Post-harvesting of Solanum paniculatum L. leaves. Part I: Drying kinetics

ABSTRACT Solanum paniculatum L. (jurubeba) is among the numerous medicinal plants used by the Brazilian population, and the use of its leaves is quite popular, in the form of tea, as a remedy against hangovers after excessive consumption of alcohol and food, besides being used in the form of ointments as healing agent and also in the treatment of liver and digestive problems. Leaves of medicinal plants usually have a high moisture content, requiring its reduction by drying, so that the product can be stored safely until its processing. The objective of this study was to evaluate the drying kinetics of jurubeba leaves and to determine the effective diffusion coefficient and activation energy during drying. Jurubeba leaves were dried at different air temperatures (30, 40, 50, 60 and 70 °C) and speed (0.4 and 0.8 m s-1). The Midilli model satisfactorily fitted to the observed data of drying of jurubeba leaves for all air conditions. Increasing the drying air temperature and speed reduced the drying time and increased the effective diffusion coefficient. For the air temperature range from 40 to 70 °C, as the drying air speed increases, the activation energy for the drying of the jurubeba leaves is reduced.

摘要 圆锥茄（Solanum paniculatum L.，俗称jurubeba）是巴西民众广泛使用的药用植物之一，其叶片常以茶饮形式缓解过量饮酒与进食后的宿醉不适，亦可制成软膏用作愈合剂，还可用于治疗肝脏与消化系统疾病。药用植物叶片通常含水量较高，需通过干燥工序降低含水率，以确保产品可安全储存直至后续加工。本研究旨在探究圆锥茄叶片的干燥动力学特性，并测定干燥过程中的有效扩散系数与活化能。本研究分别在不同空气温度（30、40、50、60、70 ℃）与风速（0.4、0.8 m·s⁻¹）条件下对圆锥茄叶片开展干燥实验。Midilli模型可良好拟合所有空气工况下的圆锥茄叶片干燥实测数据。提升干燥空气的温度与风速可缩短干燥时长，并提高有效扩散系数。在40 ℃至70 ℃的温度区间内，随着干燥风速升高，圆锥茄叶片干燥过程的活化能会降低。