Vacuum and Gas Flushing Machines

Vacuum Skin Packaging Machines

The principle of the vacuum skin packaging system utilizes a top and base web of material. However, it differs from the vacuum thermoforming machine in that no forming dyes are required. The product is placed on the lower web which may be left flat or formed to suit the product if desired, before being indexed into the chamber of the machine. The top web, which has been preheated to improve its flexibility, is draped over the cheese portions utilizing the product as the dye and using minimum pressure. The air is removed by vacuum and the product is fully encased in a protective second skin before heat sealing the top and bottom webs.

Gas Flushing Machines

This kind of packaging machines is also known as “Modified Atmospheric Pack”, and the machine uses two reels for packing the cheese as described in the form-fill-seal. After evacuating the air from the vacuum chamber, it is then replaced by a controlled mixture of gas (carbon dioxide, nitrogen or a combination of these). Thus this system is referred to as gas-flushing. Thus this system prevents the spoilage of cheese during intermediate storage prior to retailing.

In practice carbon dioxide is widely used, compared with nitrogen as gas flushing unit, because it reacts with the moisture in the cheese to producer carbonic acid and so gives the product a neat snug appearance similar to a vacuum pack. Carbonic acid further serves as a mould inhibitor.