Preparation and characterization of double-coated probiotic bacteria via a fluid-bed process: a case study on Lactobacillus reuteri

In this research, a specific fluidized bed coater, Wurster, was used to double-coat . The first layer of coating was shellac (16, 17 and 18% w/v) and sodium alginate (0.5, 1 and 1.5% w/v). The microcapsules coated by 1% sodium alginate showed the highest relative survival of bacteria (11.1%) after 1 h in simulated gastric conditions (pH 2) and was, therefore, selected as the first layer of the microcapsules. Chitosan (0.5, 1 and 1.5% w/v), and arabic gum (1.5, 3 and 6% w/v) were used for the second layer. The best second layer was determined on the basis of relative survival of bacteria after acidic (simulated gastric conditions) and heating (80 °C for 15 and 30 min) examinations. The results showed that the relative survival of bacteria in microcapsules with a second coat of 1% w/v chitosan was higher than the others in both acidic (11.6%) and heating (7.31% at 15 min and 0.63% at 30 min) conditions.