I have been storing food for 45 years and by following four simple rules have lost very little. The only foods I have lost have been commercially canned products that failed to be rotated in a timely manner. In my family we have wheat stored that is over forty years old and is still quite usable.
The rules of food storage are summed up by the acronym HALT. It stands for the four enemies of good food storage. These are humidity, air (oxygen), light and temperature.
Humidity or moisture will damage or destroy almost any foods over time. Wheat and grains that are stored should be low moisture. In the case of wheat, it should contain less than 10% moisture. Home-dehydrated foods for long-term storage should be dried until they are brittle in most cases. Metal cans should be protected from moisture to prevent rust. Store your foods in a dry area and if they are in your garage or basement do not store them directly on or against concrete.
Air or oxygen, Protecting your food from oxygen, prevents the growth of aerobic pathogens and spoilage organisms, including molds. The lack of oxygen protects dry foods from insect damage and help preserve product quality. Use metal, glass or Mylar bags to protect your food, plastic does not protect your food from oxygen, plastic breathes.
Light can cause vitamin loss and undesirable changes in color, proteins, and fats or oils. Fat soluble vitamins, such as A, D and E are particularly sensitive to damage from light.
Temperature or heat. Exposure to high temperatures will shorten the shelf life of your foods and cause vitamin and flavor loss. Storing items in cooler areas at temperatures between 40-60F will extend the shelf life of your foods and reduce nutrient loss over time.
Just following these rules and regularly rotating foods as needed, will prevent the loss of expensive foods and give you the best quality products.