Abstract: Among the 20 proteinogenic amino acids, 19 can exist in two stereoisomeric forms, D- and L-enantiomers except glycine. According to conventional theory, L-amino acids are the main body involved in life activities, while little attention has been paid to the existence and physiological activity of D-amino acids in organisms. With the development of analytical technologies for chiral amino acids, a large number of D-amino acids and bioactive peptides containing D-amino acids have been found in various organisms, including mammals, plants, microorganisms and humans. D-amino acids possess unique physiological activities such as neural signal transduction, hormone regulation, antibacterial effect and immune regulation. Daily diet is an important source of D-amino acids for humans, and the daily average supply of D-amino acids for humans is about 100 mg. D-amino acids in foods mainly origin from processing conditions such as fermentation, high temperature and certain pH, along with a small amount from food raw materials. At present, emerging functional foods with D-amino acids as the major component have begun to appear in the market. D-amino acids hold great potential that deserves to be explored further and are expected to be an important ingredient for the development of new functional foods in the future.

Key words: D-amino acids; chiral amino acids; racemization; processing conditions; physiological functions; functional foods