Sealing - No Air, No Bacteria

In the industrial production of canned goods , such methods of food preservation as hermetic and vacuum packaging are widely used, which contribute to the prevention of the penetration of bacteria from the air into the processed product . Thanks to vacuum packaging, aerobic bacteria remain without oxygen, as a result of which they die.

With atmospheric conservation and replacing the gas atmosphere with an inert one, the product (for example, salad) is stored in the package without losing its shape. And as a result of replacing oxygen with nitrogen, the insects present in the product are destroyed.

Also, sealing is one of the most responsible steps in making canned goods by any other method. This operation involves hermetically closing the can with canned food in order to isolate the product from the external environment, which, in turn, prevents microorganisms from entering the can.

The essence of the process is the hermetic connection of the lid to the body of the canned food container , which isolates the contents from the external environment to create sterile conditions.

When sealing and sterilizing canned goods , high pressure is created, which threatens their integrity and can lead to spoilage. In addition, in the presence of oxygen during sterilization, the nutrients of the product are destroyed , and the inner surface of the metal container is also corroded.

Air is removed from cans to eliminate or reduce pressure. This process is called exhaustion. The air will be removed from the free space of the can, not filled with the product , and the spaces between the parts of the solid contained, as well as the liquid part in which it can be dissolved.

This process can be carried out by 2 methods: thermal and mechanical.

Exhausting by thermal method consists in heating cans with the product with steam, which displaces air from the container. At the same time, the product itself is heated to 80°C. Filling the jar with hot filling, at a temperature not lower than 75°С, is also one of the varieties of thermal exhaust.

The mechanical method consists in sucking out air from the can with a vacuum pump of rolling machines.

To more effectively remove air from cans, a combination of thermal and mechanical exhaust methods is used. After this procedure, the cans are immediately sealed.

Usually, at home, canned goods are closed with tin lids using a manual rolling machine.

In the production of canned goods in the industry, the rolling of cans is carried out before sterilization. And at home, jars are sterilized with just covered lids, and rolled after heat treatment. If you sterilize hermetically closed jars, the lids will be torn off due to the high internal pressure of water vapor and air.

When cooling canned goods after heat treatment, a vacuum is created inside the cans, as a result of which the lids are tightly pressed against the rubber gasket, which ensures tightness.

Also, glass cans can be closed with special glass lids with rubber gaskets and steel clamps. In this case, a rolling machine is not needed. This method allows you to use the lids and clamps for several years (at that time. As tin lids are usually disposable).

Also, you can close banks with plastic lids. However, they are not suitable for all canned foods , as they do not provide tightness. They are usually used for jars with jam, marmalade, pickles.