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The preservation and preservation of meat has been an important subject for human research since ancient times. With the change of lifestyle and rhythm of modern people, traditional meat preservation technology can no longer meet people's needs. Therefore, it is imperative to thoroughly study the preservation and preservation technologies of meat. Row. Domestic and foreign scholars have extensively studied the preservation of meat. At present, it is considered that any kind of preservation measures have their shortcomings, and comprehensive preservation techniques must be used to give full play to the advantages of various preservation methods to achieve the purpose of complementing each other and multiplying the effects. The corruption of meat is mainly caused by three factors: (1) microbial contamination, growth and reproduction; (2) fat oxidation failure; (3) myoglobin gas discoloration. The interaction of these three factors, microbial reproduction will promote the oxidation of lipids and myoglobin discoloration, and oxidation of lipids will also change the microbial flora and promote the discoloration of myoglobin, the author reviewed the current methods of preservation of meat preservation. 1 Traditional Meat Preservation Technology 1.1 Low-temperature cold storage and fresh-keeping are the commonly used technical measures. In view of China's national conditions, the cold chain system is the most important means for preservation of meat. Refrigerated meat is kept at a temperature slightly above its freezing point, usually between 2 and 4°C. In this range, most pathogenic bacteria stop breeding, and chills and spoilage bacteria can still grow. Proliferative bacteria and Y. enterocolitica can also be propagated. The growth rate of bacteria in meat is quite fast. Under appropriate conditions, some bacteria reproduce only for 20 minutes or less. In fact, under normal circumstances, such a fast rate cannot be achieved because all the environmental conditions are met simultaneously. Impossible, bacterial growth period depends on the species, nutrient composition and temperature, PH value and water activity, the following disadvantages of low temperature preservation: (1) freezing and thawing process will be due to the formation of ice crystals and salting effect, so that The quality of meat is declining; (2) If the packaging is poor, the surface moisture will sublimate and cause "freeze-burning" phenomenon; (3) The transportation cost is high when the frozen quail. 1.2 Low moisture activity Fresh water activity is not the total moisture content of the food, but the moisture that the microorganism can use. The rate of propagation of microorganisms and the type of microbiota composition depend on the water activity (AW). Most bacteria can only be propagated in substrates with an AW higher than 0.85. Botox water activity requirements are 0.94 to 0.96, Salmonella is 0.92, bacteria are generally 0.90, and Staphylococcus aureus is 0.87-0.88. When water activity is reduced to 0.7 When left and right, most of the microorganisms were inhibited by RELSS. 45 penicillins could be isolated inside or on the surface of the meat product. Only the Aspergillus could grow at low water activity and high temperature. The most common low moisture Active preservation methods include drying and adding salt and sugar. Other additives such as phosphate, starch, etc. can reduce the water activity of meat. 1.3 Heat treatment Heat treatment is a fresh-keeping technique for killing spoilage bacteria and pathogenic bacteria present in meat, and inhibiting enzyme activity that can cause spoilage. Although heat treatment can play a role in inhibiting bacteria and inactivating enzymes, heating cannot be performed. To prevent the oxidation of lipids and myoglobin, but to promote the role, so heat treated meat products must be used in conjunction with other preservation methods. 1.4 Fermentation Processing Fermentation of meat products has better preservation characteristics. It is controlled by artificial environment. The growth of lactic acid bacteria in meat products is dominant, and the carbohydrates in meat products are converted into lactic acid, and the PH value of products is reduced, while others are inhibited. The growth of microorganisms and the processing of meat products for fermentation must also be combined with other preservation techniques. 2 Modern anti-corrosion and preservation technologies Although many traditional meat preservation technologies are still used today, new anti-corrosion and preservation technologies have developed rapidly. Modern meat anti-corrosion and preservation technologies include joint meeting rot preservatives, vacuum packaging, modified atmosphere preservation technologies and radiation preservation. Four kinds of technology. 2.1 Preservatives and Preservatives Food additives related to preservation in meat products are classified into four categories: preservatives, antioxidants, colorants and quality improvers. Preservatives are divided into chemical preservatives and natural preservatives. Preservatives are often used in combination with other preservation techniques. 2.1.1 Chemical preservatives Chemical preservatives are mainly organic acids and their salts. The organic acids used for meat preservation include acetic acid, formic acid, citric acid, lactic acid and its sodium salt, ascorbic acid, sorbic acid and its potassium salt, and phosphates. Many tests have shown that these acids alone or in combination have a certain effect on the prolonged shelf life of meat, of which the most used are acetic acid, sorbic acid and its salts, and sodium lactate. (1) Acetic acid has a significant antibacterial effect from 1.5%. Within 3%, acetic acid does not affect the color of meat. Because at this concentration, due to the bacteriostatic action of acetic acid, the growth of microorganisms is slowed down, and the flesh color caused by mildew spots is prevented from turning black and green. When the concentration exceeds 3%, there is an adverse effect on the flesh color, which is caused by the acid itself. As a result, foreign studies have shown that the use of 0.6% acetic acid plus 0.046% formic acid mixture impregnated with fresh meat 10S, not only the number of bacteria greatly reduced, and can maintain its flavor, almost no effect on color, such as the use of 3% acetic acid alone, Can be antibacterial, but can have good color on the color. ANDERSON (1983) first sprayed the carcasses with hot water at 40°C and then treated with 3% acetic acid, which reduced the bacterial content by 96.8%. DRtAoed (1983) sprayed carcass with an aqueous solution of 2% acetic acid + 1% lactic acid + 0.25% citric acid + 0.1% ascorbic acid, which