Curcumin-protein complexes: Technological and biological functionalities

Complexation with proteins has been employed as an efficient method to increase the solubility, stability, and bioavailability of curcumin (Cur) as a bioactive hydrophobic compound. Different animal (from milk, egg, meat, and insects) and plant proteins (from soy, pea, walnut, mung bean, corn, etc.) have been used to fabricate Cur-protein complexes (Cur-Pro). This review mainly presents the technological and biological functionalities of Cur-Pro. Accordingly, the Cur-Pro prepared by different methods such as the simple complexation and pH-shifting approach were reviewed. This was followed by investigating the functional (interfacial activity, flow behavior, and gelation), bioactivity, release, and in vitro digestibility of the Cur-Pro. The results showed that Cur-Pro have excellent biological activities. Accordingly, the solvent-free pH-shifting approach was a more efficient method compared to the simple complexation to fabricate Cur-Pro. Also, the structural modification of proteins by different treatments e.g., aggregation (especially nanofibrillation), cross-linking, and ultrasonication can change their ability to form soluble complexes with Cur. The functional properties of Cur-Pro including rheological, gelation, and interfacial properties, show that the technological properties of proteins are modulated through complexation with Cur. Cur-Pro can protect Cur against the gastric digestion and provide a controlled-release in the intestinal phase. The in vitro digestibility of proteins in the simulated gastrointestinal conditions is influenced by Cur binding. Generally, Cur-Pro can be used as promising multi-functional ingredients to develop natural and safe functional foods for human health considerations.