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Cryogel based encapsulation of curcumin, an herbal extract, was successfully carried out with a ternary system of colloidal chitosan, κ-carrageenan, and carboxymethylcellulose sodium salt. The effects of chitosan concentration, κ-carrageenan/CMC ratio of the polymer suspension and molecular weight of chitosan on the sol–gel formation were investigated. The effects of cooling rate during freeze-drying and oil phase composition on the encapsulation yield and the release behavior of curcumin from the hydrogel were determined. And so were the effects of pH of the phosphate-buffered media and oil phase composition on the swelling of the specimens. The microstructure of the resulting specimens revealed core-shell nanoparticles (i.e. oil droplet for core and cryogel membrane for shell) entrapped in the cryogel matrix. The encapsulation yield for two types of suspensions was in a range of 83.9 to 99.6% when a high-MW chitosan was used. Controlled release of the encapsulated curcumin in an aqueous system could be maintained for 4 days, and the releasable amount of curcumin was in a range of 41.1 to 59.9%. The encapsulation yield as well as the released pattern and releasable amount of curcumin were significantly influenced by the cooling protocol used during freezing. Irrespective of the introduced oil phase composition, controlled release of curcumin was achievable when the cooling rate was sufficiently high at − 2.0 °C/min and, interestingly, either a burst release or a first order release could simply be achieved by changing the freezing condition.

Cryogel based encapsulation was attempted to entrap oil phase (containing curcumin) with a ternary system of colloidal chitosan, κ-carrageenan, and carboxy methylcellulose sodium salt (NaCMC). The cryotropic gel formation was investigated by varying the cooling rate during freezing and type of polymer suspension. The microstructure of the resulting curcumin cryogels revealed oil droplets entrapped in the cryogel matrix. The encapsulation yield for two types of suspension was found to vary from 83.89 to 99.37%. Controlled release of the curcumin in an aqueous system could be maintained for 4 days, and the released amount of curcumin was found to vary from 41.1-59.9%. The encapsulation yield as well as the released pattern and amount of curcumin were influenced by the cooling protocol used during freezing. The release patterns were found to be sensitive to the ambient aqueous pH and, interestingly, either a burst release or a first order release was achievable simply by changing the freezing condition. These results suggested that freezing could modify the gel formation of the present cryogel, and the resulting structural modification evidently controlled the oil encapsulation manner. The present ternary system (chitosan, κ- carrageenan, and NaCMC) is an interesting matrix for designing controlled release system in a food system.