Effect of coffee cherry maturity on the performance of the drying process of the bean: Sorption isotherms and dielectric spectroscopy

Abstract The study of the dynamic sorption isotherms of parchment coffee revealed that the maturity stage has an effect on the water availability of the bean, and that such dependence might affect the bean drying. The cultivar had an impact on the dispersion at high water activity values (aw > 0.8); hence, depicting dissimilar conditions before the drying is actually performed. The Guggenheim-Anderson-de Boer (GAB) sorption model revealed that stages 2, 3 and 7 present higher monolayer moisture content (Xm), K values close to one for all stages indicated a multilayer behaviour close to free water mobility and low C values for stages 2 and 7 represented a stronger water binding to the monolayer for these stages. Under static conditions and the drying conditions defined according to the moisture content of the beans, the unripe stages depicted an accelerated water activity decay that might promote stalling after roasting due to low values of the attribute (aw