Stability and release properties of curcumin encapsulated in Saccharomyces cerevisiae, β-cyclodextrin and modified starch

Curcumin, a polyphenol with pharmacological function and colouring power, was encapsulated in baker’s yeast (Saccharomyces cerevisiae) cells, β-cyclodextrin (β-CD) and modified starch (MS) by various methods. The encapsulation forms were evaluated for their efficiency in overcoming curcumin’s heat, light and oxygen sensitivity (storage stability). The release (dissolution) profile of curcumin in simulated gastric (SGF) and pancreatic fluid (SPF) was, also, obtained. All the encapsulation forms drastically increased curcumin’s solubility in SGF. A rapid dissolution of curcumin was observed for β-CD and MS microcapsules in SGF while, in yeast microcapsules, a slow and prolonged release occurred, along with low degradation rate in SPF. All the microcapsules tested protected curcumin against oxidation in environments of elevated relative humidity (%RH) and yeast microcapsules stabilized curcumin at RH above 75.5%, where oxidation was significantly increased. Yeast cells offered better protection to curcumin than did β-CD or MS against deleterious photochemical reactions and against heat degradation following isothermal (inert or oxidative) heating at 200 °C. Heating at lower temperatures (isothermal and non-isothermal) revealed that β-CD and MS can also enhance curcumin’s heat resistance.