Growth adaptation of probiotics in biopolymer-based coacervatestructures to enhance cell viability

a b s t r a c tThe effect of inoculum size and growth of probiotic cells inside biopolymer-based coacervate structures,made from whey protein isolate and gum arabic, and a dual encapsulation method of complex coacervationcoupled with ionotropic gelation on the survival of probiotics was evaluated under adverseenvironmental conditions; i.e. low pH, heating, and simulated gastric juice (SGJ). The encapsulatedbacteria metabolized nutrients and multiplied within the coacervate structural assemblies, pointing to arather open carrier-delivery system for microbial cells, allowing the exchange of metabolites and nutrientswith the bulk liquid medium. Encapsulation of probiotic cells at low counts and subsequentgrowth improved cell viability upon heating or exposure to SGJ. When cells entrapped in complex coacervateswere subsequently embedded in Ca2þ-alginate gel microspheres, the remaining viable countsat pH 2.0 for 3 h were even higher by almost 1 logCFU/g. Overall, an initial low inoculum size of bacteriain complex coacervates, followed by culture growth (adaptation stage) and subsequent entrapment inalginate microspheres greatly enhanced the cell viability of probiotic cultures.