Glycolic acid is a colourless, hygroscopic acid occurring as a constituent of cane sugar juices and unripe grapes, and a chemical intermediate of the conversion of glycine to ethanolamine. It is the smallest alpha-hydroxy acid. While famous in cosmetics for exfoliation, in food contexts it appears as a natural fruit acid and as a building block of biodegradable packaging polymers such as polyglycolic acid. Its strong acidity means direct food additive use is limited compared with citric or malic acids, but its natural occurrence makes it a normal minor component of plant-derived foods.