Abstract:
In Kenya, coffee is an important export commodity and is the fourth leading foreign
exchange earner. The method used during coffee processing affects the final quality
produced. Processors undertake fermentation by employing different methods such as
using different containers with varying fermentation conditions that may consequently
affect the composition and quality characteristics of coffee. This research aimed at
determining the effect of different fermentation methods on chemical composition and the
sensory quality of coffee. Coffee cherries were pulped and subjected to dry fermentation
methods with the use of different containers; plastic bucket with perforations, sack and
cement tank with a drain. Wet fermentation was done in a plastic bucket and water was
added. After fermentation, the parchment were washed and dried. The green coffee beans
obtained were evaluated for proximate composition, titratable acidity, pH, sucrose,
caffeine, chlorogenic acids and trigonelline. The green coffee beans were roasted, ground,
brewed and analyzed for sensory attributes by a panel of professional cuppers. The results
showed that different fermentation methods did not have significant variations in most of
the physico-chemical parameters analyzed. The crude protein content of the green beans
ranged from l 0.62- I 0.82% for all the samples while sucrose levels were in the range of
7.76- 8.03% for all the samples. The pH levels varied from 6.00- 6.06. There were
significant variations were observed in the levels of pH with the wet fermented coffee
samples showing slightly lower levels as compared to dry fermented samples. Sensory
evaluation results showed that the wet fermented coffee samples had better color of green
beans, least silver skin discoloration and better overall quality compared to dry fermented
coffee samples in all treatments. Sensory analysis also showed that there were no
significant differences among the coffee samples that were dry fermented using different
containers and the convectional cement tank considering color, flavor and overall class
attributes. It was concluded that the use of other fermentation containers other than cement
tanks do not affect the quality of coffee produced. Hence different containers used during
fen~1entation do not ~ffect coffee quality and processors can adopt inexpensive J!-1
during coffee processing.
