Food preservation is the addition of chemicals substances to the food.
They prevent the spoilage of food due to microbial growth.
They prevent the rancidity of food and inhibit the growth of microbes.
Explanation-
The common salt, sugar, oils, and spices provide a medium that resists the activity of microbes in the food.
The preservation of food by adding a sufficient amount of salt is called salting.
The salt prevents the water from being available for microbial growth.
It is used for the preservation of raw mango, amla, beans, meat, etc.
Hence, dehydration means the extraction of water (due to which concentration of water decreases and concentration of solutes in the food increases) from the food thereby preventing microbial growth.