Performance evaluation of an automated hybrid solar system dryer for drying some aromatic herbs

Abstract

The hybrid solar smart dryer (HSSD) was established to dry medicinal and aromatic herbs that are sensitive to direct sunlight. This study explores the effectiveness of the HSSD as an indirect solar drying technique in drying lemongrass, thyme, marjoram, and lavender at different temperatures (30, 40, and 50 ± 2 °C), focusing on its ability to retain quality features. The total energy consumption was estimated by values of 27.72 kWh for lemongrass and 43.02 kWh for lavender using HSSD at 50 ± 2 °C. Generally, HSSD showed an improvement in the studied physicochemical quality parameters. The green color retention was with the parameters of 15.60 ± 0.89, −5.28 ± 1.92, −3.89 ± 1.86, and −5.89 ± 2.40 for lemongrass, thyme, marjoram, and lavender samples, respectively. The highest values of the lemon grass, thyme, marjoram, and lavender oil content (1.96, 1.73, 3.40, and 2.76%, respectively) were obtained when the aromatic herbs were dried using the HSSD at 40 °C. This study showcased the effectiveness of solar dryers in preserving the physicochemical properties of lemongrass, thyme, marjoram, and lavender during drying, which could be applied to other food products. HSSD is a promising energy-efficient method that can save 19–36% of energy consumption, reducing the carbon footprint of drying processes and delivering high-quality products.