How moisture levels are measured (Coffee Processing)

    Ask any Salvadoran what the moisture percentage is within a coffee on the patio, and they’ll likely bend down, pick up a piece of parchment, and abruptly put it into their mouth, analyzing the softness of the bean with their teeth, in order to determine their perceived moisture of the coffee, and, if as experienced as ‘Benche,’ the patio manager here at El Manzano, are more often then not, spot on.

 

    In time however, science has caught up with tradition, and machines now are able to determine within seconds, the internal humidity or moisture of a coffee from the patios or mechanical dryer.    

    Moisture levels in a coffee can be measured in two ways; first, by analyzing the parchment (pergamino), or secondly, by analyzing the green coffee within the parchment (cafe oro). Both methods are performed by a machine, within the laboratory at Beneficio El Manzano.

    The machine used at the mill for measuring moisture is produced by Gehaka, a Brazilian company, specializing in the manufacturing of measuring equipment. Our machine is the G600 Moisture Tester. 

    In either process, 1000 gram samples of coffee are taken from either the patio, or from the mechanical dryer. Since coffee is dried in the parchment, it will arrive at the lab within the parchment. From this point, it can either be entered directly into the machine as parchment, or it can be hulled, stripped of the parchment, and analyzed as green coffee. 

    Measurements are more accurate, when taken from coffees within the green coffee state, therefore, most measurements taken from the patios or dryers, are performed in this state. 

    To measure, green coffee is poured into a cup on the back of the machine, which rests on a small metal piece, counterbalancing a level on the front of the machine. As the cup is being filled with coffee, the bar on which the cup is balancing will level out, indicating that the appropriate amount has been reached for the measurement. 

    Coffee is then poured into the machine, which reads the sample, and calculates the internal moisture, indicating the percentage on a screen. 

    Once the moisture content has been determined, the sample is brought back to either the patio or the dryer, at which point, depending on the moisture reading, coffees will proceed with drying/processing, (left for more time on the patio or dryer, or removed and bagged, to enter the warehouse).