Commonly used mixed gases and their characteristics in modified atmosphere packaging

People expect food to be fresh, attractive and of high quality at any time, anywhere. To meet these expectations, manufacturers and distributors have to solve huge logistical problems. The high stability of the cargo ensures that it can be transported over long distances. Also, packaged foods are attractive enough for people to buy. Consistent quality (taste, preservation, etc.) is necessary to gain strong customer loyalty. The freshness and perishability of perishable commodities such as meat, fish and seafood depends not only on the ingredients themselves, but also on environmental influences. Microbial and biochemical reactions are responsible for spoilage of perishable foods, which is a particular concern for fresh meat and seafood. The spoilage begins after slaughter, which is difficult to stop because the microorganisms have already reached it. A well-known method that has the potential to reduce or slow its activity is freezing. Of course, frozen foods are not considered fresh products. In addition, the goods must be constantly frozen during transportation, which is a high-cost and high-investment method compared to MAP packaging. A large number of practices have proved the remarkable results after the application of modified atmosphere packaging:

A Better product quality and longer shelf life

- Prevent oxidation, spoilage and discoloration

- Improved atmosphere can inhibit bacterial and fungal growth characteristics

- Mechanical protection for fragile products

- Maintains the appearance, smell, flavour and texture of the product thus maintaining its freshness

- Extended shelf life, can replace food transportation methods, greatly reduce transportation costs

2 How to apply MAP?

Due to the different characteristics of the food itself and the different conditions encountered in the transportation and sales of food, the requirements for packaging vary greatly. There are many factors to be considered when using the modified atmosphere packaging technology for food, mainly including the following four elements. (1) Gas replacement

Use a vacuum pump to extract the air in the packaging bag or box to form a certain degree of vacuum, and then fill it with mixed fresh-keeping gas. After completing the process of gas replacement, the residual oxygen in the package can be less than 1%.

(2) Gas mixing

1 Commonly used mixed gases and their characteristics

1) CO2 CO2 can inhibit most aerobic bacteria and molds. Without a doubt, carbon dioxide is the most important gas for gas conditioning in food packaging. Generally speaking, the higher the carbon dioxide concentration, the longer the perishable food will have. However, during the packaging process, fat and water can easily absorb carbon dioxide. If the concentration of carbon dioxide is too high, it will also affect the taste of the food and consume the humidity and concentration of the food (called the vacuum effect). Therefore, it should be carefully considered! As for how long the shelf life and how much consumption depends on the amount of carbon dioxide. If the purpose of carbon dioxide is to inhibit the growth of bacteria and mold, a concentration of at least 20 % is recommended.

2) N2 Nitrogen is an inert gas used to expel the air, especially oxygen, in the package. It is also used in perishable foods as a filling gas, similar to carbon dioxide. Nitrogen reduces the vacuum effect and is also a natural part of the air.

3) O2 Oxygen is a very important gas for living organisms, and also supports the deterioration of perishable foods. It is the condition for the growth of aerobic microorganisms. In general, oxygen is not used in MAP, but in some cases, quantitative oxygen yields fairly good results. It makes perishable foods look natural (the effect of freshness). It allows food to breathe, especially fruits or vegetables. It inhibits anaerobic microorganisms in various fish and vegetables.

2 How to mix accurately?

The classic gas mixer adopts the principle of double equal pressure and adjusts the proportion of various gases through proportional valves. The gas ratio and accuracy are not affected by changes in the pressure of the gas source and fluctuations in the gas flow, and provide stable and accurate gas supply. With the advancement of science and technology, the KM, MG series gas mixers produced by German WITT company can realize intermittent and continuous simultaneous operation of one device, and the accuracy of the mixed gas ratio is better than 1%. It has a good performance The mixer has also been loved by world-renowned packaging machine manufacturers, and has reached a global strategic partnership with several packaging machine companies such as MULTIVAC, WEBOMATIC, and ILAPAK.

(3) Packaging materials:

1 Commonly used packaging materials are divided into

1) Polyolefin classification: polyethylene (PE) and polypropylene (PP).

2) Vinyl polymer categories: ethylene vinyl acetate copolymer (EVA), polyvinylidene chloride (PVC), polyvinylidene chloride copolymer (PVDC), ethylene-vinyl alcohol copolymer (EVOH),.

3) Polystyrene (PS)

4) Polyamide (PA)

5) Polyester (PET)

2 Attention should be paid to the selection of packaging materials

- The packaging box should be made of high-barrier material, and the boxed film will vary according to the characteristics of different products.

- The packaging box should be highly effective in terms of moisture permeability, oxygen permeability and light transmission;

- The common characteristics that packaging films should have are anti-fogging, minimum light transmittance, and different products with different air permeability. Choose films with different characteristics. For example, the respiration of fruits and vegetables will affect the proportion of mixed gas, and the air permeability of the barrier film must be relied on. to maintain the balance of the gas ratio;

(3) Storage environment: The best storage environment for modified atmosphere packaging is refrigeration. At present, the temperature of refrigerated food in supermarket refrigerated display cabinets is about 33% higher than 7°C, and about 5% is higher than 13°C. The average temperature of household refrigerators 10 to 13°C. Obviously, the current cold chain conditions cannot meet the refrigerated temperature and condition requirements of modified atmosphere packaging or vacuum packaged refrigerated food. The recommended refrigeration temperature for many non-breathing refrigerated fresh foods (such as livestock, poultry, and fish) is 0-2 °C, and the recommended refrigeration temperature for many breathing refrigerated fresh foods (such as apples, strawberries, mushrooms) is 0-5 °C. The ambient temperature of storage also directly affects the preservation effect of food.

Zhejiang Mingwei Machinery Co., Ltd., established in 2012, is a professional intelligent fresh-keeping packaging equipment manufacturing enterprise integrating research, development and production. Mingwei people always keep in mind to promote the intelligent development of global packaging equipment. Researched and developed advanced intelligent control food modified atmosphere packaging machine, body skin packaging machine, full line air conditioning / body skin packaging equipment, soft film stretch vacuum packaging equipment, thermoforming modified atmosphere packaging equipment, thermoforming body packaging equipment, etc. . In order to meet the domestic market's demand for high-quality, cost-effective, and reliable products, Zhejiang Mingwei Machinery Co., Ltd. focuses on the construction and development of the domestic market while developing and consolidating the European and American markets. More professional technical support, better service system and sincere spirit of cooperation, serve customers wholeheartedly and help customers create greater product value