Khater El-Sayed G, Bahnasawy Adel H, Oraiath Awad Ali Tayoush, Elwakeel Abdallah Elshawadfy, Elbeltagi Ahmed, Salem Ali, Dewidar Ahmed Z, Okasha Abdelaziz M, Metwally Khaled A
Agricultural and Biosystems Engineering Department, Faculty of Agriculture, Benha University, P.O. Box 13736, Moshtohor, Toukh, Kalubia, Egypt.
Department of Agricultural Engineering, Faculty of Agriculture, Omar Al Mukhtar University, P.O. Box 991, Al Bayda, Libya.
Sci Rep. 2025 Aug 19;15(1):30368. doi: 10.1038/s41598-025-14663-z.
Egyptian sweet marjoram leaves (ESML) are aromatic herbs long valued for their ability to enhance flavor and extend shelf life by inhibiting the autoxidation of food lipids. Despite their widespread use, limited research exists on how various drying techniques, air temperatures, and thin-layer thicknesses affect the drying behavior, mathematical modeling, effective moisture diffusivity (EMD), activation energy, and thermodynamic properties of ESML. This study addresses this gap by examining the drying characteristics of ESML using a hybrid solar drying system (HSDS) at three air temperatures (50, 60, and 70 °C) and three layer thicknesses (1, 2, and 3 cm), comparing with a conventional oven drying (OD). The findings revealed that HSDS at 70 °C with a 3 cm layer thickness achieved the highest equilibrium moisture content (EMC), while HSDS at the same temperature with a 1 cm layer thickness resulted in the shortest drying time, highest drying rate, and moisture ratio. Additionally, the highest activation energy was observed using HSDS at 70 °C and a 2 cm layer thickness. Notably, drying at 70 °C with a 1 cm layer thickness reduced drying time by 66.67% compared to drying at 50 °C for the same thickness. Nonlinear regression analysis of eleven thin-layer drying models identified Weibullian (I) and Midilli as the best-fitting models for HSDS and OD, respectively. The HSDS demonstrated comparable performance to the OD while utilizing solar energy as a renewable heat. These findings advance the knowledge of drying systems by demonstrating the effectiveness and sustainability of hybrid solar drying for preserving the quality and functional properties of medicinal and aromatic herbs like marjoram.
埃及甜马郁兰叶（ESML）是一种芳香草本植物，长期以来因其能够通过抑制食品脂质的自动氧化来增强风味和延长保质期而受到重视。尽管它们被广泛使用，但关于各种干燥技术、空气温度和薄层厚度如何影响ESML的干燥行为、数学建模、有效水分扩散率（EMD）、活化能和热力学性质的研究却很有限。本研究通过使用混合太阳能干燥系统（HSDS）在三种空气温度（50、60和70°C）和三种层厚度（1、2和3厘米）下研究ESML的干燥特性来填补这一空白，并与传统烘箱干燥（OD）进行比较。研究结果表明，70°C、3厘米层厚度的HSDS达到了最高的平衡水分含量（EMC），而相同温度、1厘米层厚度的HSDS干燥时间最短、干燥速率最高且水分比最高。此外，在70°C、2厘米层厚度的HSDS中观察到了最高的活化能。值得注意的是，与相同厚度在50°C下干燥相比，70°C、1厘米层厚度干燥可使干燥时间减少66.67%。对11种薄层干燥模型的非线性回归分析确定，威布尔（I）模型和米迪利模型分别是HSDS和OD的最佳拟合模型。HSDS在利用太阳能作为可再生热源的同时，表现出与OD相当的性能。这些发现通过证明混合太阳能干燥在保存马郁兰等药用和芳香草本植物的质量和功能特性方面的有效性和可持续性，推进了对干燥系统的认识。
