Abstract
The use of polluting and toxic solvents for curcumin extraction and its low water solubility are major drawbacks limiting the exploitation of curcumin as medicinal resource. To date, water extraction of curcumin from turmeric remains a challenge. The work presented here solves both problems with a simple, one-step strategy based on the use of ultrasounds. The combined extraction and encapsulation of curcumin from C. longa using nanoemulsions, followed by freeze-drying of the curcumin-loaded nanoemulsions called extremulsions, has been reported in this study. Different extraction media and processing parameters were investigated. An ultrasonic probe was used (using different variables such as sonication time, duty cycle and ultrasonic intensity) to develop this one-step, water-based technique to extract curcumin directly from turmeric. Optimal formulation and extraction were achieved using oil droplets composed of tributyrin and a mixture of triglycerides C8-C10 stabilized with TPGS 1000 in water. The extraction of curcumin using extremulsions was compared to conventional Soxhlet-assisted extraction in acetone taken as reference yield (100%). Extremulsions afforded a 63% recovery rate of curcumin. In addition, the preservation of the physicochemical properties (droplet size and size distribution) of extremulsions during the freezedrying process was investigated. Dry extremulsions with a fast redispersion speed were successfully obtained after optimization of freeze-drying parameters. The results of this study demonstrate the potential of this original process combining in a single step solvent-free extraction and encapsulation of liposoluble natural products, and its efficient use for dualextraction and encapsulation of curcumin from turmeric. This study also provides a solution to the problem of bioavailability of curcumin, due to its low water solubility, through dry extremulsions of curcumin.