Annealing improves the concentration and controlled release of encapsulated ethylene in V-type starch.

Ethylene gas was introduced into annealed V-type crystalline starches (V-starches). The morphological and structural properties of the inclusion complexes (ICs) were characterized using scanning electron microscopy, light microscopy, X-ray diffractometry, and 13C solid-state nuclear magnetic resonance spectroscopy. The ethylene concentration in ICs annealed at 70 °C and 50% (v/v) ethanol increased from 8.0-31.8% (w/w) to 18.1-49.6% (w/w). The controlled release characteristics of ICs were also investigated under various temperature and relative humidity conditions by fitting to the Avrami equation. ICs prepared with annealed V-starches were more stable in different storage environments, which may be due to well-formed helices with higher crystallinity and larger crystallite size. Thus, annealing is an important heat treatment technique with potential for material modification.