Canning is a method of preserving food in which the food contents are processed and sealed in an airtight container. Canning provides a typical shelf life ranging from one to five years, although under specific circumstances a freeze-dried canned product, such as canned, dried lentils, can last as long as 30 years in an edible state. In 1795 the French military offered a cash price of 12,000 francs for a new method to preserve food. Nicolas Appert suggested canning and the process was first proven in 1806 in test with the French navy and the prize awarded in 1809 or 1810. The packaging prevents microorganisms from entering and proliferating inside.