Bovine serum albumin cold-set emulsion gel mediated by transglutaminase / glucono-δ-lactone coupling precursors: Fabrication, characteristics and embedding efficiency of hydrophobic bioactive components

Encapsulation and protection of hydrophobic bioactive compounds using food-based sustainable materials are challenging issues in recent decade. Herein, we provided a feasible strategy to fabricate bovine serum albumin (BSA) cold-set emulsion gel by using microbial transglutaminase (MTGase) and glucono-δ-lactone (GDL) as substrate precursors. Its embedding potential towards quercetin and vitamin E (VE) were thereby evaluated. The results showed that hardness and springiness of the gels decreased along with increasing of GDL (≥0.3%, w/v) in the presence of 0.1% (w/v) MTGase. Storage modulus (G′) and loss modulus (G'') reached the maximum at 0.3% (w/v) GDL, while the water-holding capacity (WHC) of gels (≥85% (w/v)) was positively correlated to GDL addition. The pattern of confocal laser scanning microscope (CLSM) further confirmed the occurrence of smaller oil droplets in fabricated gels with relatively high abundance of GDL. Consequently, the embedding efficiencies for quercetin and VE reached up to 94.80% (w/v) and 97.94% (w/v) respectively. The harder gels had much better controlled-release performance than the softer ones. The work shed light on the rational design of food protein gels to protect, stabilize and delivery of small hydrophobic bioactive molecules.