Structural modulation of alginate hydrogels by β-Lactoglobulin nanofibrils and embedded diacylglycerol particles for dual active delivery

Sodium alginate (SA) hydrogels have attracted considerable attention due to their excellent biocompatibility and protective effects on bioactive ingredients. However, single−polysaccharide network has insufficient mechanical strength, poor release control, and low efficiency in co−loading of hydrophilic/hydrophobic actives. In this study, β-lactoglobulin nanofibrils (BLGF) with long fibril (LF) or worm−like fibril (WF) morphology were incorporated into the SA network via Ca 2+ crosslinking. The resulting composite hydrogels significantly enhanced water−holding capacity and swelling properties reaching maximum values of 98.52% and 46.84%, respectively. While WF showed a higher binding interaction force with SA, LF demonstrated a more efficient intertwining effect, maintaining a dense gel network. Introducing solid lipid nanoparticles (SLN) resulted in an encapsulation efficiency of 88.19% for β-carotene and a loading rate of 81.57% for folic acid. The composite hydrogel exhibited pH−responsive release reflected by the low release (<5%) of β-carotene in the gastric phase and accelerated release in intestinal fluid. The hydrogel also exhibited a diffusion-controlled release pattern for folic acid and an erosion-controlled release pattern for β-carotene. By varying the SA−LF/WF ratio, coordinated control over the diffusion rates of bioactives was achieved. This study clarifies the structural enhancement provided by BLGF in composite hydrogels and offers insights for designing dual-delivery systems.