Optimización de tostado y cinética de granos de café pretratados con caída de presión cruda e instantánea

Resumen

Introduction: Coffee is one of the most widely consumed beverages in the world. The desired aroma and flavour of coffee are developed during
roasting which is the most important step in coffee processing. Instant Controlled Pressure Drop Process (DIC) technology is controlled high
temperature and short time process which been used successfully to improving the kinetics of drying, extraction, and decontamination of fresh and dried natural products. The main advantages of DIC are that it is a master controlled temperature and time process, the dwell times are short, reducing the chemical degradation, so new products with superior quality attributes may be developed. Materials and Methods: Two coffee beans varieties were investigated by Brazilian and Ethiopian sources. The raw beans were pre-treated using the DIC process under adopted conditions prior to roasting. A two-factor central composite design was used to optimize the settings of roasting time and roasting temperature on response variables of bulk, true and normalized density, and roasting degree. Also, microscopic analysis using Scanning Electron Microscopy (SEM) and kinetics of the roasting processes are included. Results and Discussion: The obtained results confirmed that the roasted DIC treated beans for both varieties have lower densities, higher roasting degree and lower activation energy needed for roasting compared to the raw beans. The physical properties’ magnitude is highly relevant to coffee origin. Roasting time and the temperature seemed to be of significant regarding all the physical characteristics of the beans, however, time was of topmost significance. Besides, treating coffee been by DIC prior to roasting leads to texture modification and conservation of time and energy needed for roasting. Conclusions: The physical properties of the roasted coffee beans are highly affected and changed with the coffee origin, roasting conditions and pre-treatment of coffee beans prior to roasting using the DIC process. The incorporation of the DIC process prior to roasting seemed to achieve more conservation of time and energy needed for roasting compared to the raw untreated beans. The higher degree of roasting and the competitive roasting activation energy of Brazilian coffee beans give a
conclusion that more economic roasting process could be achieved with the Brazilian coffee. The pre-treatment by DIC enhances the remarkable reduction in coffee beans density and increasing in the roasting degrees that are in line with the industrial needs of coffee beverages. Response Surface Methodology is an efficient tool for optimization and mathematical modeling of the coffee roasting process.