Oxidative consequences of UV irradiation on isolated milk proteins: effects of hydrogen peroxide and bivalent metal ions

KIVATINITZ SILVIA CLARA

INTERNATIONAL DAIRY JOURNAL

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2016 vol. 55 p. 64 - 64

0958-6946

#946;-Casein (β-CN), β-lactoglobulin (β-LG), and α-lactalbumin (α-LA), were subjected to UV irradiation, alone or in the presence of hydrogen peroxide, hydrogen peroxide plus copper, or iron. Disappearance of tryptophan (Trp) was fastest for α-LA and slowest for β-CN. Hydrogen peroxide accelerated loss of Trp, while addition of iron did not further increase the speed of Trp reduction, but the addition of copper did. Oxidation products were higher for β-CN than for β-LG following UV irradiation alone or in the presence of hydrogen peroxide or hydrogen peroxide plus iron. In the presence of copper, oxidation rates were similar for both proteins. UV photo-oxidation caused the loss of the native polypeptides, the rate of this being faster for β-LG than for β-CN. These results are compatible with the concept that formation of dityrosine and N-formylkynurenine were favored by mobility in the native protein.