The main application of modified atmosphere fresh-

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The main application of modified atmosphere packaging technology

modified atmosphere packaging (modifiedatmospherepackaging), also known as displaced gas packaging, referred to as map, can be defined as "the technology of regulating the gas environment of food in materials that can prevent gas from entering and leaving". An important feature of map is to regulate the gas composition in the package at the beginning of storage, so as to inhibit the decay and deterioration of food, maintain the quality of perishable food in the normal shelf life or extend its shelf life. Therefore, modified atmosphere packaging is also known as activeatmospherepackaging. Modified atmosphere packaging is mainly used for food preservation

the packaging principle of modified atmosphere packaging is to use modified atmosphere fresh-keeping gas (2 ~ 4 gases are mixed according to the characteristics of food), replace the air in the packaging box or packaging bag, change the external environment of the food in the box (bag), inhibit the growth and reproduction of bacteria (microorganisms), slow down the metabolism of new fresh fruits and vegetables, and thus extend the fresh-keeping period or shelf life of food. The modified atmosphere fresh-keeping gas is generally composed of carbon dioxide (CO2), nitrogen (N2), oxygen (O2) and a small amount of special gases (NO2, SO2, AR, etc.). The functions of various gases are as follows: CO2 gas can inhibit the growth and reproduction of most spoilage bacteria and molds, and is the main bacteriostatic agent in fresh-keeping gases; O2 can inhibit the growth and reproduction of most anaerobic spoilage bacteria, maintain the color of fresh meat, and maintain the respiratory metabolism of fresh fruits and vegetables; N2 is an inert gas, which generally has no chemical reaction with food and is not absorbed by food. It is used as a filling gas in modified atmosphere packaging to prevent the packaging from collapsing due to the escape of CO2 and other gases from the packaging. For different foods, fruits and vegetables, the composition and proportion of fresh-keeping gas are also different. The key to the modified atmosphere packaging of crops is to keep the oxygen permeability of packaging materials consistent with the respiratory rate of products

the application of modified atmosphere packaging in some products has been relatively mature, and has been widely used in the preservation of fruits and vegetables and clean vegetables. In addition, modified atmosphere preservation technology is also applied to the packaging of cold fresh meat and aquatic products

fresh fruits and vegetables after picking still have life activity during storage. The substances and heat released by respiration and transpiration have a great impact on the quality of fruits and vegetables, resulting in weight reduction, nutrition loss, appearance and color damage, and finally lead to their decay and deterioration, losing their edible value. On the basis of cold storage, modified atmosphere packaging of fruits and vegetables is to inhibit the respiration of fruits and vegetables and reduce their water evaporation rate by regulating and controlling the environmental temperature, humidity, gas concentration and other factors in the packaging, so as to achieve the purpose of extending their shelf life. The modified atmosphere packaging gas of fruits and vegetables is composed of O2, CO2 and N2. The fruits and vegetables are packed with breathable film, filled with low O2 and high CO2 and sealed after replacement with mixed gas, so that the O2 content in the package is lower than the air and the accumulated CO2 is higher than the air. The gas exchange is carried out through the film, so as to achieve the modified atmosphere balance conducive to the fresh environment of fruits and vegetables and maintain weak aerobic respiration. Most fruits and vegetables are packed in a mixed proportion of 5%o2, 5%co2 and 90%n2, and have a long fresh-keeping period at a low temperature of 6 ℃ -8 ℃

modified atmosphere packaging is also suitable for fresh-keeping of clean vegetables. Clean vegetables, also known as cut fruits and vegetables and semi processed fruits and vegetables, are new food processing products for office workers. They are safe, fresh, nutritious and convenient, but they are prone to browning after cutting. Using modified atmosphere packaging to reduce oxygen content can maximize the shelf life. For example, cut lettuce in the United States prevents browning with 1%-3% O2, 5%-6% CO2 and 90%n2. Modified atmosphere fresh-keeping packaging is also suitable for the fresh-keeping of peeled and sliced apples, potatoes, leafy vegetables and other fruits and vegetables. Developing the packaging film suitable for the fresh-keeping effect of modified atmosphere packaging of fruits and vegetables is the key to broaden the way of fresh-keeping of fruits and vegetables

with the improvement of people's living standards, the demand for cold fresh meat is also increasing, but because the fresh-keeping period of cold fresh meat is very short, it is difficult to maintain its color. If we want to produce and distribute cold fresh meat on a large scale, the key is to solve the problem of preservation. Nowadays, the thinner the recycled materials are, the more complex modified atmosphere fresh-keeping packaging is generally used internationally to solve such problems

the packaging of cold fresh meat mainly includes vacuum packaging, nitrogen filled packaging and composite modified atmosphere fresh-keeping packaging. Because the color of the cold fresh meat in vacuum packaging and nitrogen filled packaging is dark after packaging, and the original fresh color of the fresh meat is lost, the composite modified atmosphere fresh-keeping packaging is generally used. The fresh-keeping period of the cold fresh meat after the composite modified atmosphere fresh-keeping packaging is days, and the color and flavor of the fresh meat can be maintained. The mixed fresh-keeping gas in the modified atmosphere fresh-keeping package of cold fresh meat is composed of oxygen and carbon dioxide. Among them, the concentration of oxygen is relatively high, which can make the chilled meat keep the bright red luster of fresh meat; However, an appropriate concentration of carbon dioxide can inhibit the growth and reproduction of bacteria and microorganisms. After the modified atmosphere packaging is filled with an appropriate proportion of fresh-keeping gas, it can not only ensure the quality of fresh meat unchanged, but also maintain its original fresh color and attract consumers to buy

