The usually quoted rule of thumb is that chemical reactions double their rate for each temperature increase of 10 °C (18 °F) because activation energy barriers are more easily surmounted at higher temperatures.However, as with many rules of thumb, there are many caveats and exceptions.There is a widespread impression, for instance in industry, that "triple time" can be simulated in practice by increasing the temperature by 15 °C (27 °F), e.g., storing a product for one month at 35 °C (95 °F) simulates three months at 20 °C (68 °F).
One major exception is the Shelf Life Extension Program (SLEP) of the U. Department of Defense (Do D), which commissioned a major study of drug efficacy from the FDA starting in the mid-1980s. The SLEP and FDA signed a memorandum that scientific data could not be shared with the public, public health departments, other government agencies, and drug manufacturers.
For example, an MRE field ration is designed to have a shelf life of three years at 80 °F (27 °C) and six months at 100 °F (38 °C).
Nearly all chemical reactions can occur at normal temperatures (although different reactions proceed at different rates).
This is important, as consumers enjoy fresher goods, and furthermore some stores can be fined for selling out of date products; most if not all would have to mark such products down as wasted, resulting in a financial loss.
Shelf life depends on the degradation mechanism of the specific product.
Shelf-life is not to be confused with service-life (defined as, A general term used to quantify the average or standard life expectancy of an item or equipment while in use.