Preparation and Stability Study of Co-Encapsulated Particles of Curcumin or Quercetin with Lactobacillus rhamnosus GG

This study developed and characterized a hierarchical co-encapsulation system for the delivery of hydrophobic polyphenols (curcumin or quercetin) and the probiotic Lactobacillus rhamnosus GG (LGG). The system was constructed through the self-assembly of zein to form a hydrophobic core for the polyphenols, followed by complex coacervation with debranched starch and chitosan to form an outer hydrophilic layer for LGG. Structural analyses using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and confocal laser scanning microscopy verified the successful formation of the core-shell structure and the transformation of crystalline polyphenols into an amorphous state. The co-encapsulated particles exhibited high encapsulation efficiency (>95% for both polyphenols and LGG) and encapsulation yield (>80% and >75%, respectively). The encapsulation significantly enhanced the antioxidant capacity of both polyphenols in DPPH and ABTS assays, with co-encapsulation of LGG providing a further enhancement. Moreover, the hierarchical structure effectively protected LGG, markedly improving its survival under simulated gastrointestinal conditions and during storage at 4 °C and -20 °C, with quercetin offering stronger protection than curcumin. These findings demonstrate that this co-encapsulation strategy delivers simultaneous protection to both probiotics and polyphenols, providing a robust approach for improving the stability and functionality of multiple bioactive components.