Improving curcumin retention in oil-in-water emulsions coated by chitosan and their disperse stability exposed to thermal treatments

Curcumin-loaded (6% medium-chain triglyceride oil in water) emulsions were coated with chitosan and then treated with different thermal processes, including LTLT (low-temperature, long-time), HTST (high-temperature, short-time), and autoclave treatments. The mean size and zeta-potential of the emulsions linearly increased with increasing chitosan concentrations. All emulsions maintained their initial mean size after LTLT and HTST, but autoclaving increased the emulsion sizes. The size increment diminished with increasing chitosan concentrations. Moreover, 26.1% of the curcumin in non-coated emulsions was degraded during the autoclaving, whereas 83.1% of the curcumin was retained in emulsions coated with 1.0% chitosan. Thus, the emulsions coated with 1% chitosan are applicable to various thermal processing including LTLT, HTST, and autoclaving. All emulsions showed Newtonian fluid behavior, but viscosity increased with increasing chitosan concentrations. Therefore, the emulsion coated with a high chitosan concentration (more than 0.5%) showed enhanced storage stability in turbidimetric analysis despite its high polydispersity index.

Automated summary

This study investigated the effects of thermal processes on curcumin-loaded emulsions coated with chitosan. The results showed that chitosan concentrations affected the size and zeta-potential of the emulsions, and autoclaving increased the emulsion sizes. However, coating with chitosan effectively protected curcumin, with higher concentrations exhibiting enhanced storage stability.