Synthesization and characterization of lotus seed protein-based curcumin microcapsules with enhanced solubility, stability, and sustained release.

BACKGROUND Lotus seed protein (LSP) was extracted from lotus seed and was used to encapsulate curcumin with or without complexing with pectin. The physicochemical properties of LSP-based microcapsules, including solubility, stability, and in vitro sustained release were determined. The mechanism of interaction between curcumin, LSP, and pectin was revealed. RESULTS The encapsulation efficiency of curcumin was found to depend on LSP concentration and was highest (86.32%, w/w) at 50 mg/mL. The curcumin in Curcumin-LSP and Curcumin-LSP-Pectin powder particles obtained solubility of 75.15% and 81.39%, respectively, which achieved remarkable enhancement. The microencapsulation with LSP and LSP-Pectin matrix had a significant improvement effect on the antioxidant activity photostability, thermostability, and storage stability of free curcumin. The microencapsulated curcumin showed sustained control release in the gastric stage and burst-type release in the followed intestinal stage, presenting cumulative release rates of 64.3% and 72.4% from Curcumin-LSP and Curcumin-LSP-Pectin particles after the gastrointestinal digestion. The LSP-pectin complex produced microcapsules with higher solubility, smaller particle size, enhanced physicochemical stability, and increased bioaccessibility. Fourier transform infrared, circular dichroism spectra, and differential scanning calorimetry data indicated that the encapsulated curcumin interacted with LSP and pectin mainly through hydrogen bonding, hydrophobic, and electrostatic interactions. CONCLUSION This work shows that LSP can be an alternative encapsulant for the delivery of hydrophobic nutraceuticals with enhanced solubility, stability, and sustained release. The results may contribute to the design of novel food-grade delivery systems based on LSP vehicles, thereby broadening the applications of LSP in the fields of functional food. This article is protected by copyright. All rights reserved.