The Exhaust Tunnel (or sometimes Exhauster) is a pre-heating stage primarily used in canning (glass jar, tin can, or pouch) production lines, applied to remove air and gases inside the packaging just before the sealing process.
This process is critical for the success of canned food production and the product's shelf life.
- It expels trapped air within the product tissues (vegetables, fruits) and dissolved gases within the filling liquid (brine/syrup) by causing them to expand due to the increase in temperature.
- Oxygen causes food corrosion (rusting inside the tin can), discoloration (browning), and vitamin loss. The removal of oxygen prevents these spoilage reactions.
- After the air and gases inside the packaging are expelled, the lid is hermetically sealed while hot.
- KAfter the lid is sealed, the can or jar is allowed to cool. During cooling, the air and gases, whose volume shrinks, ensure the formation of a vacuum inside the packaging. This vacuum keeps the lid depressed and ensures the packaging is resistant to external factors.
- Packages sealed without sufficient exhausting carry the risk of swelling (bombage) due to the expanding air inside during the subsequent high-temperature pasteurization or sterilization (Autoclave) stage. Exhausting eliminates this risk.
