why does salt preserve foods?

Answer 1

Because it draws water away from it through osmosis, water that would be required by bacteria to decompose the food. Salt also draws water away from bacteria, killing them.

Answer 2

Salt performs several functions in preserving food:

1. Salt shifts the growth conditions to favor Gram-positive instead of Gram-negative bacteria. Most human pathogens are Gram-negative. These include Salmonella, Escherichia coli and Clostridia. There are only a few Gram-positive pathogens, such as Listeria and Staphylococcus.

2. Salt removes available water from the food by changing the osmotic pressure. This makes it harder for bacteria to obtain water to grow. The availability of water in food is called "water activity", and every species of bacteria has a minimum water activity below which it won't grow. Most pathogens will not grow below a water activity of 0.92 (pure water is 1.0).

3. Salt in itself eventually becomes poisonous to the microbes by creating an electrolyte imbalance within the cell.

4. A brine (salt / (salt + moisture)) of 3.5% will normally prevent serious pathogens (e.g., Clostridium botulinum) from growing. Brines of
more than 10% will normally prevent all pathogenic bacteria from growing.

Answer 3

It took scientists a long time to figure this one out.Some bugs simply slide off the surfaces of foods preserved with salt and can't start to do their thing. Other bugs are simply lyced (spelling?)(cell walls ruptured by the osmatic pressure caused by the high concentration of salt on the surface of the preserved item.)

Answer 4

Because it draws out all the moisture, so the food gets preserved through dehydration.