1. Washing the pulses and rice repeatedly may remove up to 40 per cent of the original water soluble B-vitamins such as thiamine and niacin. It may also result in loss of some materials present in them.
2. Vegetables and fruits should be washed before cutting or peeling. Washing of vegetables and fruits after they have been peeled, removes the water soluble vitamins such as vitamin B-complex and vitamin C.
3. Fruits and vegetables should be cut just before use. When cut fruits and vegetables are kept in the open for a long time, then the vitamin C present in them is oxidised by air.
4. Water used for cooking should not be thrown away after cooking because it contains some proteins and considerable amounts of water soluble vitamins and minerals. Use only adequate quantity of water during cooking.
5. Deep frying and heating for a long time or heating at a high temperature should be avoided during cooking. It food material are heated above 700 C for a long duration, proteins become hard and coagulated. In this form, they are not easily absorbed by the body. Thus, over cooking results in loss of precious nutrients. Hard boiled eggs and overcooked meat are relatively less nutritious.