can significantly extend the shelf life. (2) The use of sodium lactate is still limited. USDA believes that sodium lactate is safe, the maximum amount used up to 4%, there are two mechanisms for the preservation of sodium lactate, the addition of sodium lactate can reduce the water activity of the product, thus preventing the growth of microorganisms; lactate ions have antibacterial functional groups. Sodium lactate harms mice, Salmonella and Staphylococcus aureus. At present, sodium lactate is mainly used for anti-corrosion within the body. (3) Potassium sorbate is widely used in meat products. The antibacterial effect depends on its ability to Sulfur group binding in the microbial enzyme system destroys many important enzyme seconds, so as to inhibit the proliferation and preservation of microorganisms. Potassium sorbate can be used alone in fresh meat preservation and can also be combined with phosphate and acetic acid. (4) Phosphate is used as a quality improver to exert its antiseptic and fresh-keeping effects. Phosphate plays the following role in the same product: it significantly improves the water retention capacity of meat products; it uses its additive action to delay the oxidative rancidity of products, and enhances the antibacterial properties of preservatives. As a result, since the United States Department of Agriculture regulated the addition of 0.5% phosphate to meat products in 1982, phosphate has become an indispensable additive in the meat industry. 2.1.2 Natural Preservatives Natural Preservatives are guaranteed on the one hand and on the other hand are better adapted to the needs of consumers. At present, domestic and foreign research in this area is very active. Natural preservatives are the development of preservatives in the future. trend. (1) Anti-oxidative deterioration properties in tea. Tea polyphenols play a role in the preservation and preservation of meat in three ways; anti-lipid oxidation; antibacterial; deodorant substances. (2) Spice extracts. Many spices contain bactericidal and bacteriostatic ingredients, which are safe and effective as a preservative after extraction. The allicin and alliin in garlic, the nutmeg in nutmeg, the volatile oil in cinnamon, and the clove oil in cloves all have good bactericidal and antibacterial effects. (3) Nisin is a novel technology for the preservation of meat using Nisin. Nisin is a peptide antibiotic synthesized by certain Streptococcus lactis. It can only nail Gram-positive bacteria and has no effect on yeast, mold and Gram-negative bacteria. Nisin is a narrow spectrum antimicrobial agent. Nisin can effectively prevent the effective action of Clostridium botulinum, which is the main microorganism of food spoilage. At present, there are two forms of using Nisin, one is inoculation of live lactic acid bacteria into food; the other is the separation and utilization of its metabolite Nisin. In addition, natural preservatives such as trehalose, mannan, chitosan, and lysozyme are under study. 2.2 vacuum packaging technology vacuum packaging technology is widely used in food preservation, China's use of vacuum packaging of meat products is increasing, the role of vacuum packaging are mainly four aspects: (1) inhibit microbial growth: prevent secondary pollution; (2 ) Slow down the rate of fat oxidation, (3) Make meat clean and improve competitiveness. There are three forms of vacuum packaging. The first is to put the sorted meat into the packaging bag, draw out the air, then vacuum pack, and then blow the hot air. , The shrinkage of the heated material, close to the surface of the meat, the second method is thermoformed rolling packaging, the third method is vacuum shrink packaging, this method is widely used in Europe. 2.3 Modified atmosphere packaging technology Modified atmosphere packaging technology, also known as ventilation packaging, puts food in the sealed standard, draws out air, and replaces the gas environment inside the packaging with a selected gas to inhibit the growth of microorganisms, thereby prolonging the food shelf. period. There are three commonly used gases for modified atmosphere packaging: (1) CO2 inhibits the growth of bacteria and fungi, especially in the early stages of bacterial growth, and also inhibits the activity of enzymes. It has a better antibacterial effect at low temperatures and 25% concentration, and has a water-soluble Sex. (2) Oxygen acts to maintain oxygenated myoglobin, which makes the flesh color brighter and can inhibit anaerobic bacteria, but it also creates a good environment for many harmful bacteria. (3) Nitrogen is an inert filling gas and nitrogen does not affect The color of the meat can prevent oxidative rancidity, mold growth and parasite damage. In the preservation of meat, carbon dioxide and nitrogen are the two main gases. The presence of a certain amount of oxygen is conducive to prolonging the shelf life of meat. Therefore, it is necessary to select the appropriate proportion for mixing. The proportion of gas preserved in the modified atmosphere of European fresh meat is oxygen. : Carbon dioxide: Nitrogen = 70:20:10 or Oxygen: Carbon dioxide = 75:25. At present, the most effective fresh meat preservation technology in the world is the CAP system with high CO2 inflatable packaging. 2.4 Meat radiation preservation technology Research on meat radiation preservation technology has been for more than 40 years. Radiation technology uses the radiant energy of atomic energy rays to sterilize. At present, it is believed that radiation is used to illuminate the safety of food. The Joint Commission on Food Radiation (EDFI) recommends that all major categories of foods be irradiated at a dose of 100 million rads or less. This dose does not cause toxicological hazards. In 1988, China University of Science and Technology and Hefei Second Commercial Bureau jointly researched the “Fresh Lamb Radiant Preservation Technologyâ€. The results were satisfactory. At room temperature, preserved pork at 25°C was similar in color, smell and taste to fresh meat. The formation of radiation products is only a simple decomposition of the normal ingredients in foods, such as protein decomposition into amino acids, lipoxygen decomposition into glycerol and fat, as for special radiation products (URPS), little is known. The effectiveness of radiation preservation technology needs further study. In short, the preservation of meat needs comprehensive application of various anti-corrosion and preservation measures above, exerts their respective advantages and achieves the best preservation effect. The trend of meat preservation and preservation at the end will be the application of natural preservatives, the application of new packaging technologies and the widespread use of irradiation technology.