Live practice

Oils and fats react with oxygen and become rancid, producing an unpleasant smell and taste. Nitrogen is comparatively unreactive. Flushing the package with nitrogen removes most of the oxygen and creates an inert atmosphere, slowing oxidation and increasing the shelf life of the food.

(a) Corrosion is the slow damage of a metal caused by reaction with substances such as oxygen, moisture or acids in its surroundings. For example, iron reacts with oxygen and moisture to form reddish-brown rust (hydrated iron(III) oxide).

(b) Rancidity is the oxidation of fats and oils that produces an unpleasant smell and taste. For example, butter or fried food left exposed to air for a long time becomes rancid. Airtight containers, antioxidants and nitrogen flushing slow this process.