Structure of starch aerogel as affected by crosslinking and feasibility assessment of the aerogel for an anti-fungal volatile release

- Starch suspension was cross-linked, gelled and then freeze-dried to aerogel.
- The aerogel was loaded with trans-2-hexanal and coated with sorbitan monooleate.
- Cross-linking resulted in a higher gel hardness and crystallinity index value.
- Surface coating introduced a more sustained release character for the loaded hexanal.
- Coating decreased the lethality rate of Aspergillus cells inoculated on pistachio nut.

Starch suspensions were crosslinked with trisodium citrate for either 0 or 17 h, gelled and then freeze-dried to corresponding aerogels. The aerogel from the 17 h-crosslinked suspension was loaded with the antifungal compound, trans-2-hexenal, and coated with the surfactant, sorbitan monooleate. Aerogel hardness was increased by the citrate-mediated crosslinking, whereas its adhesiveness decreased. Starch gelation decreased the crystallinity index (CrI) from 59% to ≈23%; however, the pre-gelation crosslinking resulted in a higher CrI value (i.e. ≈38%) for the aerogel. The voids at the internal microstructure of the 17 h-crosslinked aerogel were more uniform and coating with surfactant closed the surface openings. The latter accordingly resulted in a more sustained release of the volatile, trans-2-hexenal, from the crosslinked starch aerogel and led to slower lethality of Aspergillus parasiticus cells inoculated on pistachio nuts compared with the non-coated condition.