Humectant properties and thermal behavior of inulin as a potential bio-based humectant for tobacco shreds

Developing safe and sustainable humectants for tobacco shreds has gained increasing interest owing to the limitations of conventional polyol-based additives. In this study, native inulin (NA), a storage polysaccharide abundant in several industrial crops, was fractionated into short-chain (SC) and long-chain (LC) fractions. All three inulin fractions were assessed for their physicochemical properties and film-forming ability. Then, the application on tobacco shreds was evaluated by moisture adsorption-desorption experiments, water state distribution, microstructural stability and pyrolysis behavior. The results revealed that SC exhibited the highest solubility, while all inulin samples showed comparable viscosity to propylene glycol. NA possessed better thermal stability, whereas SC and NA demonstrated superior film-forming ability compared with LC. The moisture retention tests indicated that SC and NA provided stronger moisture retention than propylene glycol under low-humidity, which was consistent with their better preservation of shred surface integrity as shown by microstructural analysis. Kinetic analysis further revealed that SC possessed favorable bidirectional moisture-regulation capacity. Pyrolysis analysis showed that the addition of inulin altered volatile product distribution and reduced the abundance and diversity of benzene homologs. These findings demonstrate that SC and NA are promising crop-derived bio-based alternatives to conventional humectants in tobacco products.