Enhancement of stability and controlled release of phycocyanin via W/O/W double emulsions prepared with propylene glycol alginate and whey protein isolate.

The effectiveness of phycocyanin (PC) is limited by its poor stability. Herein, we evaluated the protective effect and release of PC from double emulsions (DEs) stabilized by propylene glycol alginate (PGA), whey protein isolate (WPI), and a WPI-PGA (WP) complex. Results showed that WP complex was formed via hydrogen bonding, as well as hydrophobic and electrostatic interactions. The contact angle of WPI, WP complex, and PGA was 66.59°, 75.79°, and 84.49°, respectively. PGA-stabilized DEs exhibited the highest apparent viscosity and strong viscoelastic properties. The WPI-stabilized DEs showed the biggest particle size (33.09 μm), lowest encapsulation efficiency (EE, 98.65 %), and the worst stability against freeze-thaw cycles, centrifugation, thermal conditions, and storage. Conversely, PGA-stabilized DEs showed the smallest particle size (9.73 μm), highest EE (99.48 %), and superior stability. The in vitro digestion analysis revealed that DEs stabilized by PGA and a WP complex exhibited better release of PC during simulated gastrointestinal digestion compared to WPI-stabilized DEs, with the release behavior being controlled by diffusion. This study highlighted the potential of PGA, both alone and in complexation with WPI, as effective stabilizers for PC-loaded DEs. Additionally, it provided novel insights into W/O/W DEs as delivery systems for hydrophilic bioactives that possess poor stability.