Saturday, April 21, 2007

Food Preservation by High Osmotic Pressure

Food Preservation by High Osmotic Pressure
Bacteria reach osmotic equilibrium by two means:

1. In hypertonic environments the volume of the protoplasts will shrink, and
2. In hypotonic environments the rigid wall will resist increase in protoplasts volume at a limiting volume of water; equilibriums results from turgor against the wall.

The rigid wall present in bacteria cells enable most bacteria to tolerate even extremely dilute environments. Osmotic equilibrium is achieved by development of turgor pressure against the wall. The wall of gram-positive micrococci can withstand 22 atm of pressure.

Although the walls of gram-negative rods have lower tensile strength, the wall is sufficiently strong to retain the turgor pressure if the cell is suspended in water.
Food Preservation by High Osmotic Pressure

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