title: Rapid authentication of coffee blends and quantification of 16-O-methylcafestol in roasted coffee beans by nuclear magnetic resonance.
abstract: 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 proton nuclear magnetic resonance spectroscopy. Limit of detection and limit of quantitation were 5 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.
authors.affiliation: Department of Chemical Sciences, University of Padova , via Marzolo 1, 35131 Padova, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Schievano
authors.forename: Claudia
authors.initials: C
authors.lastname: Finotello
authors.forename: Elisabetta
authors.initials: E
authors.lastname: De Angelis
authors.forename: Stefano
authors.initials: S
authors.lastname: Mammi
authors.forename: Luciano
authors.initials: L
authors.lastname: Navarini
mesh_terms: D040503:Coffea / Q000737:chemistry*; D003069:Coffee / Q000737:chemistry*; D003296:Cooking; D004224:Diterpenes / Q000032:analysis*; D005506:Food Contamination / Q000032:analysis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010936:Plant Extracts / Q000032:analysis*; D012639:Seeds / Q000737:chemistry*
chemical_list: C000600293:16-O-methylcafestol; D003069:Coffee; D004224:Diterpenes; D010936:Plant Extracts
keywords: 16-O-methylcafestol; Coffea canephora var. Robusta; coffee blends; food control; qHNMR