The variation of caffeine, chlorogenic acids, and nicotinic acid content and the physical attributes of forest coffees along a transect of the Kafa Biosphere Reserve

The study examined the physical and chemical characteristics of Kafa Biosphere Reserve Forest coffees, collecting 54 georeferenced samples from various zones and plots within the forests. Samples were processed, cleaned, and ground, and chemical contents were determined using high-performance liquid chromatography. Analysis of variance, descriptive statistics, principal component, multiple factors, and hierarchical cluster analysis were applied to the data collected in a three-stage balanced nested design. The district difference did not significantly affect bean physical and chemical contents, but it did affect fruit physical qualities. Forest zonation did not affect these attributes. The effect of forest plotting was significant on the chlorogenic acid content, fruit width and thickness, and seed length. The descriptive statistics results revealed significant variations in coffee chemical compounds across different sampling locations. The principal component analysis revealed that 61.97% of variation in forest coffee chemical and physical attributes is influenced by factors like chlorogenic acid content and fruit and seed width. Multiple-factor analysis showed a tendency for a relationship to be observed between the elevation gradient with nicotinic acid and the measured physical attributes of coffee samples. Nicotinic acid tends to increase with elevation, whereas coffee fruit and seed sizes become larger with reduced nicotinic acid content at a decreasing elevation. Cluster analysis categorizes the samples into three major clusters. The study confirms that the chemical and physical properties of coffee fruit and beans vary more significantly in smaller sampling categories, suggesting further investigation.