How do salts and sugars work to preserve food?

Answer 1

This has to deal with osmosis-the diffusion of water across a semipermeable membrane (like the cell membrane).

What happens is water will travel from solutions of low concentration of solute to high solute concentrations. If you load food with salt or sugars, then it has a very high concentration of solutes, and so any kind of living cells on the food will lose water due to osmosis.

Basically, the water is sucked out of bacteria or fungi living on the food, and the resulting loss of water dehydrates organisms and kills them.

It's the same principle of putting salt on slugs to watch them shrivel up.

Answer 2

Dehydration, and providing an environment with too little free moisture to support new life.

Answer 3

prevents bacterial growth by creating a hyperosmotic envrionment.