Thermal analysis of coffee beans of castilla variety grown in Colombia

Abstract

This article presents the main results achieved after thermally characterizing the coffee beans of the Castilla variety. Such beans were produced in the Southeastern region of Santander, Colombia. Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) tests were carried out.We determined various stages of thermal degradation within the beans, along with their thermal transitions. We also determined the variation of heat capacity throughout the process. Thermal characterization allowed us to carry out an analysis of the resulting gases, using infrared (IR) spectroscopy. We check the resulting experimental data against the Bruker IR database and we were able to detect three sectors within the coffee bean that exhibited a loss of mass, for a heating rate of 5 °C/min, and for temperatures up to 1000 °C. The zones were in the following regions: 58.5 °C and 324 °C, with a mass loss of 50.26%; 324 °C and 432 °C, with a mass loss of 14.67%; and 432 °C and 513 °C, with a mass loss of 4.46%. Residual mass was 24.11%. We obtain similar data with tests at a rate of 10 °C/min. The experiments suggest that temperatures below 60 °C are adequate for grain drying, and that the temperature range between 216 °C and 254 °C is interesting for roasting. The results offer important information about the specific thermic properties of the Castilla variety coffee beans, which until now has not been referenced in the literature consulted.