Many of us use the term “coffee oils” or refer to them every day. Occaisonally visible after roasting, the shining glaze of a dark roast is something that sticks in the general public’s mind.
In this series of articles I am going to delve into these oils and hopefully explain them a little more, as well as look at them through coffee history. I will amend and update them as I find new information…
Research and Discovery of Coffee Oils
The chemical research going on in coffee doesn’t really apply to the oils until 1880, when a gentleman named Bernheimer publishes a paper entitled “Zur Kenntnis der Rostproducte des Caffees”. As part of a series of distillation experiments he found, at 300C, a fatty mass start to distil, with the consistency of butter, and the odour of rancid fat. He called it “caffeol”. He did not by any means discover the oils in coffee, fats being estimated as constituting 10-13% in a papers published by Payen in the late 1840s. Also in 1880 Cech published a paper on the preparation of coffee oils, though it was short and unsubstantial. For the next 20 years the entire complex mixture of organic compounds produced by decomposition of larger molecules was considered to be this “caffeol”.
In 1902 Erdmann publishes a paper that not only picks apart previous theories, changes the name caffeol to kaffeol, but also contains empirical discoveries concerning browning reactions between sugars and amino acids that would be the subject of a paper by Maillard ten years later, and would come to bear his name.
By 1912 confusing nomenclature means that “Kaffeol”. “Kaffeon”, “Caféone” and “Kaffeeöl” have all come to mean the group of aromatic substances obtained by water and ether distillations and research in coffee oil becomes the extension of research and discovery of new and important volatile aromatics.
Through the following part of the early 20th century fats in coffee are blamed and then exonerated for staling compounds due to fat rancidity. In the 50’s it is announced that fats don’t degrade in roasting, but still play a role adsorbing and protecting volatile aromas. After 1956 and the advent of Gas Chromatography (GC) and mass spectrometry (MS) the world of coffee researched changed completely and we leap forward to discuss what is actually in coffee oil….