Fabrication and characterization of double (W1/O/W2) emulsions loaded with bioactive peptide/polysaccharide complexes in the internal water (W1) phase for controllable release of bioactive peptide

•Bioactive peptide (BP)/polysaccharides (P) complexes were successfully fabricated.•BP/P complexes were successfully entrapped within the W1-phase of W1/O/W2 emulsions.•BP/P complex-loaded W1/O/W2 emulsions showed >92% encapsulation efficiency of BP.•Higher temperatures induced greater leakage/diffusion of BP from W1/O/W2 emulsions.•Differences in the fatty acid composition of oil phases affected BP release. The objective of this study was to develop food-grade double emulsions containing bioactive peptide (BP)/polysaccharide (P) complexes and to investigate their thermal stability (e.g., BP release) at different temperatures. The BP/P complexes were formed via electrostatic interactions, and successfully encapsulated into the internal water phase of double emulsions with different oil phases. All emulsions clearly showed temperature dependence during storage. BP/P complex-loaded double emulsions showed higher thermal stability and lower release of encapsulated BP (45 °C: < 1%, 65 °C: < 30%) over time, which effectively prevented BP release within the emulsion system. For the effect of the oil phase, the BP released from double emulsions was in the order of MCT > coconut > canola oil. Thus, we concluded that BP release can be controlled in double emulsions by differently charged polysaccharides and oil types and that BP/P-loaded double emulsions can be utilized as functional ingredients for developing heat-sensitive food products.