Understanding why food spoils is critical when considering the best way to preserve it. The most common reason food spoilage occurs is because it is exposed to mold and bacteria, causing pathogens to attack. Controlled-atmosphere storage is one of the most important innovations in fruit and vegetable storage systems, as the composition of gas in the storage affects their storage life. Carbon dioxide (CO₂) is most commonly used to prevent the growth of mold and bacteria and is used to achieve the longer shelf life.