatively weak. 2) hormone tenderization This method mainly injects hormonal preparations such as insulin and adrenaline before the slaughter of livestock, accelerates the metabolism of sugar, decomposes the sugar, releases it from the urine when it is discharged from the urine or slaughter, so that the acid produced during the stagnation process is less, the pH of the meat. The value is as high as 6.2 or more, which suppresses the dead body and improves the tenderness. However, the flesh is dark, and it is called "cutting blackening." to sum up Tenderness is one of the most important eating qualities of livestock muscles. The self-maturation and external treatment of post-mortem meat is a key factor in improving the quality of meat. Factors affecting tenderness after slaughter include temperature, pH, solubility and cross-linking of collagen, and activity of calcium-activating enzyme. The methods of exogenous treatment tenderization for these factors can be divided into three types: physical tenderization (electric stimulation, hanging, etc.), chemical tenderization (salt, organic acid, etc.) and biological tenderization methods. the same. Some processes are mature and widely used, and some are still in the research stage. These techniques are used alone or in combination at the time of production, but the combined effect of using these techniques in actual production is not equal to the sum of the effects obtained by using these technologies alone. To understand the factors affecting the tenderness of meat after slaughter and the tenderization mechanism, it is expected to improve the quality of the cooled meat, provide high-quality raw meat for deep processing, and promote the development of the meat processing industry. Stretcher Cart,Hydraulic Stretcher,Hydraulic Cart Care Home Healthcare Supplies Co., Ltd. , http://www.szmedicalmattress.com