Application analysis of the hottest compound modif

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Application analysis of compound modified atmosphere fresh-keeping packaging technology

modified atmosphere packaging is also known as map or cap in foreign countries and modified atmosphere packaging or replacement gas packaging and inflatable packaging in China

the commonly used gases are N2, O2, CO2, mixed gas o2+n2 or co2+n2+o2 (i.e. map). Modified atmosphere packaging technology can be widely used in the preservation of all kinds of food, extending the shelf life of food and enhancing the value of food

I. The Application of CO2 in food packaging

a Swedish company introduced the use of packaging bags, containers and storage rooms filled with 100% CO2 gas to store meat. High concentration of CO2 can hinder the reproduction of aerobic bacteria, molds and other microorganisms, prolong the stagnation period and exponential growth period of microbial growth, and play a role in corrosion prevention and mold prevention. This method can save pork for 120 days without freezing treatment. If it is pressurized again, the storage time will be longer. This method has attracted great attention from meat exporting countries such as the United States and Australia

recently, American experts have adopted new technology to make plastic packaging materials with CO2. That is, using a special catalyst, CO2 and ethylene oxide (or propylene oxide) are mixed in equal quantities to make a new plastic packaging material, which is characterized by glassy transparency and airtightness; Similar to polycarbonate and polyamide resin: it will not completely decompose into gas at 240 ℃; It has the characteristics of biodegradation and will not pollute the environment and soil

China has successfully studied the use of nanotechnology to efficiently catalyze CO2 to synthesize degradable plastics. That is, the catalyst for making plastics from CO2 is "crushed" to the nanometer level to realize the polymerization of catalytic molecules and CO2, so that each gram of catalyst catalyzes about 130 grams of CO2 to synthesize a new packaging material containing 42% CO2. As an environmental protection material with excellent degradability, it has a broad application prospect

II. Application of nitrogen in food packaging

nitrogen (N2) is an ideal inert gas, which has unique effects in food packaging: it does not react chemically with food and is not absorbed by food, which can reduce the oxygen content in the package, greatly inhibit the growth and reproduction of bacteria, molds and other microorganisms, slow down the oxidative deterioration and decay of food, so as to keep food fresh. Nitrogen filled packaged food can also prevent food from crushing, sticking or shrinking into a ball, and maintain the geometric shape, dry, crisp, color, flavor and other advantages of food. At present, nitrogen filled packaging is rapidly replacing the traditional vacuum packaging, and has been applied to fried potato chips and chips, oil cooked food, etc. Being loved by consumers, especially children and young people, nitrogen filled packaging is expected to be applied to more food packaging

N2 is applied in the United States to increase the strength of thin aluminum beverage cans, and nitrogen is dissolved in the beverage before the beverage is canned; After the beverage can is sealed, nitrogen is released from the beverage, forming a pressure on the can wall, making the beverage can equivalent to an inflatable can, thereby increasing the strength of the beverage can, and the effect is remarkable. The canned beverage will not be damaged during transportation, stacking or on the shelf, nor will it affect the quality of the beverage. This method can also be used for beverage packaging made of polyester plastics

in the application of N2, we must pay attention to the purity and quality of N2. The purity of nitrogen separated from compressed air by membrane separation or pressure swing adsorption can reach more than 99.9%. The purity of N2 used in food packaging must reach the pure nitrogen level (i.e. safety level)

III. application of composite gas in packaged food

composite modified atmosphere fresh-keeping packaging is collectively referred to as map packaging internationally. The modified atmosphere fresh-keeping gas used is generally composed of C02, N2, 02 and a small amount of special gases. C02 can inhibit the growth and reproduction of most aerobic spoilage bacteria and molds; O2 inhibits the growth and reproduction of most anaerobic spoilage bacteria; Maintain fresh meat color, oxygen rich respiration and freshness of fresh fruits and vegetables; N2 is used as filling gas. The compound gas ratio is properly selected according to the food type, preservation requirements and packaging materials, so as to achieve the effect of high fresh-keeping quality of packaged food, good nutritional composition, real achievement of original properties, postponement of fresh-keeping shelf life, and Realization of wide-ranging production on the basis of small-scale test and pilot test

composite modified atmosphere fresh-keeping packaging has been widely used at home and abroad

