The information collected here comes from the USDA, Brigham Young University's Department of Nutrition, Dietetics and Food Science, the Utah State University Cooperative Extension, and the Church of Latter Day Saints website on 'provident living'. Those crazy Mormons, they're really into food storage, and they're nice enough to share their knowledge with Pagans like me. I also learned quite a lot from a professor in the Food Science Department at Utah State, whom I contacted with some questions and who was very patient and helpful.
Long-term emergency storage foods are meant to keep you alive if you had almost nothing else to eat. That means water, wheat and other grains, legumes, salt, honey or sugar, powdered milk, baking soda and cooking oil.
Sugar or Honey: 30kg (66 lbs)
Salt: 4.5kg (10 lbs)
Dry Beans: 36kg (80 lbs)
Powdered Milk: 27kg (60 lbs)
Olive Oil: 10 liters ("extra virgin", i.e. unrefined. Shelf-life of about 2 years) and/or
Probably the most effective and still practical long-term food-storage packaging method is with oxygen absorbers and metallized plastic (Mylar) pouches.
Another thing that might be handy to know about PETE bottles is that they can be used for solar water disinfection by ultraviolet radiation. It's as simple as filling them with water and setting them out in the sun for a few hours. Not even glass can be used for that, since although it's transparent to visible light, it's opaque to ultraviolet radiation.
Shelf life is one thing, palatability is another. Thirty-year-old food could keep you alive, but you might have to be some kind of hungry to eat it. According to the aforementioned professor, properly packaged dry foods will remain nutritionally stable (except for vitamins) for "dozens of years", but begin to be unpleasant to eat after about the decade mark.
Our current tentative plan is to store salt, sugar and baking soda in PETE bottles without oxygen absorbers. They should last, for our purposes, forever.
Wheat does not need to be stored in a low-oxygen environment, but a couple weeks of such an atmosphere will ensure that no bugs are present. We store it in PETE bottles with oxygen absorbers. ("Hawaiian Punch" gallon bottles are our favorite containers. We don't drink it, but the folks at our local recycling center save them for us.)
Everything else is probably best in Mylar pouches with oxygen absorbers.
We also stock up on necessities that require high technology and have a long shelf-life, like razor blades, medicines, soap, shampoo, paper towels, toilet paper, etc.
After about ten years, we plan on using our stores - converting them to fresh eggs by feeding them to our chickens if nothing else - and replenishing them with fresh stock.