Physico-chemical approach for characterizing probiotics at the solid and dispersed states

A physico-chemical approach was used for characterizing and generating fingerprints of single (L. bulgaricus and S. thermophilus) and multiple (Vivomixx) probiotic species. Such a methodology included thermal, colloidal, and surface analyses of powder (solid-in-gaseous phase) and dispersed (solid-in-aqueous phase) samples. Decomposition and transition phases analyzed by thermogravimetry and differential scanning calorimetry provide specific qualitative and quantitative data that serve as a probiotic fingerprint, and therefore a product quality control for each sample. Investigation of colloidal and surface properties of dispersed samples by light scattering and contact angle measurements informs on the probiotic size average, electrokinetic charge, and surface hydrophobicity. Besides their relevance in identity control, the physico-chemical data are also useful in probiotic performance prediction, since they govern the most crucial microbial functionalities such as thermostability, aggregation, and adhesion.