Coffee lipids

The lipids of coffee play an important part in the storability of roasted coffee. During storage the lipids can be oxides if oxygen is present and it changes the aroma of coffee, too.

 The total lipid content of coffee varies with the species from about 7 to 17%, with average values of about 15% for arabica and 10% for robusta types.

The largest fraction consists of liquid coffee oil, which is found in the endosperm. Coffee oil is composed mainly of tricylglycerols as well as fatty acids in similar quantities to those found in common edible vegetable oils. About 0.24% (i.e. between 1-2% of the total lipid) is referred to as ‘coffee wax’.

The lipid composition of green coffee beans is as follows:
Triacylglycerol 75.2%
Diterpene esters 18.5%
Free diterpenes 0.4%
Sterol esters 3.2% Free sterols 2.2%
Phosphatides 0.1-0.5%
Carboxylic acid-5-hydroxytryptamides 0.6-1.0%
Tocopherols 0.04-0.06%

The main free fatty acids in the oil are linoleic acid (43-46% of the acids) and palmitic acid (30-35%). Oleic, stearic, arachidic and linolenic acids are also present in lower proportions. The presence of free fatty acid is evidently the most important factor affecting flavor formatting during roasting.

Both green and roasted coffee oils are used industrially, the former in the cosmetic industry and the latter in food applications such as flavorings.
Coffee lipids

Triglycerides in coffee

The lipid content of green arabica averages some 15% on a dry basis, whilst robusta contains much less around 10%. Most of the lipids the coffee oil, are located in the endosperm of the coffee bean while only a small amount, the coffee wax is in the outer layer.

Coffee oil is composed mainly of triglycerides with fatty acids in proportions similar to those found on common edible vegetable oils.

Arabica coffees contain 11.1 to 13.6% oil, whereas Robusta coffees contain only 4.4 to 4.8% oil. Apparently, there is even an increase of up to 20 percent in their levels in the roasted coffee. Triglycerides account for 70-80 percent of coffee oil’s content.

The relatively large unsaponifiable fraction is rich in diterpenes of the kaurane family, mainly cafestol, kahweol and 16.0 methylcafestol, which have received increasing attention in recent years because of their physiological effects.

For most part, the fatty acids are present as glycerol esters in the triglycerides, some 20% are esterified with diterpenes and a small proportion as sterol esters.
Triglycerides in coffee