Addressing Potato Taste Defect in Coffee production in Rwanda


A sharp increase in the occurrence of potato taste disease in the 2013 Cup of Excellence called for a meeting of minds in Kigali in March.

Rwanda has made huge strides in improving post-harvest technology of Arabica coffee, producing one of the best Arabica specialties in the world. Within a decade, the number of primary processing units rose from 2 to 215 since the year 2000.  Despite these efforts, the potato taste defect has affected coffee beans, lowering the quality and income potential of otherwise exceptional coffee from coffee washing stations.

“Potato taste defect (PTD) remains one of the major impediments to marketing quality coffee from Great Lakes Region, Coffee buyers who spoke at the symposium said, “The random appearance of PTD in green coffee beans makes detection of affected beans a challenge, and makes it difficult to guarantee importers a defect-free product".

Assessment of occurrence of PTD in coffee lots entered into the Cup of Excellence Competitions revealed an increase of PTD occurrence by close to 51% in 2013 up from 18% in 2012. These results call for concerted efforts to alleviate the problem.

The genesis of PTD in coffee is still a mystery to coffee producers, consumers, and scientists. In some cases the issue has not been given sufficient importance due to lack of information about the causative agent, defect spread and incidence, and efficient detection methods, coupled with the random nature of occurrence. Various initiatives by academic and public institutions are underway to address the potato taste issues but the results are not yet conclusive and usable in controlling the problem.

The two-day symposium provided a platform for sharing experiences in research and extension activities on PTD and Integrated Pest management (IPM), and creating concerted, focused, and harmonized extension and research efforts to holistically address PTD in coffee. The participants came from University of Seattle, California, University of Rwanda, Research Institutes in East Africa Region, International NGOs and private sector.

Francois Sihimbiro represented SNV with a presentation that highlighted the best practices and technologies in the coffee washing stations in Rwanda and strategies developed so far to mitigate the potato taste defect. The symposium heard about techniques such as hand sorting, floating,  density sorting , electronic/optical sorting, final hand sorting and intensive cupping followed by  segregation of  different  lots  along with pesticide control of Antestia  bug at farm level; which have been useful in reducing the occurrence of PTD in coffee lots.  Unfortunately, the Potato Taste Defect has not been fully eradicated.

Further research, capacity building and information flow is hence needed at the whole chain for the PTD mitigation strategy to be effective. The International Coffee Research symposium was organized by Ministry of Agriculture and animal resources in partnership with University of Rwanda and Global knowledge initiative and brought together coffee development players, producers, buyers and researchers.