Maillard reaction /maɪˈjɑː(ɹ)ɹiˈækʃən/ noun1 •The condensation reaction of an amino acid and a reducing sugar, followed by polymerization to form brown pigments - melanoidins; one of the causes of browning during cooking.If the surface temperature exceeds the boiling point, as it does during grilling and frying, the Maillard reactions produce typical roasted, browned aromas. — 2004 formsMaillard reactions