Food preservation techniques is the method and some knowledge of the effects on nutrients. There are natural preservatives, and chemical processes such as dehydration, irradiation and vacuum packaging. A single goal for all these proposals, maintaining edibility and nutrient status of the food

Why are they food perishable?
Over time, the enzymes present in foods that digest the host cells and initiate their decomposition. Furthermore, most foods are rich in water and sugar, both of which promote the proliferation of micro-organisms (bacteria, fungi, yeasts, for example). Finally, the oxygen in the air can address food: fruit black and fats become rancid. Conservation aims several objectives, reduce the level of food water, neutralize the enzymes and micro-organisms and prevent the action of oxygen.

The three types of food preservation.
All foods have a limited shelf life. Industrial goods must display on their packaging with a use-by date. We distinguish between food conservation short, medium or long.

The short-preservation for perishable goods whose shelf life is between one and two weeks maximum, in the case of meat, sausages, milk and dairy products, eggs, cheese, fruit and vegetables. Most must be placed in refrigerator. Certain foods should be eaten the same day as fish, grated carrot and minced meat. Some may be frozen, allowing for longer storage.

The average retention for the fresh food can be stored in a cellar or storeroom, as some fruits and vegetables or salted and dried. It is imperative that the cellar is cool, dry and well ventilated. For potatoes, place of storage must be dark to prevent greening (related to the formation of solanine, a toxic substance) and germination.

Conservation-long case of dry foods, canned and frozen foods. Dry goods such as vegetables and fruits, pasta or rice are very resistant. Virtually insensitive to temperature, they remain a year or more. They must be placed to protect from moisture.

Cans are sterilized at a minimum temperature of 100 ° C in a container made of metal or glass. Their shelf life is at least one year. Canned glass should be stored away from light.