Dewatering And Drying Characteristics Of Coffee Pulp. I: Dewatering Characteristics. Kenya Coffee

Abstract

Coffee pulp is a by-product of wet coffee processing and can be used in various ways. However, the high moisture content of fresh coffee pulp is the major constraint in its utilization and needs to be lowered to 15 percent wet basis (wb) to ease its handling, transportation processing, and storage. This can be achieved by a two stage process comprising mechanical dewatering and drying of which the former is the subject of this paper. The dewatering process was investigated by subjecting coffee pulp samples to consolidated drained (CD) triaxial compression tests. Applied pressure and pressing duration were identified as the most important factors to the dewatering process. The relationship between expressed fluid and increasing pressure was exponential. A similar relationship was derived between the expressed fluid and pressing duration at a constant pressure. Empirical equations were developed for both conditions of varying and constant pressure. However, one of the coefficients varied significantly under varying pressure conditions for coffee pulp produced at different times of the picking season. This implied that there is need to study the biological properties of coffee pulp in order to make these coeficients and hence the equations reproducible during the design of a dewatering equipment.