Dehydroacetic Acid (E265) and its sodium salt Sodium Dehydroacetate (E266) are cyclic beta-keto acids that exert antimicrobial activity through inhibition of SH-containing enzymes and disruption of oxidative phosphorylation in microbial cells. DHA itself has low water solubility (0.1 g/100 mL at 20°C), while the sodium salt is highly water-soluble, making the latter more common in food applications.
Dehydroacetic Acid is approved in the EU as E265 under Regulation 1333/2008 and is used in some Asian markets for food preservation, particularly in strawberry and other surface-application contexts. It is also widely used in cosmetics and personal care products as a preservative at up to 0.6%. JECFA and various regulatory bodies have established acceptable daily intake limits.