Analysis of volatile compounds, α-dicarbonyl compounds, and acetic acid in Robusta coffee by soaking with D-xylose and D-ribose

The study investigated the impact of D-xylose and D-ribose soaking methods (autoclaved and non-autoclaved) on Robusta coffee's volatile compounds, α-dicarbonyl compounds (α-DCs), and acetic acid. Robusta coffees were soaked with D-xylose and D-ribose solutions, and the beans were dried until constant moisture content and lightly roasted. The sugar treatment led to an 85.6% reduction in pyrazine levels and a 64.4% decrease in pyridine, while pyrroles and furans increased significantly by 84.4% and 16.4%, respectively (p < 0.05). The total concentration of α-DCs was decreased by 24.6–69.2%, with the autoclaved D-xylose sample exhibiting the lowest among all samples. Acetic acid concentration was lower in non-autoclaved samples compared to autoclaved samples (p < 0.05). Principal component analysis indicated autoclave-treated pentose pretreatment reduced pyrazines and increased in the levels of 1-furfurylpyrrole, methyl furfuryl disulfide, 4-ethyl-2-methoxy-phenol, 2-methoxyphenol, 2-acetylpyrrole, pyridine, furfuryl acetate, and acetic acid. This study, utilizing GC–MS, GC–NPD, and HPLC–UV for compound quantification, offers valuable insights into the changes of volatiles, α-DCs, and acetic acid in Robusta coffee soaking with D-xylose and D-ribose, suggesting potential applications in the coffee industry to modulate flavor profiles.