Determinação dos parâmetros para a secagem em camada de espuma (foam-mat drying) das folhas da arruda (Ruta graveolens L.)

Abstract

Brazil is a country in which the use of medicinal plants to cure diseases is cultural and transmitted from generation to generation. The arruda is a medicinal plant that is present in several regions of Brazil and that has several proven biological activities such as: antitumor, antifungal, anti-inflammatory among others. For the use of the plant in the pharmaceutical industry it is important that a treatment is performed with the purpose of increasing the useful life of the plant, preserving its biological properties. Drying is an operation that is usually used to preserve food and medicinal products and acts by reducing the water activity of the material, thus preventing microbial growth. The dehydration in foam-mat can be used for juices and even purees, in general it is more efficient than the conventional drying, considering that the pores present in the foam facilitate the transfer of heat and mass, drying the material in less time. Thus, the present study investigated the best conditions for drying the arruda leaves in a foam-mat, considering that there is scarcity of information on the subject in the literature. For this study, the arruda leaves was used and the emulsifiers Emustab®, Portogel® and juá powder were tested to define the concentrations and agitation times for foam formation. Physical (density; percentages of expansion and incorporation of air and stability) and physical-chemical (pH and acidity) analyses were made for the foam formed. Portogel® was defined as the best foaming agent and the operational range for foam-mat drying was defined for the three variables: foaming concentration (2%, 4% and 6% in relation to the mass of juice or 8%, 10% and 12% in relation to the mass of leaves); mixing time (3 min, 5 min and 7 min) and temperature (50 ºC, 60 °C and 70 ºC). The formed foams presented a significant reduction in density, reaching 91.02% (exp. 7) in relation to the juice and satisfactory stabilities with a drained maximum volume of 6.5 mL (exp. 1). There were no significant variations in pH and acidity between juice and foams.