Curcuminoids: A multi-faceted review of green extraction methods and solubilization approaches to maximize their food and pharmaceutical applications

Curcuminoids, chief polyphenols in Curcuma longa L. rhizome have extensive culinary and medicinal applications. In medicine, curcuminoids exhibit potential health benefits including anticancer, antimicrobial, antitumor, antidiabetic, neuroprotective, antioxidant, and cardioprotective properties. Additionally, curcuminoids are commonly used in culinary as a spice, flavoring agent, pigment, and food additive. Considering the potential value of curcuminoids and their difficulty to be synthesized, the development of effective extraction and purification techniques for their recovery from natural sources seems warranted. To meet the demands of food and nutraceutical industries, an effective curcuminoids’ extraction process should adhere to green chemistry principles in order to ensure efficiency, safety, environmental sustainability, minimal contaminants, and cost-effectiveness. This review focuses on several curcuminoids’ separation methods including traditional techniques, such as Soxhlet, maceration, and solvent extraction, as well as green advanced technologies including ultrasound-assisted extraction, enzyme-assisted extraction, extractions via pressurized liquid, supercritical fluid, pulsed electric field, three-phase partition, and deep eutectic solvents. A comparison is presented among the different extraction methods highlighting their advantages and limitations to aid future users in deciding on the best method that suit their needs. Lastly, approaches reported on improving curcuminoids’ solubility are also presented as part of this study to enhance their bioavailability and ultimate efficacy.