Freezing and freeze-drying of Pickering emulsions stabilized by starch granules

• Oil powders with 80% oil were produced from starch granule stabilized emulsions by freeze-drying.
• The oil powders could be reconstituted to stable emulsions.
• Partial gelatinization of starch increased freeze-drying stability of emulsions.
• Dispersed phase melting point affected freeze-drying stability of the emulsions.
• Different freezing methods imposed different changes on stability of the droplets.

The aim of this study was to investigate the possibility to produce novel powder materials based on chemically modified starch granule stabilized Pickering oil-in-water (O/W) emulsions. This study also investigated the effect of partial starch gelatinization in situ, dispersed phase type (two oil types with different melting points), freezing method and thawing, and freeze-drying and rehydrating on the overall properties of the emulsions. The emulsions showed high freeze–thaw stability. The results of this study demonstrated the feasibility of the production of oil containing hydrocolloid-based powders, through combination of heat treated or even non-heat treated starch Pickering emulsions and freeze-drying. The final powders comprised high weight percentage of oil (over 80%, w/w). Upon rehydration of powders, the starch stabilized oil drops were found to be only moderately affected by the process with some aggregation observed.

Oil containing powders can be produced with relatively high oil content (80%) from starch granule stabilized Pickering emulsions where adsorption and partial gelatinization of starch granules at the oil–water interface protects the integrity of droplets during freezing and freeze-drying.Figure optionsDownload as PowerPoint slide