Encapsulation and release characteristics of ethylene gas from V6- and V7-type crystalline starches

Abstract Ethylene (ethene, C2H4) was introduced into V-type crystalline starches (V-starches, namely V6- and V7-types) with different single helix contents (8.35–35.54%) by a solid encapsulation method. The morphological and structural properties of V-starches and their inclusion complexes (ICs) were characterized. The V-starches prepared with n-propanol (1-propanol) and ethanol showed a V6-type crystalline structure, whereas V-starches prepared with isopropanol (2-propanol) and t-butanol (2-methyl-2-propanol) exhibited V7-type crystalline structure. The ethylene concentrations in ICs followed the order of Vn-propanol > Vethanol > Visopropanol > Vt-butanol > Vmethanol, which appeared to be associated with the diameter of the V-starch single helices. Compared with V7-type starches, ethylene was more effectively encapsulated into V6-type starches with a smaller inner diameter. The controlled-release characteristics of ICs showed a diffusion-limited mechanism and first-order kinetics for ICs in different temperatures and relative humidities, respectively. Ethylene encapsulated in V6-type-ICs showed better controlled release kinetics than V7-type-ICs, except for Vt-butanol-IC, which probably resulted from residual t-butanol in the single helices interfering with the release of ethylene. V-starches (particularly V6-type) appear to be effective gas storage and release systems for ethylene and this encapsulation technology should enable precisely-controlled and targeted applications of ethylene for food processing and agricultural applications.