What is modified atmosphere packaging machine?
Modified atmosphere packaging machine
, which also refers to the air-conditioned freshness packaging machine
, air-conditioned packaging machine, freshness locking packaging machine, etc. MAP packaging machine
is a food preservation equipment with a gas replacement function, in other words, the food packaging equipment using a non-polluting gas mixture to lock the fresh food can extend the freshness period of food. Aerosol packaging machine is generally used for cold chain food preservation.
Working principle of modified atmosphere packaging machine
Automatic modified atmosphere packaging equipment uses fresh gas to lock food protection, it works by vacuuming the air inside the box, the air out, and then filling it with a certain proportion of fresh gas, and after the film, thermoplastic sealing, film cutting and other aspects of the package and become.
The preservation gases that can extend the shelf life of food are usually three gases - oxygen, nitrogen, and carbon dioxide - each of which plays a different role.
Composite modified atmosphere packaging machine preservation principle
The principle of composite modified atmosphere packaging machine is to use composite preservation gas (2-3 kinds of gas according to the food characteristics of the proportion of the mixture), the box or bag of air replacement, change the box (bag) in the external environment of the food, to inhibit the growth of bacteria (microorganisms) to slow down the metabolism of fresh fruits and vegetables, to extend the shelf life or shelf life of the food. Thus, prolonging the freshness or shelf life of food.
Air-conditioning preservation gas is generally composed of carbon dioxide (CO2), nitrogen (N2), oxygen (O2), and a small number of special gases. CO2 gas has the effect of inhibiting most of the growth and reproduction of spoilage bacteria and molds, and is the main bacteriostatic component of the protective gas; O2 has the effect of inhibiting most of the anaerobic spoilage bacterial growth and reproduction, to maintain the color of the fresh meat and fresh fruits and vegetables to maintain the aerobic respiration, maintain the freshness of the role; N2 is an inert gas, and food does not work, as a filler gas, with CO2, O2 and special gases to form a composite preservation gas. For different foods and fruits and vegetables, the composition and proportion of freshness preservation gas are also different.
Realization of air-conditioned packaging
According to the different packaging materials, pneumatic packaging is usually divided into 2 categories.
Flexible film inflatable packaging
External or internal vacuum packaging machines usually include single/double chamber vacuum packaging machines and fully automatic stretch film vacuum packaging machines. This type of MAP packaging equipment can generally be retrofitted with an inflatable function to be filled with protective gases to extend the shelf life of the food or to prevent the food from being crushed.
Rigid box air-conditioned packaging
Generally, air-regulated packaging means rigid box air-regulated packaging. Put the product into the air-conditioned box, the air-conditioned box into the vacuum chamber of the air-conditioned packaging machine, the vacuum pump pumping vacuum to make the vacuum chamber reach the lowest vacuum and residual oxygen, and then filled with a single or mixed gas, and then heat-sealed with sealing film. This kind of packaging method is also known as air conditioning sealing box locking freshness packaging by many people.
Why use a modified atmosphere packaging machine for freshness packaging?
Although traditional vacuum packaging can extend the shelf life of food to a few months or even 2 years, vacuum-packed food generally needs to be frozen to preserve, these post-processing process determines that the vacuum packaging is not suitable for packaging fresh food, such as cold meat, vegetables, fruits, and so on.
a. The main function of the gas-conditioning lock fresh packaging is to adjust the gas composition within the package structure, to maintain the respiratory activity of fresh food, inhibit the growth and reproduction of microorganisms, to ensure that the food in 0 degrees Celsius and above the shelf life of low-temperature refrigeration conditions can be extended to 7-15 days, and does not change the fresh food, "Fresh" this basic feature. It should be clear that the products after air-conditioned packaging can also be sterilized at high temperatures and kept frozen. But for fresh meat, aquatic products, vegetables, and fruits, etc., the most important significance of the gas-regulated packaging is the preservation of freshness in a low-temperature non-freezing environment.
b. Products packaged by a modified atmosphere packaging machine can be labeled to show the company's logo and shape the brand image.
c. The shelf life of gas-conditioned packaged products is extended, which can effectively extend the distribution range of fresh products, expand the sales area, increase brand awareness, and increase turnover and profits for the enterprise.
d. The use of vacuum packaging can effectively reduce food waste, and has important social significance.
Gases used in modified atmosphere packaging machines
MAP machine packaging requires the filling of gas cartridges with single or mixed gases. To guarantee the quality of the gas-conditioned packaging, these gases need to be of extremely high purity, usually 99.99 percent and above. The gases are stored in cylinders, equipped with pressure-reducing valves, and connected to the filling line of the gas conditioning packaging machine via a connection mechanism. In the case of gas mixtures, a gas mixer is also required, where the gas is mixed to a specific ratio before it enters the packaging machine.
The most common gases used in gas-conditioned packaging are O2, CO2, and N2. The choice of gases and their mixing ratios must be based on the characteristics of the foodstuffs to be packaged. These gases are used individually or in combination to find the optimal solution, balancing the need to extend the shelf life of the food with the need to maintain the best possible flavor. Some other gases may also be used in gas-conditioned packaging.
