The USU Cooperative Extension System only provides science-based recommendations. That means that all of our recommendations are backed with sound science. In some cases processes are proven safe using science and are recommended. If processes are not proven safe, not researched, or lack quality scientific data we will not recommend them.
There are two separate issues to consider as foods age: food safety and food quality.
Food Safety: Foodborne illness can come from three sources: physical, chemical, and biological. The biological hazards include all of the microorganisms that cause foodborne disease, including botulism. Chemcial hazards include non-food grade containers, cleaners, and pesticides. Lastly, the physical hazards include things like stones or rocks.
Food Quality: Foods naturally deteriorate as they age. The science of food storage and preservation has evolved from our attempts to slow that deterioration. The prime concern with shelf life quality of foods is preventing spoilage microorganisms from growing. This is done through food preservation methods (drying, canning, etc.). Oxygen is the next factor. Oxygen catalyzes chemcial reactions that lead to rancidity. Removing oxygen in most cases will extend the qulaity shelf life of foods. However, great caution must be used when removing oxygen from food environments, since this creates the perfect growth environment for botulism-causing bacteria to grow.