Green bean biochemical attributes of Arabusta coffee hybrids from Kenya using HPLC and soxhlet extraction methods

Robusta coffee yields higher than Arabica coffee. However, it is limited by the inferior cup quality. The biochemical compounds found in coffee interact and determines the final cup quality. The objective of the study was to characterize the biochemical compounds found in Arabusta coffee hybrids. Twenty coffee genotypes including the Arabusta hybrids, backcrosses, Robusta and Arabica coffee were established at KALRO-Alupe (Busia) and Siaya -ATC in the year 2015. Coffee cherry was harvested and processed in the year 2018 and the green beans were analysed for sucrose, oil, trigonelline, caffeine and chlorogenic acids using the HPLC and soxhlet method. There were significant differences amongst the genotypes for these biochemical compounds across the two different environments (Busia and Siaya counties). Robusta recorded higher levels of caffeine and chlorogenic acids while the Arabusta hybrids recorded intermediate levels of the biochemical compounds between the Robusta and Arabica coffee species. The Genotype by Environment (G x E) interaction effect was only significant for chlorogenic acids. Caffeine, sucrose, oil and trigonelline levels were significantly high for genotypes evaluated in Siaya when compared to Busia. Chlorogenic acid had a positive significant association with caffeine, but was negatively correlated with coffee oil and sucrose. Coffee oil indicated a positive significant association with sucrose and Trigonelline. The Principal Component Analysis (PCA) differentiated the genotypes based on the levels of biochemical compounds indicating high genetic variation amongst the genotypes. Arabusta hybrids exceeded Robusta coffee in performance of biochemical compounds which implies that there was a successful introgression of quality genes