Frequently Asked Questions
Why is coffee oily ?
Arabica and Robusta coffee contain different levels of lipids, 0.2 to 0.3% present in a waxy layer surrounding and protecting the bean. The total lipid content of Arabica is around 15%, but levels up to 17% have been measured. In Robusta the average is, according to different authors, 10 or 15%, but can be as low as 7%. The lipids in green coffee are as follows:
|Constituent||% Total lipids|
|Free fatty acids||0.5 - 2.7|
|Diterpene esters||15 - 18.5|
|Free diterpenes||0.1 - 1.2|
|Triterpenes, sterols, and sterol esters||1.4 - 3.2|
|5-Hydroxytryptamides and derivatives||0.3 - 0.7|
|Tocopherols||0.3 - 0.7|
It is noted that the fatty acid composition differs between the outer wax and the bean oil fraction.