Vacuum in canned food

Wide arrays of canned foods are available in supermarkets today, and for many families, these foods can help make quick and convenient meals.

In food processing, objective of exhausting containers/can is to remove air so that the pressure inside the container following heat treatment and cooling will be less than atmospheric.

Vacuum in the can may be obtained by the use of heat or by mechanical means. The tomatoes may be preheated before filling and sealed hot. For products that cannot be preheated before filling, it may be necessary to pass the filled containers through a steam chamber or tunnel prior to the sealing machine to expel gases from the food and raise the temperature.

There are other reasons for having a vacuum in canned foods. It helps preserve color, flavor, and vitamins. Oxygen in the headspace is usually detrimental. By reducing the oxygen content a good vacuum helps prevent internal can corrosion.

The dark substance which sometimes occurs on the inside of canned seafood consists in part of iron oxides. Without a vacuum, the pressure within a can, during processing, become high enough to cause buckles or strains. The reduced internal pressure (vacuum) helps to keep the can ends drawn in, reduces strain on the containers during processing, and minimizes the level of oxygen remaining in the headspace. It also helps to extend the shelf life of food products and prevents bulging of the container at high altitudes.
Vacuum in canned food