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

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 V_n-propanol > V_ethanol > V_isopropanol > V_t-butanol > V_methanol, 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 V_t-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.