1.Good sensory properties.
2.Phage resistance.
3.Viability during processing.
4.Stability in the product and during storage.
Good viability and activity of probiotics are considered prerequisites for optimal functionality. However, several studies have shown that non-viable probiotics can have beneficial effects such as immune modulation and carcinogen binding in the host (for a review see Ouwehand and Salminen, 1998 and Salminen et al., 1999). Thus, for certain probiotic strains it might be sufficient that they grow well during initial production steps (to obtain high enough numbers in the product) but they do not necessarily need to retain good viability during storage.