Butter is a mixture of triglycerides
of several different fatty acids, so no single chemical structure can be drawn.
A list of the more common fatty acids in butter is given below. The glycerides break down after some time, releasing
the free fatty acids. The butyric acid released is responsible for the nauseating smell of rancid butter. (The caproic
acid also smells wretched).
The color of butter comes from the presence of small amounts of carotene.
| Fatty acid | Structure | % total fatty acid in butter |
| oleic acid | CH3(CH2)7CH=CH(CH2)7COOH | 31.9 |
| myristic acid | CH3(CH2)12COOH | 19.8 |
| palmitic acid | CH3(CH2)14COOH | 15.2 |
| stearic acid | CH3(CH2)16COOH | 14.9 |
| lauric acid | CH3(CH2)10COOH | 5.8 |
| butyric acid | CH3CH2CH2COOH | 2.9 |
| caproic acid | CH3(CH2)4COOH | 1.9 |
| capric acid | CH3(CH2)8COOH | 1.6 |
| caprylic acid | CH3(CH2)6COOH | 0.8 |
| linoleic acid | CH3(CH2)4CH=CHCH2CH=CH(CH2)7COOH | 0.2 |
| linolenic acid | CH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7COOH | 0.1 |