RESUMEN
The furan levels in commercial coffee product samples (17 instant coffees, 12 mixed coffee, 8 canned coffee) were 49-2155, 10-201 and 15-209 ng/g, respectively. Since thermal degradation/rearrangement of carbohydrates is the main source of furan, the concentrations of furan and monosaccharides (mannose, rhamnose, glucose, galactose and arabinose) were analysed in 26 green and roasted coffee bean (Coffea arabica) varieties. In coffee beans, furan levels ranged from 4.71 (Bourbon Cerrado, Brazil) to 8.63 mg/kg (San Vicente, Honduras). Galactose was the main monosaccharide in green beans, followed by arabinose, glucose, mannose and rhamnose, on average. Roasting decreased the glucose content by about 81%, and arabinose decreased about 27% in all coffee beans. Glucose decreased the greatest after roasting and is thereby considered the major contributor to the formation of furan.
RESUMEN
Coffee is a relevant source of dietary exposure for neoformed furan, alkyl furans and acrylamide. In this study, different statistical methods (hierarchical cluster analysis, correlation analysis, partial least squares regression analysis) were used for characterizing the formation of these process contaminants in green coffee beans roasted under the same standardized conditions. The results displayed a strong correlation between sucrose levels and furans in relation to the other sugars analyzed, while acrylamide formation was strongly related to the free asparagine. The data suggest that a sufficiently large amino acid pool in green coffee favors Maillard-induced acrylamide formation from asparagine, while reactions amongst the carbonyl-containing sugar fragmentation products leading to furan formation are suppressed. If the pool of free amino acids is small, it is depleted faster during roasting, thus favoring the formation of furans by caramelization, basically a sugar degradation process in which reactive carbonyl substances are generated and react together.