Spray freeze drying (SFD) was used to prepare highly porous beads from cellulose nanocrystals (CNCs). SFD is well known in food and pharma and has received some recent attention for drying CNCs. In this technique, CNCs are sprayed from a fine nozzle into a bath of liquid nitrogen where they form beads that are kept frozen until lyophilization. The rapid freezing templates the porous structure by the formation of ice crystals that reject the CNCs as impurities. Porous CNC beads were readily achieved however water stability without the use of chemical crosslinking was more complicated. Different approaches were employed to improve the water stability of these beads with varying success. Here, we present what worked and what did not, as well as characterization of the beads by optical microscopy, scanning electron microscopy, laser diffraction, BET surface area, and the controlled release of a model flavor compound by UV-Vis spectroscopy. We anticipate that this type of soft porous bead may be of use for the release of actives at different rates and at different locations along the gastrointestinal tract, dependent on the structural resilience of the beads in various biological environments.

Water-stable (or not) nanocellulose porous beads for controlled release applications

2019 Spring National Meeting

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