Mother nature have blessed us with easy to get and use preservatives, which we can use with food still can avoid harmful effects of preservatives.
Natural Preservative: salt, sugar, honey, vegetable oil, alcohol, castor oil
Natural Preservation techniques: freezing, pickling, smoking and salting
Use of Salt as preservative: Salt cubes if placed in grains will save grains from insects. Salt cubes placed in chilly powder, turmeric powder, coriander powder, carom seeds and cumin seeds will save them from getting spoiled and maintain their fragrance and flavor.
Use of Salt and Sugar cyrup: Any food item if soaked in Salt or Sugar or Salt and Sugar cyrup and kept in freezer may last long. But vegetables like bittergourd will be soon distroyed if soaked in salt and kept for more than 5 minutes.
Use of Vegetable oil and Castor Oil: oiling food grains like wheat with castor oil will save wheat from getting spoiled. Oiling rice with vegetable oil will save rice from getting spoiled.
Other ways of Preservation: Mercury Tablets – a grayies color tablets of mercury could be placed in food grains like bengal gram, green gram, golden gram to save them from getting spoiled.
A powder made from shell material can be mixed with Black lentils and White lentils can save them from getting spoiled.
Above said are the most common and ancient techniques to preseve food. Apart from this books and clothes can be preserved from insects if adirachta indica’s dry leaf, whose taste is bitter is placed with books and clothes.