Sorption Isotherms and Isosteric Heat of Pericarp and Endosperm Tissues of Arabica Coffee Fruit

Abstract

The aim of this study was to evaluate and model the hygroscopic equilibrium and isosteric heat curves of pericarp and endosperm tissues of arabica (Coffea arabica) coffee fruit, in different temperature and relative humidity conditions. Sorption isotherms were drawn under temperatures from 20°C to 70°C and relative humidity ranging between 10% and 90% until the product reached the equilibrium water content with the environment. The experiment was set up in a 4 × 4 factorial scheme (four relative humidity of the drying air and three tissues of the coffee cherry pericarp + endosperm [1: exocarp + part of the mesocarp, 2: mesocarp, 3: endocarp, 4: endosperm]), in a completely randomized design, with three repetitions. The results were examined by analysis of variance and regression using the STATISTICA 5.0 statistical software. Among the analyzed models, the ones that best fit the experimental data were modified GAB, for exocarp + part of mesocarp and mesocarp, modified Henderson, for endocarp, and Sabbab for endosperm. It was observed that, for all treatments, the lower water contents required a higher amount of energy to reach the equilibrium water content, and the integral isosteric heat decreased with the increasing equilibrium water content.

Mathematical modeling of dehydration resistance of pericarp tissues and endosperm in fruits of arabic coffee

“…Every year new technologies in the postharvest of coffee are brought to market, but the behavior of each intrinsic part of coffee during drying and how this interaction and interdependence occurs is not yet known. The resistance imposed by the pericarp and endosperm tissues that make up the coffee fruit increases the drying time and, consequently, the energy expenditure (Dias et al, 2020).…”

Improving the drying performance of parchment coffee due to the newly redesigned drying chamber

“…2.3.4 | Parchment coffee latent heat of vaporizationTrejos et al (1989) described the coffee parchment's latent heat of vaporization L as reads the Equation (10), where M should be considered in decimal notation (d.b). L was defined as a function of the latent heat of free water vaporization, verified byDias et al (2020) andCorrêa et al (2010) when attaining the coffee isotherms.…”