Investigation of the aerobic biodegradability of several types of cyclodextrins in a laboratory-controlled composting test

The biodegradation of several types of cyclodextrins (CDs) under laboratory-controlled composting conditions was investigated. CDs are used in a broad range of applications in food, pharmaceutical, medical, chemical, and textile industries because of their specific chemical characteristics related to their hydrophobic interior and hydrophilic exterior. The three naturally occurring cyclodextrins alpha-CD, beta-CD, and gamma-CD proved to be completely and readily biodegradable. Chemical modi. cation of these basic compounds can have a major impact on the biodegradation rate and final biodegradation percentage. Fully acetylated alpha-CD and beta-CD were found to be nonbiodegradable during 45 days of composting. Reducing the degree of acetylation had a positive effect on the biodegradation. Complete biodegradation was obtained for partially acetylated beta-CD with a degree of substitution (DS) of 7. The methylation (DS=13) of beta-CD resulted in an undegradable compound during the 47 days composting, while (2-hydroxy) propyl-beta-CD reached a plateau in biodegradation at a percentage of 20%. The incorporation of the antimicrobial agents imazalil and allyl-isothiocyanate into beta-CD had no negative impact on biodegradation, which makes these antimicrobial agents/CD complexes suitable for incorporation into biodegradable active packaging.