Write the methods of food preservation

Food Preservation
Chemical Method
Sodium benzoate and sodium metabisulphite are common preservatives. These are also used in the jams and squashes to check their spoilage.
Preservation by Common Salt
Salting is also used to preserve Alma, raw mangoes, tamarind,
Preservation by Sugar
Jams, jellies and squashes are preserved by sugar.
Preservation by Oil and Vinegar
Use of oil and vinegar prevents spoilage of pickles
Heat and Cold Treatments
Boiling kills many microorganisms. Low temperature inhibits the growth of microbes. Storage and Packing