PARAFAC HPLC-DAD metabolomic fingerprint investigation of reference and crossed coffees

Abstract

In this study two cultivars of Coffea arabica L., Bourbon (reference) and IPR101 (crossing) were analyzed. The extracts were prepared according to a simplex centroid design with four components, ethanol, ethyl acetate, dichloromethane, and hexane. Multiway data were obtained by HPLC-DAD analysis of the fifteen different mixtures for each cultivar. The PARAFAC methodology was used to investigate the chromatographic fingerprint. For both cultivars, Factor 1 was able to discriminate mixtures containing ethyl acetate as solvent. Factor 2 indicated that mixtures in pure ethanol and binary mixtures containing ethanol were the most efficient in extracting chlorogenic acids and factor 3 identified methylxanthines through spectrophotometric profile in all mixtures. Higher concentrations were obtained by the ethanol, dichloromethane and hexane ternary mixture for the Bourbon cultivar and by the quaternary mixture of these solvents with ethyl acetate for the IPR101 cultivar. Trigonelline and cafestol were extracted in both cultivars. The reference coffee showed higher relative abundances of cafestol ester, chlorogenic acids and trigonelline whereas the crossed coffee showed higher levels of caffeine. To confirm these results, UPLC-MS was used as a complementary method to confirm the presence of the metabolites in these extracts. The three way PARAFAC strategy determines correlations of HPLC-DAD chromatographic and spectral data simultaneously with samples permitting a more unambiguous assignment of metabolic groups than can be obtained treating chromatographic and spectral data separately by two way methods. This can provide higher quality chromatographic fingerprints for food chemistry.