Page optimization of the foam-mat drying process to soluble coffee production

Abstract The expansion of the soluble coffee production is an alternative to the traditional coffee consumption, which is necessary to meet the new demands of consumers looking for convenience and practicality. Thus, this study of techniques that simplify and reduce costs to obtain soluble coffee become even more pertinent. Therefore, the objective of this work was to optimize the drying process of coffee extract in the foam bed by adjusting the Page Model by non-linear regression. Two methods for the concentration of the extract were evaluated: (A) in rotary evaporator and (B) in open stainless-steel container. The kinetics of drying the coffee extract in a foam bed under the temperatures of 40, 50, 60, 70 and 80 °C were described by the model. Besides that, a multivariate equation was proposed for drying by detecting influence of temperature on the k parameter, of the Page Model and later validation of the results. The time to obtain the concentrated extract was close to the two concentration methods (A- 2 hours and 30 minutes and B- 2 hours and 40 minutes). The Page model presented a good fit with values of determination coefficients above 99%. The results confirmed that the temperature is a determinant factor in the product moisture loss speed, presenting shorter drying times with the temperature increase. The correlation between experimental and predicted data was satisfactory for the validation of the results. The mathematical model can also assist in the correlation of drying parameters with physicochemical and sensory changes of soluble coffee in order to improve technological parameters.