Rapid Authentication of Coffee Blends and Quantification of 16-O-Methylcafestol in Roasted Coffee Beans by NMR
Journal of agricultural and food chemistry | 29 Nov 2014
E Schievano, C Finotello, E De Angelis, S Mammi and L Navarini
Roasted coffee is subject to commercial frauds because the high-quality Coffea arabica species, described as “100% Arabica” or “Highland coffee”, is often mixed with the less expensive Coffea canephora var. Robusta. The quantification of 16-O-methylcafestol (16-OMC) is useful to monitor the authenticity of the products as well as the Robusta content in blends. The German standard method DIN 10779 is used in the determination of 16-OMC in roasted coffee beans to detect C. canephora in blends, but it is laborious and time consuming. Here, we introduce a new method that provides a quantitative determination of esterified 16-OMC directly in coffee extracts by means of high-resolution 1H-NMR spectroscopy. LoD and LoQ were 5 mg/kg and 20 mg/kg, respectively, which are adequate to detect the presence of Robusta at percentages lower than 0.9%. The proposed method is much faster, more sensitive, and much more reproducible than the DIN standard method.
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