What term describes the unpleasant taste or odour that fats and oils develop over time?

The term that describes the unpleasant taste or odour that fats and oils develop over time is rancidity. Rancidity occurs when fats and oils break down due to exposure to air, light, or heat, leading to the formation of free fatty acids and other compounds that impart a foul taste and smell. This breakdown process can be accelerated by improper storage and is a significant concern in food preservation.

Rancidity is specifically linked to the chemical reactions involving triglycerides, particularly oxidation, where unsaturated fats are more susceptible. While oxidation is a factor in rancidity, the term itself specifically refers to the resulting degradation of fats rather than the broader concept of the reaction. Understanding rancidity is vital for ensuring the quality and safety of food products, especially those rich in fat, like oils, butter, and processed snacks.

Other terms like fermentation and decomposition refer to different processes involving the breakdown of organic materials, primarily related to bacteria or mold activity, and do not specifically apply to the changes that fats and oils undergo.