Effect of full-fat goat's milk and prebiotics use on Bifidobacterium BB-12 survival and on the physical properties of spray-dried powders under storage conditions

The effects of full-fat goat's milk and/or inulin and/or oligofructose, as carrier agents, were investigated to improve the survival rates of Bifidobacterium BB-12, and the physical properties of the microcapsules under storage conditions. On the day of their manufacture, the microcapsules were evaluated for morphology, particle size, and distribution of fat and bifidobacteria. The viability of the bifidobacteria, moisture and fat content, water activity, solubility, bulk and tapped density, flowability, cohesiveness and color properties were evaluated for 120 days at 4 degrees C and 25 degrees C. The full-fat goat's milk powder with or without inulin as encapsulating agents showed the highest survival rates of Bifidobacterium BB-12 after spray drying and storage. Considering the bifidobacteria survival, both of these spray-dried powders showed the most desirable physical properties, i.e., lowest water activity and solubility, respectively. Both properties are highlighted for better stability of spray-dried powders, with microcapsules, during storage time. These results are credited to full-fat goat's milk (200 g L-1) and the presence of inulin (100 g L-1), besides the fat content showing a high correlation with the solubility values. The lowest volume occupied by the spray-dried powders was noted when oligofructose was used as the carrier agent. The samples that showed the presence of cracks influenced negatively on the bifidobacteria viability. These cracks were responsible by the greater water escape, resulting in powders with more desirable lower water activity. In relation to the color parameters, lower stability was noted when oligofructose was used, while the best stability was also noted for the powders with full-fat goat's milk and/or inulin. During storage time, the best performance was achieved by the microencapsulation process that used only full-fat goat's milk and/or inulin and storage at 4 degrees C.