Tamer Uyar, holder of Szejtli award (2014) and his team published studies on the gamma-cyclodextrin (γCD) inclusion complexes with essential oil compounds linalool and geraniol encapsulated in pullulan nanofibers using an electrospinning technique. The nanofibers were produced with the initial essential oil content of ~ 11% (w/w) and ~ 74 to 77% of these volatile compounds could be preserved in pullulan/essential oil-γCD nanofibers due to inclusion complexation. On the other hand, only ~ 15 to 23% of essential oil could be kept in the case of pullulan/EO nanofibers in the absence of γCD. The essential oil-γCD inclusion complexation also ensured improved thermal stability for essential oil compounds, and their volatilization shifted from ~ 119–139 to ~ 239–292 °C ranges for pullulan/essential oil-γCD nanofibers. Moreover, pullulan/essential oil-γCD nanofibers displayed substantial long-term storage stability and, ~ 48 to 64% of essential oil content was still preserved even after 4 weeks, while this ratio was in the range of ~ 0.3 to 4.5% in the case of pullulan/essential oil nanofibers. The pullulan/geraniol-γCD nanofibers displayed an effective antibacterial activity against Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria, and overwhelmingly better performance compared to pullulan/geraniol nanofibers due to the inclusion complexation.
Cemical structure of linolaol, geraniol and pullulan
Pullulan is a polysaccharide polymer consisting of maltotriose units, also known as α-1,4- ;α-1,6-glucan’. Three glucose units in maltotriose are connected by an α-1,4 glycosidic bond, whereas consecutive maltotriose units are connected to each other by an α-1,6 glycosidic bond. Pullulan is produced from starch by the fungus Aureobasidium pullulans. Pullulan is mainly used by the cell to resist desiccation and predation. As an edible, mostly tasteless polymer, the chief commercial use of pullulan is in the manufacture of edible films that are used in various breath freshener or oral hygiene products such as Listerine Cool Mint of Johnson and Johnson (USA) and Meltz Super Thin Mints of Avery Bio-Tech Private Ltd. (India). Pullulan and HPMC can also be used as a vegetarian substitute for drug capsules, rather than gelatine. As a food additive, it is known by the E number E1204. (Wikipedia)
Celebioglu, A., Hsiung, E., Aboelkheir, M. et al. Encapsulation of Essential Oil-Cyclodextrin Inclusion Complexes in Electrospun Pullulan Nanofibers: Enhanced Storage Stability and Antibacterial Property for Geraniol and Linalool. Food Bioprocess Technol (2024). https://doi.org/10.1007/s11947-024-03534-6