In this study, the first-order derivative spectra technique was applied to determine the levels of caffeine and chlorogenic acids (CGA) in both defective (immature, black, and sour) and non-defective coffee beans, without the need for extraction procedures, background correction, or additional reagents. The extreme points in the first-order derivative spectra, observed at wavelengths of 260 nm and 292 nm, were used for the quantification of caffeine and chlorogenic acids, respectively.
The results of the study indicated that caffeine content in coffee beans ranged from 1.2 ± 0.12% to 1.46 ± 0.47%, while chlorogenic acids content ranged from 4.04 ± 0.44% to 4.43 ± 0.43%. Furthermore, the analysis revealed that the total levels of caffeine and chlorogenic acids could effectively discriminate between defective and non-defective coffee beans, with defective beans exhibiting higher concentrations of both compounds.
Given its rapidity, simplicity, and cost-effectiveness, as well as its minimal sample preparation requirements, this first-order derivative spectral method presents a valuable tool for the routine quality control and assessment of caffeine and chlorogenic acids content in coffee beans.