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Name: Yona K.
Status: Student
Age: 15
Location: N/A
Country: N/A
Date: N/A 

How and why exactly does sodium chloride affects microorganisms? or bacteria? In another word, how does preservative(salt) works?

Life depends on water. Every living cell is a little salt-water bag. But that concentration of salt has to be carefully controlled. It a very high-salt environment, the process of diffusion sucks the water out of the cell (as the water is trying to dilute the outside environment). This increases the cell's internal salt-concentration until the cell can no longer function and dies. If you are preserving food, those cells are already dead.

So adding salt kills the only remaining living things -- microorganisms -- so they do not cause the food to spoil.

Christine Ticknor, Ph.D.

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