Cooling, freezing, fermentation, sun-drying, etc., are few age-old food preservation techniques. With the advent of technology, modern methods of food preservation were developed. Chemicals and other natural substances were used for preservation. These substances are known as preservatives.
Adding preservatives is the chemical method of food preservation. Conventional antimicrobial preservatives include calcium propionate, sodium nitrite, sodium nitrate, sulphites (sulfur dioxidepotassium hydrogen sulfite, sodium bisulfite, etc.) and disodium EDTA. BHA and BHT are antioxidants.