Rapid approach to identify the presence of Arabica and Robusta species in coffee using 1H NMR spectroscopy. (1st September 2015) - Monakhova, Yulia B.
Graphical abstract: Highlights: Lipophilic extracts of 101 coffee samples were investigated using NMR. The classic markers 16-OMC (Robusta) and kahweol (Arabica) can be used for coffee species assignment. The 16-OMC signal ( δ 3.165 ppm) can also be used to estimate the Robusta amount in coffee blends (LOD 1–3%). Non-targeted approaches confirmed the univariate findings. Abstract: NMR spectroscopy was used to verify the presence of Arabica and Robusta species in coffee. Lipophilic extracts of authentic roasted and green coffees showed the presence of established markers for Robusta (16- O -methylcafestol (16-OMC)) and for Arabica (kahweol). The integration of the 16-OMC signal ( δ 3.165 ppm) was used to estimate the amount of Robusta in coffee blends with an approximate limit of detection of 1–3%. The method was successfully applied for the analysis of 77 commercial coffee samples (coffee pods, coffee capsules, and coffee beans). Furthermore, principal component analysis (PCA) was applied to the spectra of lipophilic and aqueous extracts of 20 monovarietal authentic samples. Clusters of the two species were observed. NMR spectroscopy can be used as a rapid prescreening tool to discriminate Arabica and Robusta coffee species before the confirmation applying the official method.