In this lesson, you will learn about different types of oils from plants and animal fats.

Chemistry of Oils and Fats

From a chemical point of view, oils and fats are esters composed of three fatty acid units. They belong to the lipids category and serve as an energy source and storage in plants, as well as solvents for fat-soluble vitamins and insulators in the bodies of animals. Plants often store oil in seeds and sometimes in the fruit flesh. In animal bodies, fat is stored in adipose tissue, from which it can be extracted.

Oils and fats have the same general chemical structure, but oils are liquid under standard conditions (25°C), while fats are solid. Often, oils are of vegetable origin, and fats are of animal origin.

Oils and fats are mixtures and do not have a specific melting point but a melting range. They are insoluble in water.

Triglyceride by Wolfgang Schaefer, translated by HOOU (CC BY-SA) 

Vegetable oils often occur as triglycerides (officially named triacylglycerol), which are esters of glycerol with three fatty acids.

Fatty acids are composed of carbon, hydrogen, and oxygen. They consist of long hydrocarbon chains with an attached carboxylic group (COOH). The carbon chain always has an even number of carbon atoms (e.g., 8, 10, 12, etc.) and ranges from 8 to 24. The figure below shows a simple triglyceride. In nature, oils and fats are made up of mixed triglycerides, which contain three different fatty acids with varying chain lengths (12 to 24 carbon atoms). Fatty acids can be classified as saturated or unsaturated.