Whey proteins-folic acid complexes: Formation, isolation and bioavailability in a Lactobacillus casei model

•β-lactoblobulin and whey proteins based complexes for folic acid were generated.•The mixed solution experimented spontaneous phase separation at pH 3.•Electrostatic forces would be the main driving force for complexes formation.•Bioavailability of FA did not decrease in complexes.•This simple process results efficient and non-expensive for food applications.