Adipic acid is a white crystalline solid and a straight-chain aliphatic dicarboxylic acid. It is primarily used in the production of nylon-6,6, where it reacts with hexamethylenediamine. Traditionally derived from petrochemical sources, adipic acid is increasingly being synthesized from renewable substrates using biotechnological methods. It also serves as a key ingredient in the manufacture of plasticizers, polyesters, and polyurethanes. In food applications, adipic acid functions as an acidulant, offering a smooth, tart taste and excellent buffering capacity, especially in dry powdered mixes. It is practically non-hygroscopic, has a melting point of 151–154°C, and is soluble in water at moderate levels