Standards Development

Scope

This document specifies an HPLC method for determining the 16-OMC content in green and roasted coffee. The method described is suitable for a mass fraction of 20 mg to 1600 mg of 16- O-methylcafestol per kg of green and roasted coffee respectively.

Purpose

Of all the species of coffee there are two that have acquired worldwide economic importance: Coffea Arabica and Coffea canephora var. Robusta. The Arabicas are valued much more highly by the trade due to a far more pronounced and above all finer flavour than the Robustas. This is why they are the first choice of many consumers. In many cases, Arabica and Robusta species are easy to distinguish by the size of the beans. This visible criterion, however, is eliminated by roasting and consequent grinding.

It is possible to detect quantities over 15% of Robusta coffee in Arabica blends by sensory testing, but such results are based only on a subjective impression. Therefore, efforts have been made to characterize the two coffee species in an objective manner using chemical-analytical data.

The diterpene 16-O-methylcafestol (16-OMC) allows for such objective evidence; whilst the component was detected in all the green Robusta coffees analyzed, it could not or at most sporadically be detected in traces of up to 20 mg in any of the green Arabica coffees by using the analytical method. Due to its stability during roasting, the diterpene 16-OMC is the ideal quality characteristic for reliably detecting the addition of Robusta to Arabica coffee.