▲ modified atmosphere packaging of fresh fish and shrimp. The deterioration of fresh aquatic 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 alcohol in fish body, softening of fish meat Fish surface bacteria (aerobic produces toxic toxins, endangering 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 and will not make the fish exude; the concentration of O2 is 10% - 15%, which inhibits the reproduction 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 exude plastic film, the package of modified atmosphere packaging of fish The packaging material needs a composite plastic film with high gas barrier, which can be maintained for 15-30 days at a temperature of 0 ℃ - 4 ℃. British tuna is packaged with 35% - 45% CO2/55% - 65% N2 gas. Most manufacturers choose materials with a shelf life of 6 days

the deterioration of shrimp is mainly caused by microorganisms. Its internal enzyme action causes shrimp to blacken. Modified atmosphere packaging can preserve the freshness of Grasscarp. First, shrimp

was soaked in 100mg/l lysozyme and 1.25% sodium bisulfite preservative solution, and then poured with 40% CO2 and 60% N2 mixed gas for a long time exposed to the air in an inflatable adjustable packaging bag. Its shelf life was 22 days longer than that of the control sample, which was 6.5 times that of the control sample

▲ modified atmosphere packaging such as electronic universal experimental machine for poultry and livestock fresh meat

the modified atmosphere fresh-keeping packaging of fresh pork, sheep and cattle should not only keep the original red color of fresh meat, but also be antiseptic and fresh-keeping. The gas in the modified atmosphere packaging is composed of O2 and CO2. According to the different types of meat, the gas composition is different. The gas composition of modified atmosphere packaging of pork is 60% - 70% 02 and 30% - 40% CO2. The shelf life at O ℃ - 4 ℃ is generally 7-10 days (including chilled pork that is cooled at O ℃ - 4 ℃ for 24h after slaughter to lose ATP active substances and become soft, fragrant and palatable). The modified atmosphere packaging of poultry meat is mainly anti-corrosion and fresh-keeping, and the fresh-keeping gas is composed of CO2 and N2. The poultry meat is packaged with 50% - 70% CO2/50% - 30% O2 at O ℃ - 4 ℃ for 14 days

in the modified atmosphere fresh-keeping packaging of meat, the use of high concentration of O2 can keep the fresh meat bright red and bright. In the anoxic environment, the meat is light purple. For example, with CO2, N2 and other fresh-keeping gases, the meat is light purple, and the fresh-keeping period can reach about 30 days. Fresh meat packaging materials also require the use of composite plastic packaging materials with high barrier to gas

▲ modified atmosphere fresh-keeping packaging of baked goods and cooked food products

baked goods include cakes, cakes, cookies, bread, etc., and the main component is starch. Spoilage caused by bacteria and mold, rancidity and deterioration caused by fat oxidation, aging and hardening of starch molecular structure, etc. cause food deterioration. The gas used in the modified atmosphere packaging of this kind of food is composed of CO2 and N2. Cakes without cream can be kept fresh for 20-30 days at room temperature. Moon cakes and pudding cakes can be kept fresh for 60-90 days at room temperature with high barrier composite film

microwave dishes, bean products and cooked meat products of livestock and poultry can be effectively inhibited by filling CO2 and N2. Keep fresh for 5-12 days at 20 ℃ - 25 ℃, keep fresh for about 30 days at room temperature after conditioning and sterilization at 85 ℃ - 90 ℃, and keep fresh for 60-90 days at 0 ℃ - 4 ℃

▲ modified atmosphere fresh-keeping packaging of fresh fruits and vegetables. After harvest, fruits and vegetables can still maintain the metabolism of absorbing oxygen and discharging CO2, while consuming nutrition. Fresh keeping of fruits and vegetables is to reduce the oxygen content in the environment and low temperature storage, reduce the respiratory progress, eliminate the CO2 produced by respiration, and delay the ripening and aging of fruits and vegetables, so as to achieve the fresh-keeping effect. 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, which is conducive to the preservation of fresh environment of fruits and vegetables and maintain the balance of 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 used for litchi preservation and fresh-keeping. Treating litchi fruit with 10%co2+90%n2 and 20%co2+80%n2 for 24hr can not only achieve the purpose of fresh-keeping, but also improve the good fruit rate of the fruit, keep the peel red, and do not affect the nutritional components. Treating with high CO2 and low oxygen conditions combined with ozone (4.3mg/m3 concentration) and using edible thin film can prolong the shelf life of strawberries for 8-10 days

American scientists used modified atmosphere packaging test on mango. Mango was peeled, cut into pieces, packed with oxygen, mixed gas (N2 86%, CO2 10%, O2 4%) and vacuum packaging respectively. The results showed that mango packaged with mixed gas had the longest shelf life. During storage, mango had good color, texture and other appearance effects, and the damage caused by microorganisms was the least

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

source: packaging and printing

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