Rolling deformation characteristics of Chinese eaglewood leaf during drying and rehydration

Abstract

This study involves the rolling and unrolling phenomena of Chinese eaglewood leaves during drying and rehydration processes. In the early period of drying, eaglewood leaf rolls slightly and has a low leaf rolling index (LRI), i.e., <0.05, with decreasing leaf moisture content. Once moisture content declines to a critical value (Mc), the drying process enters into a fast rolling stage until LRI eventually reaches a drying equilibrium (LRIe). The leaf will then unroll upon rehydration; however, LRI cannot return to its initial value before drying and it will remain at a rehydrating equilibrium (RLRIe). Mc increases with increasing drying temperature and is hardly influenced by ambient air humidity, leaf size, and forced initial LRI. LRIe increases with increasing drying temperature, leaf size, forced LRI, and decreasing ambient air humidity. Meanwhile, RLRIe decreases as rehydration water temperature increases.