Recent advances in the drying of medicinal herb by novel physical field-based techniques: A review

Abstract

Fresh medicinal herbs are highly perishable and sensitive to chilling. Traditional drying techniques, such as hot air and solar drying, are well-established and widely adopted commercially. However, these methods involve long drying times, which can potentially lead to a decline in the quality of medicinal herbs, including discoloration, burning, or the loss of functional properties. As public awareness of health continues to grow and the concept of medicine and food homology gains increasing attention, the demand for high-quality dried medicinal herbs has been rising annually, prompting researchers to explore and develop novel drying technologies. This paper introduces a series of novel physical field-based drying (PFD) technologies, which involve electromagnetic, electric fields, and acoustic, as well as their combinations. These technologies are reviewed for possible opportunities to enhance the drying efficiency and improve the quality characteristics of medicinal herbs. The drying mechanism, major finds, typical equipment, as well as the characteristics of each technology are systematically reviewed. Furthermore, the challenges and future directions of PFD are also discussed to facilitate its better practical applications within the medicinal herb industry. This paper also presents specific theoretical insights and practical applications, aimed to enhance the design and scaling-up process of PFD technologies.