The deterioration of fresh aquatic products and marine fish is mainly caused by bacteria, which decomposes the trimethylamine oxide of the fish to release the trimethylamine which is rotten, the fatty acid of the fish is oxidized and rancid, the enzyme of the fish is softened, and the bacteria on the surface of the fish (aerobic Escherichia coli) , anaerobic Clostridium) produces poisoning toxins, endangering human health. The gas used for modified atmosphere packaging of fish is composed of CO2, O2 and N2, wherein the concentration of CO2 gas is higher than 50%, inhibiting the growth of aerobic bacteria and mold without causing exudation of fish; the concentration of O2 is 10%-15%. Oxygen bacteria reproduction. The fish's cockroaches and internal organs contain a large amount of bacteria, which must be removed, cleaned and disinfected before packaging. Because CO2 easily oozes out plastic film, the packaging material for fish modified atmosphere packaging needs to use a composite plastic film with high gas barrier property, which can be maintained for 15-30 days at 0 °C-4 °C. British tuna uses 35%-45% CO2/55%-65% N2 gas fresh-keeping packaging for 6 days.
Since the 1930s, fresh beef and mutton has been put into large bags for storage and transportation, but the large-scale commercial application of this technology has only begun since 1970. In 1979, Mark & ​​Spencer of the United Kingdom introduced MAP meat products, which were applied to fish and ham two years later. Since 1955, foreign countries have studied the fresh-keeping of fruits and vegetables. Marcelan of the Plant Physiology Laboratory of the Gerhard National Research Center in the United States began to study various PE membranes for storing apples and pears, and systematically studied the changes of oxygen and carbon dioxide in the storage environment, and published a research report in 1960. And called the physiological packaging storage. The formula, thickness and specification of the wrap film are determined according to the biomodulus of the fruit respiration. Under the specific temperature conditions, the gas component in the bag is maintained by the double effect of the PE film transmitting O2 and CO2.
China's air-conditioning packaging began in the 1990s. In 1988, the National Agricultural Products Preservation Engineering Technology Center developed 24 formulas for PVC wrap for fruits and vegetables, from which 32 varieties were selected, and 47 specifications were used for cucumber, celery, grapes, and apples. And the practical application of plastic wrap bags such as pears. In recent years, atmosphere-adjusting packaging technology has become a hot topic of research. The use of modified atmosphere packaging for fruits and vegetables is not only safe and effective, but also simple to operate. It has become the focus of research at home and abroad in recent years and is widely used.
Synchronous with the development of modified atmosphere packaging technology is the atmosphere packaging equipment. High-efficiency modified atmosphere packaging production equipment The main equipment for food modified atmosphere packaging production is vacuum modified atmosphere packaging machine and gas proportional mixer. At present, China's packaging production enterprises have been able to provide various types of bag or box packaging machines, fully automatic vacuum modified atmosphere packaging machines and gas proportional mixers for food enterprises. For example: Shanghai Jugang Machinery Manufacturing Co., Ltd., which develops bag-and-box packaging based on the production of vacuum-inflatable packaging machinery products through technical cooperation with the School of Mechanical Engineering and Automation of Shanghai University and the Food College of Shanghai Fisheries University. The series of modified atmosphere packaging machines and gas proportional mixer products. The developed product has a box packaging ZQT-1.
D400 type, MAP-200 type automatic air-conditioning packaging machine adopts programmable (PLC) and built-in gas mass flow ratio mixer, various packaging parameters such as: gas mixing ratio, gas replacement time, heat sealing temperature and time, sealing film Traction and mold movement time control can be automatically controlled by touch screen setting, which is easy to operate.
Recently, the United States has further strengthened its research on a new generation of modified atmosphere food packaging systems. Ilapak's newly developed high-speed modified atmosphere packaging Delta3000LD (LongDwell) line packaging machine can pre-program up to 64 production solutions to ensure quick and easy adjustment of package size. It is also characterized by the ability to precisely control the inflation, the high-tightness of the sealing port for long-term maintenance, and the quality control device of the bag when there is no product.
At the same time, Multivac has developed a new type of tray sealing machine for poultry and packaged ready-to-eat meat products. The new technology encapsulates the product in a shallow tray and guarantees a complete seal while providing a better visual effect. Rovema Packaging Machinery's range of air-conditioned flexible pouches and pillow packs are suitable for a wide range of products including coffee, breakfast cereals, and baked goods. Its vertical form / fill / vacuum / aerated / sealing system can handle liquid, viscous, granular or solid products; pillow packaging machine speeds up to 180 bags / minute, from single package to large food packaging Can be produced.
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 experimental and research stage. It can be said that this technology is in its infancy. How to seize this opportunity, develop China's packaging industry, improve the technical content of China's packaging, to adapt to the requirements of the new form of international economics, is the problem faced by every packaged person. With the changes of the times, the variety of goods is more complicated and complex, and the functions of packaging are more and more. The wave of high-tech has pushed packaging to a higher level of development, and atmosphere-adjusting packaging technology will surely have a place in the era of intelligent packaging.