Nitrogen is an inert gas (does not react with food) and has no odor, taste, or color. Nitrogen has a lower density than air, is non-flammable, and has low solubility in water (0.018 g/kg at 100 kPa, 20°C) and other food ingredients.
Nitrogen effectively inhibits the growth and multiplication of aerobic microorganisms and therefore slows down the resulting food spoilage. However, nitrogen does not prevent the growth and multiplication of anaerobic bacteria.
Based on its low solubility in food, nitrogen can be used as a filler gas in packages to prevent package collapse by adding enough N2 to the gas mixture to balance the reduction in gas volume due to the solubility of CO2 in water. Packaging collapse is caused by foods containing high levels of moisture and fat, which absorb CO2 from the package, resulting in a reduction of gas inside the package, a decrease in air pressure, and an imbalance of air pressure inside and outside of the package, which can lead to packaging collapse. In MAP gas-conditioned packaging for dry snack products, it is common to fill the package with 100 percent nitrogen for protection against oxidative rancidity and crush protection.
Carbon dioxide (CO2)
Carbon dioxide is a colorless gas with a slightly irritating odor at very high concentrations. It is an asphyxiant and is slightly corrosive in the presence of moisture. CO2 is soluble in water (1.57 g/kg @ at 100 kPa, 20° C) to form carbonic acid (H2CO3), which increases the acidity of the solution and lowers the pH.
The solubility of CO2 increases with decreasing temperature. Therefore, the anti-microbial activity of CO2 is significantly higher at temperatures below 10°C than at temperatures of 15°C or higher, which is important for the aerated packaging of food.
The high solubility of CO2 can cause the package to collapse due to the reduction in headspace volume. Such packages then need to be filled with nitrogen to counterbalance this.
CO2 inhibits the growth of most aerobic bacteria. Generally, higher levels of CO2 mean a longer shelf life. However, many high-moisture and high-fat foods absorb CO2, and excess CO2 in air-conditioned packaging can lead to package collapse, flavor contamination, and moisture loss. It is therefore of the utmost importance to find a balance between the desired shelf life and the degree of negative effects that can be tolerated in industrialized gas-conditioned packaging. A minimum of 20 percent CO2 in the gas mixture is recommended to control bacterial growth.
Oxygen is a colorless, odorless gas that readily reacts with foodstuffs in oxidation and supports combustion. It has a low solubility in water (0.040 g/kg, 100 kPa, 20°C).
Oxygen promotes several types of spoilage reactions in food, including fat oxidation, browning reactions, and pigment oxidation. Most common spoilage bacteria and fungi require oxygen to grow. Therefore, to prolong the shelf-life of food, air-conditioned packages should contain a low concentration of residual oxygen.
It should be noted that in some foods, low concentrations of oxygen can lead to quality and safety problems (e.g. unfavorable color change of red meat pigments, senescence of fruits and vegetables, growth of food-poisoning bacteria), which must be taken fully into account when selecting the gaseous composition of packaged foods. There are usually good reasons for the presence of oxygen in gaseous packaging, including maintaining the freshness and natural color of the food (i.e. red meat); maintaining the respiration of fresh vegetables and fruit; and inhibiting the growth of anaerobic organisms (some vegetables and fish).
Carbon monoxide (CO)
Carbon monoxide is a toxic, flammable, colorless, odorless gas. It is stable up to 400°C in terms of decomposition into carbon and oxygen. Studies have shown that the use of carbon monoxide (CO) in MAP air-conditioned packages containing high levels of CO2 extends shelf life and maintains the bright red color of the meat. Please note that the use of CO in air-conditioned packaging is not permitted in Europe.
Gas mixing ratios for modified atmosphere packaging machine for commonly used products in gas-conditioned packages
For MAP machine packaging that needs to be filled with a mixture of gases, the mixing ratio of the different gases is the focus of all the work. The optimum gas ratio may vary from product to product, and even from brand to brand for the same product. The data in the table below is for reference only. Specific tests are required to determine the gas-conditioned packaging for specific products.
|Red meat (fresh pork, beef, lamb, etc.)||70-80% oxygen, 20-30% carbon dioxide
|Poultry, chicken, duck and goose meat||0-20% oxygen, 30-40% carbon dioxide, 60-70% nitrogen
|Low-fat fish||40% carbon dioxide, 60% nitrogen
|High-fat fish, shrimp, shellfish, etc.||30% oxygen, 40% carbon dioxide, 30% nitrogen
|Cooked, smoked, or barbecued meat||30-40 percent carbon dioxide, 60-70 percent nitrogen
|Fresh fruit and vegetables||5% oxygen, 5% carbon dioxide, 90% nitrogen
|Dried fruits||Nitrogen 100 percent
|Boxed lunches, etc.||30% carbon dioxide, 70% nitrogen
|Baked goods||Carbon dioxide 0-30 percent, nitrogen 70-100 percent
|Fresh pasta (fresh noodles, etc.)||50% carbon dioxide, 50% nitrogen
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