Here's a good link on food storage questions:

http://learntoprepare.com/2011/11/food-storage-packing-do-it-yourself-facts-myths-revisited/

Even packaged, some food items don't last a long time in storage, such as powdered milk, fats, oils, etc. White rice, unground wheat etc do last quite a while.

One thing I've been trying is using mason jars, packaging the product, and then adding an oxygen absorber, which does seal the jar (eliminates the oxygen leaving a nitrogen atmosphere inside the jar.)

tim