Abstract:
In this study, the influence of altitude on caffeine, chlorogenic and nicotinic acid contents in coffee beans of some Arabica varieties grown in Southwest Ethiopia was investigated. Highperformance liquid chromatography with diode array detector was used for the simultaneous determinations of the target analytes. Totally, 12 coffee samples were collected from 4 coffee varieties cultivatedin high, mid and low altitudes. The moister content was ranged from (10.13 ± 0.04 to 12.49 ± 0.08) and the pH also ranges (5.36 ± 0.03 to 5.81 ± 0.04). The results of the chemical analysis showed that caffeine content in green coffee varieties was ranged from (12.34 ± 0.076 to 19.89 ± 0.288) mg/g, chlorogenic content was also recorded (27.17 ± 0.382 to 39.18 ± 0.24 ) mg/g and nicotinic acid was ranged from(7.13± 0.528 to 10.16 ± 0.75) mg/g. The caffeine content in roasted coffee varieties was ranged from ( 13.93 ± 0.299 to 20.88 ± 0.141) mg/g and chlorogenic content was recorded (8.56 ± 0.021 to 16.21 ± 0.109 ) mg/g and nicotinic acid ranged from (8.76 ± 0.114 to 6.34 ± 0.031) mg/g. A highly significant decrement was observed in chlorogenic acid content after roasting, as altitude increases the caffeine and chlorogenic acid decreased. In contrary, nicotinic acid increase as altitude increase in green coffee varieties. Two way ANOVA showed the presence of significant interaction between altitude and coffee varieties on chemical constituents of coffee. The caffeine content in green beans was lower as compared to roasted beans; significant degradation of chlorogenic acid was observed after roasting coffee of the same variety.
