Coffee Diterpenes: from Coffee Beans to Espresso Coffee.

The most important coffee diterpenes are kahweol, cafestol and 16-O-methylcafestol (16-OMC). These compounds are mostly esterified with various fatty acids and only a small amount is present in the free form. In addition to both minor diterpenes (e.g., 16-O-methylkahweol) and degradation products (e.g., dehydrocafestol, dehydrokahweol, kahweal and cafestal) they are important constituents of the unsaponifiable fraction of coffee oil. Both desirable and undesirable -biological activities have been ascribed to these compounds. In addition to anticarcinogenic, antioxidant, anti-inflammatory properties and hepatoprotective effects, a hypercolesterolemic activity (particularly for cafestol) has been reported. The interest towards coffee diterpenes is also triggered by their potential use as chemical markers for roasting intensity and for authentication purposes. Coffea arabica and Coffea canephora var. Robusta, the commercially exploited coffee species, differ not only in their agronomical performances, morphological characteristic, and organoleptic properties, but also in chemical composition, including diterpenes. Specifically, whereas cafestol is present in both species, kahweol is present in higher amount in C. arabica than Robusta and 16-OMC is present exclusively in Robusta, according to available literature. The quantitative determination of 16-OMC is routinely performed by the German standard method DIN 10779. The methodology is rather tedious, time- and solvent-consuming, but the separation of 16-OMC is quite good. The present work is aimed at characterizing diterpenes content in several coffee samples of both coffee species, from green beans to espresso coffee. Special focus has been placed on the determination of 16-OMC in the attempt to explore analytical methods alternative to the DIN standard that could guarantee the authenticity of 100% C. arabica blends by detecting possible commercial frauds in a rapid and reliable way.