Lactobacillus plantarum protection by entrapment in whey protein isolate: κ-carrageenan complex coacervates

•Biopolymers ratio and pH affected significantly the complex coacervates properties.•Higher protein to polysaccharide ratio produced higher cells survivability.•Higher protein to polysaccharide ratio produced higher viscoelastic moduli.•Entrapped cells could be clearly identified in light and SEM micrographs.

Lactobacillus plantarum (L) was entrapped in whey protein isolate (W) and κ-carrageenan (K) complex coacervates (CC). The interaction window leading to W–L–K complexation at different pH values and components ratio was established by ζ-potential measurements and turbidimetric analysis. CC obtained at pH values of 4.0 and 4.5 and W:K weight ratio of 16.7:1 yielded cells entrapment efficiency of 39.6%, a significantly higher viability of 9.75 log cfu g−1 after exposure to low pH and of 9.66 log cfu g−1 after exposure to bile salts, than free cells (9.51 log cfu g−1and 5.93 log cfu g−1, respectively), with respect to an initial cells count of 9.78 log cfu g−1. Higher survivability of cells occurred in CC exhibiting a more compact microstructure and higher viscoelastic properties. Light and scanning electron micrographs clearly show that L. plantarum cells were effectively entrapped in the CC matrices.

Graphical abstractWhey protein isolate-Lb. Plantarum-κ carrageenan complex coacervates.Figure optionsDownload full-size imageDownload as PowerPoint slide