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

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.