Chlorogenic acid and caffeine are among the important components in coffee beans, determining the taste and aroma. In addition, phenols and antioxidants content possess vital health values. The main aim of this study is to determine the levels of caffeine and chlorogenic acid in several coffee samples of different origins and degrees of roasting. The coffee samples were extracted using hot water. The levels of caffeine and chlorogenic acid were quantified using high-performance liquid chromatography (HPLC) equipped with a diode array detector, a reverse phase system, and an ODS column (C18). Total phenol and antioxidant contents were previously determined for the same samples. The results showed that the highest content of caffeine was found in the medium roasted coffee (203.63 mg/L), and the highest content of chlorogenic acid content was found in the green coffee (543.23 mg/L). The results demonstrated a negative correlation between the chlorogenic acid levels with the degree of roasting, while it showed a positive correlation between the caffeine levels with the degree of roasting till a certain point where the levels dropped in the dark roasted coffee. The origin of coffee samples did not show any effect on any of the measured variables. Antioxidant effects of coffee samples were largely determined by chlorogenic acid content.

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The aim of this study is to compare the elemental composition among different coffee varieties consumed in Jordan. Levels of different metallic elements in coffee samples; green and roasted coffee beans from five origins; Brazil, Ethiopia, Kenya, Columbia, and India, collected from the Jordanian market were investigated. Twenty-two elements, including essential and toxic elements such as potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), aluminum (Al), manganese (Mn), copper (Cu), barium (Ba), strontium (Sr), zinc (Zn), chromium (Cr), lead (Pb), nickel (Ni), vanadium (V), cobalt (Co), gallium (Ga), uranium (U), cadmium (Cd), silver (Ag), lithium (Li), indium (In), bismuth (Bi), thorium (Th), and thallium (Ti), were determined using inductively coupled plasma-mass spectrometry (ICP-MS). The detected heavy metals and their intake per 1 cup of coffee did not largely contribute to the recommended daily intake (RDI) and tolerable upper limit of daily intake (TULD) in an adult with an average body weight of 80 kg. The ICP-MS versus flame atomic absorption spectrometry (FAAS) results were linearly fitted, and the correlation coefficients ( R2 > 0.95) were better than 0.95 for the three checked elements. No significant difference between the results of the two techniques was observed ( p > 0.05). The ANOVA results indicated the presence of a significant difference between the levels of Cr, Co, and Zn in green and roasted coffee beans. The results of this study indicated that the coffee consumed in Jordan did not contain toxic levels of heavy elements and is safe for consumption according to health organizations.

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This work was carried out in collaboration between all authors. Author WHT designed the study, performed the statistical analysis, wrote the protocol, and wrote the first draft of the manuscript. Authors RAI and FK managed the phytochemical analyses of the study. Author AMM contributed to the study design, the analysis of the results, and the technical support.All authors read and approved the final manuscript.