Some beverages contain components that are very susceptible to oxidation. This is evidenced by the color and flavor changes that occur during distribution. As little as 10 ppm of oxygen, given enough elapsed time during distribution, has been known to cause these oxidation changes.
Deoxygenation consists of stripping the excess oxygen dissolved in the liquid by injecting nitrogen or carbon dioxide in the form of tiny bubbles. Using a concentration gradient, these bubbles force the dissolved oxygen into the gas phase which is then vented out from the liquid.
This can reduce the residual oxygen retained in the beverage to as little as 1 to 3 ppm, greatly extending the quality life of the beverage.