The higher the storage heat, the worse the taste. That missing portion turned into 0.001 percent DKP and 53.5 parts per billion formaldehyde. In the sample from my room, all that was left of the 0.06 percent aspartame was 0.051 percent. The missing portion had turned into 0.002 percent DKP and 231 parts per billion formaldehyde. In the incubator sample, there was only 0.026 percent aspartame, but 0.010 percent DKP and 76.2 parts per billion formaldehyde.
Temperature creates two effects.
First, the higher the storage temperature, the higher the level of DKP in the soda. Second, room temperature seems to create the highest levels of formaldehyde in soda. At very high temperatures, the formaldehyde breaks down. However, even when refrigerated, the aspartame breaks down into formaldehyde. After diet soda containing aspartame is purchased, it should not be stored in the heat or under any conditions for a long period of time.