**5. Conclusion**

The wettability of probiotic powders deserves a great scientific and technological attention, as for other food and non-food ingredients and products in various sectors. Beyond its evident importance in the dispersibility and stability of the powder containing live microorganisms and other components in contact with fluids, it is a crucial indicator of the cell adhesion capacity and cell viability improvement through encapsulation and coating processes. Its accurate determination with the appropriate techniques and data processing models is the key to progress in getting insight into the probiotic action mechanisms, and in improving the probiotic containing product qualities and performance. However, there are only a few available scientific data from probiotic powder wettability studies in the literature compared to contact angle measurements with various techniques. Three sample preparation and measurement techniques such as powder compact discs and microbial lawns by sessile drop, and a packed-bed column using rise capillary, can be distinguished. Subsequently, two fitting models based on Washburn equation and Darcy's law may be used based on the experimental recorded data. In particular, Darcy's law combined with the semiempirical Kozeny-Carman approach provides a potential prediction of powder porosity or permeability. This methodology will open a new research route on the impact of the microbial powder particle size, shape, aggregation, adhesion, biofilm formation on the formulation performance and product stability, as well as on the cell viability and activities for human, animal, plant, and environment, in short, on our ecosystem health.
