Thermal and water sorption properties of Bifidobacterium BB-12 microcapsules obtained from goat's milk and prebiotics

Abstract

The spray-dried powders with Bifidobacterium BB-12 microcapsules with full-fat goat's milk and/or prebiotics (inulin and/or oligofructose), were characterized about their thermal and water sorption properties. The samples' thermal properties showed that the addition of prebiotics contributed to the higher thermal stability, highlighting the microcapsules produced with inulin. Regarding the water sorption properties, the Peleg model fitted well to the experimental data, providing adequate values of the initial mass transfer rate. The isotherm found for the sample with full-fat goat's milk with or without oligofructose was a Sigmoid Isotherm (Type II), commonly observed in most foods. The inulin use resulted in a change from Type II to Type III isotherm curve, where the molecular relaxation mechanisms and the adsorption forces are weak. Therefore, the relative humidity conditions above 43% and 11% can be responsible by a decrease of the storage stability of spray-dried powders, with microcapsules.