1-Aminocyclopropane-1-carboxylic acid

The full chemical name of ACC, the immediate building block plants use to synthesise ethylene. Applied exogenously it functions as a plant growth regulator, nudging processes such as ripening, fruit thinning and flowering by feeding directly into the ethylene pathway. For food science its importance is mostly indirect but genuine: every ethylene-driven change in harvested fruit, from peel colour development to flesh softening, runs through this compound. It sits one enzymatic step upstream of ethylene itself, which is why postharvest physiologists treat ACC levels as an early warning of ripening to come.