Complexation of curcumin using proteins to enhance aqueous solubility and bioaccessibility: Pea protein vis-à-vis whey protein

Curcumin faces challenges such as poor aqueous solubility and limited bioaccessibility which limits its oral therapeutic applications. This work evaluated the complexation of curcumin using pea protein isolate (PPI, leguminous protein) vis-à-vis whey protein isolate (WPI, animal protein) to overcome these limitations. Thermodynamic parameters (ΔH and ΔS) indicated the interaction to be hydrophobic in nature. While WPI-curcumin complex showed better aqueous solubility for curcumin than PPI-curcumin complex at varying pH (3, 5 & 7), the PPI-curcumin complex showed better solubility at higher temperature of 80 °C. The solubility of curcumin in WPI-curcumin and PPI-curcumin complex at pH 7 was 1.16 mg/g and 1.02 mg/g, respectively. The protein curcumin solutions were further spray dried and characterized for surface hydrophobicity, crystallinity, thermal properties, and surface morphology. Both the proteins showed a similar score for bioaccessibility of curcumin from their respective complexes. Thus PPI can be a good non-dairy protein alternative for curcumin delivery.