The result of the food handling process is preserved in such a way as to avoid or slow down its deterioration (loss of quality, edibility or nutritional values). This is usually achieved by preventing the growth of natural grass, yeasts, fungi and other microorganisms, as well as delaying the oxidation of fats that cause rancidity.

Canning also includes processes that inhibit the natural discoloration that can occur during food preparation, such as the enzymatic browning reaction that occurs after cutting. Many canning methods include various food preservation techniques. Canned fruits, for example making jams from them, involve cooking (to reduce their humidity and kill bacteria, fungi, etc.), sugaring (to prevent them from growing again) and packaging in an airtight jar (to avoid contamination ).

It is important aspects of canning to maintain or improve nutritional values, texture and flavor, although historically some methods have drastically altered the character of preserved foods.