Coconut Milk as a Protective Co-Matrix Boosts Bifidobacterium animalis H22B648 Viability in Stress-Exposed Alginate Hydrogels

Coconut milk is a natural, food-grade emulsion with inherent safety and pleasant flavor, yet it remains underexplored as a functional protectant for bifidobacteria. This study incorporated a coconut milk-based protectant (CMP) into sodium alginate (SA) hydrogels (20-30 g/L) to encapsulate Bifidobacterium animalis H22B648 (SA-P-B). Results showed that the incorporation of CMP increased viscosity but decreased the gel strength after solidification. SA-P-B exhibited a higher swelling ratio and delayed disintegration in simulated intestinal fluid. Compared to SA-B (without CMP), SA-P-B demonstrated 3.2-3.8-fold higher apparent encapsulation efficiency, over 10-fold higher lyophilization survival, 46.3-64.4-fold higher viability after gastrointestinal digestion, and significantly improved storage stability and heat tolerance (only a 1.97-2.24 log CFU/g reduction in SA-P-B versus >7 log CFU/g in SA-B). Scanning electron microscopy revealed a denser microstructure in SA-P-B, with fewer exposed bifidobacteria. Differential scanning calorimetry indicated that heat absorption associated with the phase change of coconut oil may mitigate thermal stress, enhancing the survival of bifidobacteria. Thus, CMP markedly enhanced the environmental stress tolerance of alginate-encapsulated bifidobacteria, highlighting its potential as a plant-based protective strategy for bifidobacteria applications.