Oil and fat containing food items are flushed with nitrogen. Why?
Oil and fat containing food items are flushed with nitrogen to prevent them from getting oxidised. When fats and oils are oxidised, they become rancid, leading to a change in their smell and taste.
By flushing the bags with nitrogen, manufacturers create an environment that stops oxidation. This method is an effective way to preserve the quality of the food, similar to using airtight containers or adding antioxidants, ensuring the items do not spoil.
Explanation
The answer is derived from the section '1.3.2 Rancidity' in the provided text. The text explicitly states that chips manufacturers flush bags with nitrogen to prevent oxidation. It further explains that oxidation causes fats and oils to become rancid, changing their smell and taste.