Re: Why do bananas seem to melt when they are coated with table salt?

Salt can be used as a preservative in fruit, it just wouldn't be very 
appetizing.  Salt is normally used in products where the saltiness is 
expected and acceptable such as beef sticks or jerky.

Salt can preserve in two ways:
1.  Many microorganisms are salt intollerant, i.e. they can not grow in 
high concentrations.  Normally we are talking a salt level of around 3%.  
This much salt is pretty intense and not very compatible with fruit 
flavors.
2.  By reducing thw water activity (Aw) of the product.  Aw is basically a 
measure of the relative humidity of a product.  Salt very effectively 
attracts and hold water, making it unavailable for use by microorganisms 
for their own growth and metabolism.  Most bacteria can't grow when the Aw 
is <.92 and molds at <.85.

In reality these two mechanisms may work together to preserve a product.  
In fruits they would result in a salty, dry, tough texture.  In the case 
of a banana salt would cause it to shrink enormously.  Bottom line is that 
flavor and texture would be unacceptable.

With fruits you may see another substance added for the same end effect as 
salt, i.e. sugar.  While sugar doesn't have the anti-bacterial properties 
of salt it does absorb moisture and lower the Aw.  Example, candied fruit.