Aging must take place in a tropical environment, where beans take on moisture at the height of the monsoon season, and give it back during the drier season, without ever drying completely. This process deepens the flavor and makes it mellower, while accentuating certain taste components over others.

 

Coffee production in Sumatra began in the 18th century under colonial domination, introduced first to the northern region of Aceh around Lake Tawar Lake. Most coffee is produced around the Lake Toba region, in the subregions of Lintong Nihuta, Sumbul, and Takengon.

 

Sumatran coffee, though, is not usually sold by region. Unlike most coffees, Sumatra Mandheling is named after an ethnic group rather than a geographical region. The Mandheling are the ethnic group most often involved in coffee production in Sumatra.