Quality study on different parts of Panax notoginseng root drying with a hybrid drying system powered by a solar photovoltaic/thermal air collector and wind turbine

Abstract

In order to improve the utilization rate of renewable energy in the drying system and further solve the problem of insufficient solar energy supply, a novel hybrid drying system powered by a solar photovoltaic/thermal air collector and wind turbine was proposed. The heat energy and electricity required for drying process are provided entirely by solar energy and wind energy. In this paper, the drying kinetics, colour parameters, microstructure, thermal stability and ginsenoside contents of different parts of Panax notoginseng dried using the drying system and open sun were studied. Additionally, the economic analysis on the drying system was also conducted on. The drying time using the dryer to dry the main root slices was shortened by 33.3% compared with natural sun drying when the moisture content decreased from the initial value to 13%. For rhizome and fibrous roots, the drying time was shortened by 74.1% and 53.8%, respectively, when the moisture content was decreased to approximately 15% and 12%. Meanwhile, the total saponin contents of the main root slices and rhizome in the dryer were higher, exhibiting average values of 9.1% and 12.2%, respectively. Thus, the drying system is suitable for drying Panax notoginseng, and the payback period was approximately 1.03 year.