Influence of the intermittent drying on coffee

Experiments were carried out in 1953, 1956 and 1961 to determine the influence of the intermittent process for drying coffee. In 1956 the Bourbon Vermelho variety was used and the experiment was done in two parts: the first one, in short time intervals, with periods of drying and rest of 1/2 x 1 hour, 1/2 x 2 hours, 1x2 hours, 1x4 hours and continuous drying at 45°C, 60ºC and 75°C, using pulped cherries; the second one, in long time intervals, with periods of drying and rest of 2 x 10 hours, 4 x 10 hours and continuous drying just at 65°C using pulped cherries, unpulped cherries and coffee obtained from the usual «stripping» harvesting method. In 1961 a new experiment was performed using pulped and unpulped cherries from the Mundo Novo variety with drying periods of 1, 2, 3 and 4 hours until cooling to about 30ºC, and continuous drying. The test result did not show any statistical differences among the treatments. So, all the data together gave us the following information: a) the «parcelled» process for drying coffee reduces the total period of time and this effect is bigger for the umpulped cherries; b) in the intermittent drying process the Iowe the temperature the bigger will be the reduction of total period of drying; c) the bigger the number of «parcels» the greater the reduction of total time of drying; d) when the rest periods are large, for the same «parcels», the total time of drying is shorter; e) the intermittent drying process permits the increasing of yielding and capacity of the dryer; f) the excess of «parcels» is not recommended because it is laborious and not practical.