Fundamentals of Microbiology

2.2.6 Freezing

When frozen, the crystallization of the water results in the formation of tiny pockets of concentrated solution of salts, which gets crystallized only below the eutectic point (about – 20^oC for NaCl). The localised high salt concentration and ice crystals damage the bacteria. Only some of the cells are killed. Repeated freezing and thawing reduces the viability of most cells.