Vacuum packaging of food products globally became common in use in late 1950’s and accepted by the market as a type of packaging to keep the food without degradation. Taking air out of the pack allowed food products manufacturers to offer a considerable shelflife for without degradation as experienced with other forms of preservation, particularly those involving the use of high temperatures. At the beginning, vacuum packaging was used for dairy and meat. Experiences showed that some products lost their freshness under vacuum pack like natural cheese because of its sticky apperance when the pack first opened, also fresh meat lost its red color because of the missing oxygen. Beside, meat slices sticks each other due to vacuum process. Therefore a new type of packaging need is arised and this lead to Development of modified atmosphere packaging (MAP) machines in the style of thermoforming or chamber machines. Thermoform Modified Atmosphere Packaging Machinery did not require a new invention however it has been a development of established packing systems. With the increasing demand for improved seals and efficiency of flushing increased, thermoform machine manufacturers turned their attention to developing the MAP machines. Efficiency and succes of a modified atmosphere packaging (MAP) system can be determined by the relation between gas, packaging material and the packaging machine. Many food products undergo spoilage through the process of oxidation. This can be retarded by the removal of the oxygen and replacing it with an inert gas. The most commonly used purging gases are carbon dioxide (CO2) and nitrogen (N2).
The other important point is choosing the packaging material for MAP (Modified Atmosphere Packaging) operation. Cost effective materials must have the essential physical properties of low water vapour transmission, high gas barrier, mechanical strength to withstand machine handling and subsequent storage and distribution in the finished pack format, as well as having the capability of giving high integrity seals to ensure retention of gas within the pack until opened by the consumer. Laminations of polyester and polyethylene, nylon and polyethylene, polyvinyldichloride, orientated polypropylene and many more are in common use.
Last important choice is the thermoform packaging machinery itself. Packaging machinery has the importance at the same level with packaging material and gas. Thermoform packaging machine should be working reliable, at a sustainable speed, making satisfactory sealing line at the package, vacuuming the air to outside and flushing the gas at an acceptabel level with a repeating process. From this point of view, forming unit, vacuum chamber, sealing performance, gas flushing unit is very important in thermoform packaging machines.
