The Limited Oxygen lot is a natural-processed coffee — but with an extended, sealed fermentation phase added into the mix. To start, the coffee dropped off at the mill is poured into a tank of water, so high quality cherry can be separated. Then, instead of heading straight to drying tables, these batches of sorted coffee cherries are packed in hermetically sealed bags and set in the shade. This creates a low-oxygen or semi-anaerobic environment for the coffee to start slowly fermenting in. After 16-24 hours sealed, the batches are unbagged and laid on nylon mesh tables to dry in the sun for +15 days, until the cherry is ready to be milled off and the coffee is stored away to be shipped.

600 independent growers trade their cherry at the Dumerso Mill, and over 400 people are employed there during harvest. It’s owned and run by two sisters, Hirut Berhanu and Mahder Birhanu. Hirut bought the mill in 2010, and has overcome significant obstacles to get the mill to what it is today - the entire mill was destroyed during a wave of geographic/culturally motivated attacks in 2017. Today, the site continues to flourish as a leader in Gedeo's agriculture community.