The CSIR has developed solvent-free ‘green’ encapsulation technologies for sensitive actives used in animal and human health such as probiotics, proteins, vaccines, drugs, vitamins and bioactive plant extracts to enhance their shelf-life stability and/or bioavailability.

The encapsulation of actives is generally done to improve their stability during storage and/or consumption, for delivering the active at a targeted site such as the stomach or intestines, or to obtain a specific release profile, such as rapid release, slow release or delayed release and/or to improve the solubility of the active. Conventional encapsulation methods expose active ingredients to organic solvents and high-process temperatures, which can have a detrimental effect on their viability, specifically for sensitive actives such as proteins, bacteria and vitamins.

The CSIR has developed encapsulation technologies in which supercritical carbon dioxide (scCO2) is utilised as a processing medium for the encapsulation of sensitive actives. Supercritical CO2 is particularly suitable as a processing agent for sensitive actives as it requires low processing temperatures (31.1ºC) and pressures (73.8 bar); eliminates the need for toxic organic solvents; encapsulation occurs in an oxygen- and moisture-free environment and no residual solvent exists in the final product.

The CSIR’s scCO2 encapsulation technologies are based on polymer complexation. Researchers have designed these complexation technologies to be pH-responsive, resulting in the active ingredients being protected in acidic environments, but released in alkaline environments, such as the intestinal fluid. In addition, the ‘close-knit’ structure resulting from the complex provides a barrier to oxygen and moisture.  With this technology, the CSIR has demonstrated improved shelf-life stability of probiotics, as well as improved survival through the gastro-intestinal track.

The scCO2 encapsulation technology also improves the aqueous solubility and thus intestinal absorption of sensitive actives. Researchers have developed formulations using scCO2, whereby the aqueous solubility of bioactive plant extracts is improved. 

The combination of the ‘soft’ processing conditions offered by scCO2 and the unique properties of the polymer complexes have been shown to improve the overall stability, survival and/or bioavailability of bacteria (probiotics) and bioactive plant extracts, such as flavonoids and polyphenols.

The abovementioned technologies can be extended to improve the stability and bioavailability of other sensitive actives such as vitamins, enzymes and vaccines.