Main application and trend of modified atmosphere

2022-08-01
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Main applications and trends of modified atmosphere packaging technology

modified atmosphere packaging, also known as displaced gas packaging, or map for short, can be defined as "a technology to regulate 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 packaging during the initial storage, so as to inhibit the decay and deterioration of food, maintain the quality of perishable food within the normal shelf life or extend its shelf life. Therefore, modified atmosphere packaging is also called active atmosphere packaging. 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 kinds of gas are mixed according to the characteristics of food) to replace the air in the packaging box or 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 controlled 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 antibacterial agent in the fresh-keeping gas; 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 packaging collapse due to the escape of CO2 and other gases from the packaging. For different foods, fruits and vegetables, the components and proportions 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, vegetables and clean vegetables. In addition, modified atmosphere preservation technology is also applied to the packaging of cold fresh meat and aquatic products

the picked fresh fruits and vegetables still have life activity during the storage period. 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 of fruits and vegetables, and eventually 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 control the environmental temperature, humidity, gas concentration and other factors in the packaging to inhibit the respiration of fruits and vegetables and reduce their water evaporation rate, so as to achieve the purpose of extending their shelf life. The modified atmosphere packaging gas for 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 controlled atmosphere balance that is 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 preservation period at a low temperature of 6 ℃ -8 ℃

modified atmosphere packaging is also suitable for fresh keeping of clean vegetables. Clean vegetables are also called cut fruits and vegetables and semi processed fruits and vegetables. In order to cater to the emerging food processing products of office workers, they are safe, fresh, nutritious and convenient, but they are easy to browning after cutting. Using modified atmosphere packaging to reduce oxygen content can maximize shelf life. For example, cut lettuce in the United States can prevent browning with 1%-3% O2, 5%-6% CO2 and 90%n2. The modified atmosphere fresh-keeping package is also suitable for the fresh-keeping of peeled and sliced apples, potatoes, leafy vegetables and other fruits and vegetables. It is the key to broaden the fresh-keeping ways of fruits and vegetables to develop the packaging film suitable for the fresh-keeping effect of modified atmosphere packaging of fruits and vegetables

with the improvement of people's living standards, there is an increasing demand for cold fresh meat. However, due to the short preservation period of cold fresh meat, 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 modified atmosphere packaging is generally used in the world to solve the problem of impacting the sample

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 compound modified atmosphere fresh-keeping packaging is generally used. The fresh-keeping period of the cold fresh meat after the compound 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 packaging of cold fresh meat is composed of oxygen and carbon dioxide. The higher concentration of oxygen can make the chilled meat keep the bright red color of fresh meat; The 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 that the quality of the fresh meat fixed on the injection mold by the flange remains 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 the cold fresh meat, maintaining the appearance color of the cold fresh meat, thus improving the quality, safety and hygiene of the cold fresh meat, but also conducive to reducing the distribution times of the enterprise, saving production costs, expanding the marketing range, and promoting the improvement of the enterprise image

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

since the 1930s, foreign countries have begun to pack fresh beef and mutton in large packaging bags for fresh storage and transportation, 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 is 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 by virtue of the dual effect of PE film through O2 and CO2

modified atmosphere packaging in China began in the 1990s. In 1988, the national agricultural products preservation engineering technology center developed 24 formulations of PVC fresh-keeping films for fruits and vegetables, from which 32 varieties and 47 specifications were selected for the practical application of fresh-keeping film bags such as cucumber, celery, grape, apple and Yali Pear in the deteriorating air quality of cities in China. In recent years, modified atmosphere packaging technology has become a research hotspot. Modified atmosphere packaging for fruits and vegetables is not only safe, effective, but also simple to operate. It has become the focus of research at home and abroad in recent years, and has been widely used

with the development of modified atmosphere packaging technology is the modified atmosphere packaging equipment. High efficiency modified atmosphere packaging production equipment the main equipment for the production of food modified atmosphere packaging is vacuum modified atmosphere packaging machine and gas proportioner. At present, China's packaging manufacturers have been able to provide various 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, has 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 have 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 new high-speed modified atmosphere packaging delta 3000 LD (long dwell) assembly line packaging machine developed by ilapak company can pre program up to 64 production schemes to ensure rapid and simple adjustment of packaging size. It also features a quality control device that can precisely control the inflation, the high-density sealing port can be maintained for a long time, and the packaging bag can not be used 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. The new technology encapsulates the product in a shallow tray after air conditioning. While ensuring complete sealing, the product can obtain better visual effect. 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 most, 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 the world has just begun, and some technologies are still in the stage of experiment and research. It can be said that grapefruit seed extract has antioxidant, antiseptic and antibacterial properties. This technology is in its infancy at the same time. How to seize this opportunity, develop China's packaging industry, improve the technical content of China's packaging, so as 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 commodities is more and more complex, and the functions of packaging are more and more. The wave of high and new technology has pushed packaging to a higher level of development. Modified atmosphere packaging technology will certainly occupy a place in the era of intelligent packaging

information source: Zhonghua printing and packaging

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