Abstract:
In Kenya, some coffee processing factories lack sufficient capacity to process coffee cherries
immediately after harvest, especially during the peak season. Such processing delays lead to
undesirable fermentation of coffee cherries that may affect the quality of the coffee. To mitigate
this problem, soaking of coffee cherries may be adopted in an attempt to preserve the cherries but
information on the effects of this practice on chemical composition of green coffee beans and
subsequently sensory quality is limited. Therefore, this study aimed at determining the effect of
soaking coffee cherries on the chemical composition of green coffee and cup quality of coffee
from Ruiru 11 cultivar cherries. Treated samples included coffee cherries soaked for a period of
seven and ten days with either daily change of soaking water or without change of soaking water.
The control composed of freshly processed coffee cherries. After soaking, the coffee cherries were
subjected to wet processing followed by sun drying. The green coffee beans were analyzed to
determine the moisture content, fats and crude ash by standard methods. Caffeine, chlorogenic
acids, sugars and trigonelline were determined using High Performance Liquid Chromatography.
The cup quality was determined by the use of three trained coffee cuppers. Soaking of coffee
cherries had a significant effect on the percentage crude fat (p :'.S 0.05) whereby the coffee samples
soaked for 7 days with daily change of water revealed higher percentage of crude fat of 15.23% as
compared to that soaked for 10 days without change of water with 15.12%. However, soaking did
not have any significant effect on the levels of trigonelline, chlorogenic acids, caffeine, sucrose,
calcium, potassium, magnesium and phosphorus. Sensory analysis revealed significant variations
(p :'.S 0.05) in terms ofraw bean color (2.67), flavor (4.78) and class (4+) of the coffee brew for the
freshly processed coffee cherries with the cup from the freshly processed coffee cherries giving
the best results. Discrimination function analysis placed the freshly processed coffee cherries
further distinctively from other soaked coffee cherries signifying better quality. In conclusion,
coffee from freshly harvested coffee cherries was of better quality than that from soaked cherries.
Therefore, soaking of coffee cherries by coffee processors is not a good practice.
