Question

Why do oils and oily foodstuffs undergo a change in their smell and taste if kept for a long time? Give its causes and suggest a method to prevent it.

Answer 1

1. Oils and oily foods undergo a change in their smell and taste if kept for a long time due to rancidity.
2. Rancidity is the natural oxidative chemical degradation of oils.
3. Oils undergo two types of degradation:
   1. Oxidation: It is the degradation of oils in presence of oxygen and light to produce hydrogen peroxide and aldehyde.
   2. Hydrolysis: It is the degradation of oils in presence of water to convert the esters into free fatty acids.
4. Methods to prevent rancidity;
   1. Keeping oils and oily food in an airtight container.
   2. Adding suitable antioxidants.
   3. Avoid contact with moisture and air.
   4. Avoid exposure to high temperatures and light.