Development of microparticulate systems for intestinal delivery of Lactobacillus acidophilus and Bifidobacterium lactis

In the present study intestinal delivery systems resistant to gastric juice, loaded with the probiotic bacteria Lactobacillus acidophilus LA14 and Bifidobacterium lactis BI07, were produced by the polyelectrolyte complexation. First, beads were prepared by the traditional extrusion method and nine formulations were developed using alginate as main carrier and the biopolymer, xanthan gum (XG), as hydrophilic retardant polymer or the cellulose derivative, cellulose acetate phthalate (CAP), as gastro-resistant polymer. The results showed that the incorporation of the 0.5% (w/v) of XG or the 1% (w/v) of CAP within the 3% (w/v) of alginate solution increased the survival of the probiotic bacteria in acid conditions from 63% of the freeze-dried bacteria up to 76%. Subsequently, these formula was used to prepare smaller microcapsules by means of an atomization device. Despite of the high viscosity of the biomass suspension, the spraying system produced spherical and non-aggregated microcapsules able to survive in harsh condition better than beads: the survival of the probiotic bacteria after acid incubation was 91%. The performance of the microcapsules in simulated gastric fluid (SGF) containing pepsin and in gut medium (GM) containing bile salts was excellent (viability > 95%). Furthermore, the viability of probiotic bacteria was maintained after an incubation of 24 h in GM. Finally, stability tests performed at 5 °C highlighted a bacterial viability of about 82% and 70% after 6 and 9 months, respectively.