Retrogradation?

A urea starch is a gelatinized starch created by adding urea to a starch to promote the starch's gelatinization at room tempertature. Suspensions of starch in urea solutions did not show any fermentation and retrogradation during 8 weeks storage, unlike ungelatinized starches.

Amylopectin is a branched-chain polymer of glucose that is a component of starch, characterized by frequent branching points that create a highly branched structure. It can be broken down into glucose units for energy more quickly than amylose due to its branched structure. Amylopectin is less prone to retrogradation compared to amylose, making it more suitable for applications where a gel-like consistency is desired.

Food will decay if bacteria or fungi is on the food because fungi and bacteria are living organisms so they eat at the flesh of the food which cause the fungi to spread or cause the bacteria to multiply which eventually will cause the food to eventually be 100% decomposed.