Secagem em camada de espuma de folhas de kalanchoe laetivirens: testes preliminares para definição de parâmetros

Abstract

Kalanchoe laetivirens, popularly known as aranto, has attracted scientific interest due to the presence of bioactive compounds associated with various pharmacological activities. However, the high moisture content of its leaves hinders preservation, making it necessary to apply processing techniques that enhance stability and facilitate its use. In this context, foam-mat drying stands out as an efficient alternative for dehydrating liquid or pasty plant materials, as it increases the contact surface area with the drying air, thereby reducing processing time. Thus, the aim of this study was to evaluate the feasibility of foam-mat drying of Kalanchoe laetivirens leaves, focusing on defining suitable parameters for foam formation and analyzing the influence of temperature on the drying process. Initially, experiments were carried out to characterize the foam by evaluating parameters such as density, expansion (overrun), and stability, using the foaming agent Emustab under different experimental conditions (variations in juice dilution, emulsifier concentration, and whipping time). Based on the results, experiment 7 was identified as the most suitable condition, corresponding to lower juice dilution, higher emulsifier concentration, and longer whipping time, which resulted in lower density, higher air incorporation, and greater foam stability. Subsequently, the foam obtained under the selected conditions was subjected to drying at different temperatures (50 °C, 60 °C, and 70 °C) in order to evaluate the influence of this variable on the material behavior during the process. The results indicated that 60 °C presented the best performance among the evaluated conditions, providing lower water activity, higher titratable acidity, and absence of significant structural changes, such as cracks in the dried layer, in addition to reduced indications of thermal degradation. Therefore, foam-mat drying proved to be a promising technique for dehydrating Kalanchoe laetivirens leaves, contributing to the production of a more stable powder with potential for future applications.