High dispersity, stability and bioaccessibility of curcumin by assembling with deamidated zein peptide.

Many liposoluble nutrients are restricted for applications in foods due to their poor water solubility, stability and bioavailability. Here, a deamidated zein peptide with a broad molecular weight distribution and high carboxyl and hydrophobic residue contents was used to solubilize curcumin. The complex nanoparticles of curcumin and the peptide were produced through self-assembly in aqueous solutions. Fluorescence and infrared spectra revealed that hydrogen bonding and hydrophobic interactions actuated the assembly. The complex nanoparticles had a curcumin loading capacity of 31.9% and completely inhibited curcumin crystallization. The peptide effectively protected curcumin from decomposition in aqueous solutions by inhibiting the reaction between dissolved oxygen and curcumin. The nanoparticles presented excellent freeze-drying/re-dispersion stability without any lyoprotectant. The curcumin bioaccessibility of the nanoparticles was 75% and the nanoparticles exerted a significant antioxidant effect after oral administration in mice. This study indicates that the nanoparticles are potentially useful as an antioxidant additive in foods.