What are mixed triglycerides and how do they differ from simple triglycerides?

Triglycerides are esters formed by the combination of one molecule of glycerol with three fatty-acid molecules. They are categorized based on the composition of these fatty-acid radicals.1

Simple vs. Mixed Triglycerides

• Simple Triglycerides: These occur when a glycerol molecule is combined with three identical fatty-acid molecules. An example is tripalmitin, which consists of glycerol combined with three molecules of palmitic acid.1
• Mixed Triglycerides: These are the most common type found in nature. They occur when a glycerol molecule is combined with two or three different types of fatty acids. For instance, stearodipalmitin contains two palmitic acid radicals and one stearic acid radical, while oleopalmitostearin contains one radical each of oleic, palmitic, and stearic acids.12

Because mixed triglycerides contain different fatty-acid radicals, they can exist in various isomeric forms depending on the arrangement of these acids on the glycerol backbone. A mixed triglyceride with three different acids can have three isomeric forms, whereas one with two identical acids and one different acid has two.1