Effect of microencapsulation methods on the survival of freeze-dried Bifidobacterium bifidum

Abstract

Six kinds of Bifidobacterium bifidum microcapsules were prepared by extrusion methods, emulsion methods and coacervation methods. Effects of preparation methods on the survival of encapsulated B. bifidum were examined. Results showed that microcapsules prepared by emulsion method with alginate and chitosan exhibited the best protection for B. bifidum. The diameter was 10-20 mu m, encapsulation efficiency was 90.36% and the live cell amount was 3.01 x 10(9) cfu/g after freeze-drying. Encapsulated cells exhibited significantly higher resistance to artificial gastrointestinal juice and the cell numbers were above 10(9) cfu/g after exposure to simulated gastric (pH 1.2) and bile salt (1%, w/v). Cell numbers of microencapsulated B. bifidum was 8.61 x 10(8) cfu/g after storage at 37 degrees C, relative humidity 60%-65% for 3 months. Results indicated microcapsules prepared with alginate and chitosan by emulsion method could successfully protect B. bifidum against adverse conditions and it might be useful in the delivery of probiotic cultures as a functional food.