If you have to have the food to keep it long, one must avoid that bacteria and fungi can grow.
What do you do best by making sure that they thrive as poorly as possible. The more troublesome to make the lives of the bacteria, the longer keeps food out. one of the ways to do the bacteria's life a hassle is to preserve the food.
Preserving means really just to maintain, so to make the food more durable. This can be done in several different ways. The bacteria do not like:
Often, you use several ways at once