Probiotic encapsulation in water-in-water emulsion via heteroprotein complex coacervation of type-A gelatin/sodium caseinate

The production of dried probiotic bacterial cells that are shelf stable at room temperature remains challenging. In this work, the potential of encapsulation of probiotic Lactobacillus reuteri using heteroprotein complex coacervation (type-A gelatin/sodium caseinate, GE/Cas) was compared to a protein/polysaccharide complex coacervation (type-A gelatin/gum arabic, GE/GA). The optimal pH and GE/Cas ratio for formation of water-in-water emulsions were found to be pH = 6.0 and GE/Cas = 2.0. L. reuteri TMW1.656 survived spray drying without loss of viability; the survival after simulated digestion, heating and ambient storage decreased in the order GE/Cas ≥ Cas > GE/GA > GE. The improved protection of the GE/Cas matrix was related to a reduced hygroscopicity, solubilization and wettability, and may be caused by the relatively higher hydrophobicity of GE/Cas heteroprotein coacervation system. To the best of our knowledge, this is the first study employing heteroprotein coacervation to encapsulate probiotics.