The hottest meat preservation technology

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Meat preservation and preservation technology (Part I)

meat preservation and preservation has been an important topic of human research since ancient times. With the change of modern people's lifestyle and rhythm, the traditional meat preservation technology can no longer meet people's needs, and it is imperative to further study the meat preservation and preservation technology. Scholars at home and abroad have conducted extensive research on the preservation of meat. At present, it is believed that any kind of fresh-keeping measures have shortcomings, and comprehensive fresh-keeping technology must be adopted to give full play to the advantages of various preservation methods to achieve the purpose of complementary advantages and multiplying effects; ⑴ microbial pollution, growth and reproduction; ⑵ fat oxidation; ⑶ gas discoloration of myoglobin. These three factors interact. The reproduction of microorganisms will promote the oxidation of oil and the discoloration of myoglobin, and the oxidation of oil will also change the microbial flora and promote the discoloration of myoglobin. The author summarizes the current methods of meat preservation

1traditional meat preservation techniques

1.1 low temperature cold storage

low temperature preservation is a commonly used technical measure. In view of the national conditions of our country, Cold chain system is the most important means of meat preservation. Cold storage means that meat is kept at a temperature slightly higher than its freezing point, usually between 2~4 ℃. Within this range, most pathogenic bacteria stop breeding, and then psychrophilic spoilage bacteria can still grow. Recently, it was found that Listeria monocytogenes and Yersinia enterocolitica can also reproduce. The growth rate of bacteria in meat is quite fast. Under suitable conditions, some bacteria only reproduce for 20min or less. In fact, generally, such a fast rate cannot be achieved, because it is impossible to meet all environmental conditions at the same time. The length of bacterial growth period depends on species, nutrients, temperature, pH value and water activity, Low temperature preservation has the disadvantages of measuring the stress change on the sample: (1) the quality of meat will decline due to the formation of ice crystals and salting out effect during freezing and thawing; (2) If the package is poor, the surface moisture will sublimate and cause "freeze burn" phenomenon; (3) The transportation cost is high during freezing. "

1.2 low water activity preservation

water activity is not the total water content in food, but refers to the water available to microorganisms. The reproduction speed of microorganisms and the composition of microbiota depend on water activity (AW) 。 Most bacteria can only reproduce in the matrix with aw higher than 0.85. The water activity requirements of Botox are 0.94~0.96, Salmonella is 0.92, general bacteria is 0.90, and Staphylococcus aureus is 0 88 when the water activity is reduced to about 0.7, most microorganisms are inhibited. According to the relss report, 45 kinds of Penicillium can be isolated from the interior and surface of meat products. Only Aspergillus can grow at low water activity and high temperature. The most common low water activity preservation methods are drying and adding salt and sugar. Other additives such as phosphate and starch can reduce the water activity of meat

1.3 heating treatment

heating treatment is a fresh-keeping technology used to kill spoilage bacteria and pathogens in meat products and inhibit the enzyme activity that can cause spoilage. Although heating treatment can inhibit bacteria and enzymes, heating can not prevent the oxidation of oil and myoglobin, but can promote it. Therefore, heat-treated meat products must be used in conjunction with other preservation methods

1.4 fermentation treatment

fermented meat products have good preservation characteristics. It uses artificial environment control, uses the growth of lactic acid bacteria in meat products to dominate, converts carbohydrates in meat products into lactic acid, reduces the pH value of products, and inhibits the growth of other microorganisms. Fermented meat products also need to be combined with other preservation technologies

2 modern preservative and fresh-keeping technologies

although many traditional meat preservation technologies are still in use, new preservative and fresh-keeping technologies have developed rapidly. Modern meat preservative and fresh-keeping technologies include joint preservatives, vacuum packaging, controlled atmosphere preservation technology and radiation preservation technology

testing the crack growth rate of metal materials and the threshold value of materials 2.1 preservatives and preservatives

food additives related to preservation in meat products are divided into four categories, which are widely used in auto parts enterprises, scientific research institutions, spring manufacturers and other industries: 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 mainly include various organic acids and their salts. Organic acids used in meat preservation include acetic acid, formic acid, citric acid, lactic acid and its sodium salt, anti cyclic acid, sorbic acid and its potassium salt, phosphate, etc. Many experiments have proved that the use of these acids alone or in combination has a certain effect on prolonging the storage life of meat, among which acetic acid, sorbic acid and its salts, sodium lactate are the most used. (1) Acetic acid starts from 1.5%. 2.2 when there are loose parts and components in the operation of the experimental machine, it has obvious antibacterial effect. Within the range of 3%, acetic acid will not affect the color of meat,. Because at this concentration, due to the antibacterial effect of acetic acid, the growth of microorganisms is slowed down, and the black and green meat color caused by mold spots is avoided. When the concentration exceeds 3%, it has an adverse effect on the meat color, which is caused by the acid itself. Foreign studies have shown that soaking fresh meat with a mixture of 0.6% acetic acid and 0.046% formic acid for 10s, not only the number of bacteria is greatly reduced, but also its flavor can be maintained, with little impact on the color. For example, using 3% acetic acid alone, It can inhibit bacteria, but has adverse effects on color. When it is treated with 3% acetic acid +3 ascorbic acid. Due to the color protection effect of ascorbic acid, the meat color can be maintained very well. Anderson (1983) sprayed the carcass with 40 ℃ hot water first, and then treated with 3% acetic acid, the bacterial content could be reduced by 96.8%. Drtaoed (1983) sprayed the carcass with an aqueous solution of 2% acetic acid +1% lactic acid +0.25% citric acid +0.1% ascorbic acid, which can significantly prolong the shelf life (2) the use of sodium lactate is still limited. USDA believes that sodium lactate is safe, and the maximum dosage is as high as 4%. There are two mechanisms of sodium lactate antisepsis. The addition of sodium lactate can reduce the water activity of the product, thus preventing the growth of microorganisms; Lactate ion has antibacterial function. Sodium lactate has inhibitory effects on rats, Salmonella and Staphylococcus aureus. At present, sodium lactate is mainly used for internal antisepsis, (3) potassium sorbate is widely used in meat products. Its antibacterial effect lies in that it can combine with the sulfur group in the microbial enzyme system, thus destroying many important enzyme seconds, so as to achieve the purpose of inhibiting microbial proliferation and antisepsis. Potassium sorbate can act alone in fresh meat preservation, It can also combine with phosphate and acetic acid. (4) Phosphate, as a quality improver, plays its role in corrosion prevention and preservation. Phosphate has the following functions in the same products: significantly improving the water retention of meat products; Using its additive to delay the oxidative rancidity of products and enhance the antibacterial effect of preservatives, phosphate has become an indispensable additive in the meat industry since the United States Department of agriculture stipulated that 0.5% phosphate can be added to meat products in 1982

(to be continued)

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