after adopting the modified atmosphere fresh-keeping packaging technology, it is not only conducive to extending the fresh-keeping period of cold fresh meat, maintaining the appearance and color of cold fresh meat, leading to the bankruptcy of South Africa highveld, resulting in the supply of vanadium free slag, so as to improve the quality, safety and hygiene of cold fresh meat, but also conducive to reducing the number of enterprise distribution, saving production costs, expanding the scope of marketing, and promoting the improvement of enterprise image

the deterioration of fresh aquatic products and marine fish mainly includes bacteria that decompose trimethylamine oxide in fish meat to release trimethylamine with putrefaction taste, oxidative rancidity of fish fat, degradation of fish meat by enzymes in fish body, softening of fish meat, and toxic toxins produced by bacteria on the surface of fish body (aerobic Escherichia coli, anaerobic traditional plastics need more than 100 years for natural degradation in the natural world), which endanger human health. The gas used for modified atmosphere packaging of fish is composed of CO2, O2 and N2, of which the concentration of CO2 is higher than 50%, which inhibits the growth of aerobic bacteria and mold without making fish exude; O2 concentration of 10%-15% inhibits the propagation of anaerobic bacteria. The gills and viscera of fish contain a large number of bacteria, which need to be removed, cleaned and treated with disinfectant before packaging. Because CO2 is easy to seep out of plastic film, the packaging material of modified atmosphere packaging for fish needs composite plastic film with high gas barrier, which can be kept for days at the temperature of 0 ℃ -4 ℃. British tuna is packaged with 35%-45% CO2/55%-65%n2 gas, with a shelf life of 6 days

since the 1930s, fresh beef and mutton have been stored and transported in large packaging bags abroad, but the large-scale commercial application of this technology began after 1970. In 1979, British Mark & Spencer company launched map meat products, which were applied to fish, ham and other aspects two years later. Foreign countries began to study the modified atmosphere preservation of fruits and vegetables in 1955. Marceland of the Plant Physiology Laboratory of Gerhard National Research Center in the United States began to study the storage of apples and pears with various PE films, and systematically studied the changes of oxygen and carbon dioxide in the storage environment. In 1960, he published a research report, which was called physiological packaging storage. The formula, thickness and specification of fresh-keeping film are determined according to the biological modulus of fruit respiration. Under specific temperature conditions, the gas composition in the bag is maintained with the help of the dual effect of PE film through O2 and CO2

modified atmosphere packaging in China began in the 1990s. The national agricultural products preservation engineering technology center developed 24 formulas of PVC fresh-keeping film for fruits and vegetables in 1988, from which 32 varieties and 47 specifications were selected for the practical application of fresh-keeping film bags such as cucumbers, celery, grapes, apples and Yali pears. In recent years, modified atmosphere packaging technology has become a research hotspot. Modified atmosphere packaging for fruits and vegetables, which is not only safe, effective, but also simple to operate, has become the focus of research at home and abroad in recent years, and is widely used

with the development of modified atmosphere packaging technology, it is modified atmosphere packaging equipment. High efficiency modified atmosphere packaging production equipment the main equipment of food modified atmosphere packaging production is vacuum modified atmosphere packaging machine and gas proportioner. At present, China's packaging production enterprises have been able to provide all kinds of bag or box packaging machines, full-automatic vacuum modified atmosphere packaging machines and gas proportioners for food enterprises. For example, Shanghai JUGANG Machinery Manufacturing Co., Ltd., through technical cooperation with the school of mechanical engineering and automation of Shanghai University and the school of food science and technology of Shanghai Fisheries University, developed a series of modified atmosphere packaging machines and gas proportioners with bag and box packaging based on the production of vacuum inflatable packaging machinery series products. The developed products include box packaging zqt-1

d400 and map-200 full-automatic modified atmosphere packaging machines adopt programmable logic controller (PLC) and built-in gas mass flow proportioner. Various packaging parameters such as gas mixing ratio, gas replacement time, heat sealing temperature and time, film sealing traction and mold movement time control can be automatically controlled through LCD touch setting, which is easy to operate

recently, the United States has further strengthened the research on the new generation of modified atmosphere fresh-keeping food packaging system. The delta3000ld (longdwell) assembly line packaging machine for high-speed modified atmosphere packaging newly developed by ilapak company can pre program up to 64 production schemes to ensure rapid and simple adjustment of packaging size. Its features also lie in the precise control of inflation, the long-term maintenance of the high-density sealing port, and the quality control device that does not put on the packaging bag when there is no product

at the same time, Multivac has developed a new tray sealing machine for poultry and packaged ready to eat meat products. This new technology encapsulates the product in a shallow tray after air conditioning, which is more to evaluate the reliability of the material itself under long-term use conditions. While ensuring complete sealing, the product can obtain better visual effects. Rovema packaging machinery company's series of modified atmosphere flexible packaging bags and pillow packaging are suitable for coffee, breakfast cereals, baked goods and other products. Its vertical forming/filling/vacuum pumping/inflation/sealing system can handle liquid, viscous, granular or solid products; The speed of pillow type packaging machine can reach 180 packages/min at the fastest, and it can be produced from single package to a large number of food packages

as a kind of intelligent packaging technology, the application of modified atmosphere packaging technology in countries around the world has just begun, and some technologies are still in the stage of experiment and research. It can be said that this technology is also in its infancy. How to seize this opportunity, develop China's packaging industry, improve the technical content of China's packaging, in order to meet the requirements of the international economic form under the new form, is a problem faced by every packaging person. With the changes of the times, the variety of goods is more diverse and complex, and the functions of packaging are also more and more. The wave of high and new technology has pushed packaging to a higher level of development. Modified atmosphere packaging technology will surely occupy a place in the era of intelligent packaging

source: Food Forum

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