Abstract: The purpose of this study was to investigate the Maillard reaction between snapper fish scale peptides (FSP) and xylose (Xyl) as a function of reaction time, mass ratio of Xyl to FSP, total concentration of Xyl and FSP, initial pH and temperature and to characterize the structure and properties of Maillard reaction products prepared from a mixture of Xyl and FSP (1.3:1, total concentration of 78 mg/mL, at initial pH 11.85) at 100 ℃ for 4.05 h. The changes in fluorescent intensity, Fourier transform infrared spectra, free amino group content and Tricine-SDS-PAGE with periodic acid Schiff staining suggested that covalent crosslinking between FSP and Xyl occurred, the structure of FSP was changed and new compounds were formed through Maillard reaction. 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, 2,2’-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt radical (ABTS+·) scavenging, hydroxyl radical scavenging and reducing power assays suggested that the antioxidant activity of FSP was significantly improved via Maillard reaction (P < 0.05). The Maillard reaction products inhibited polyphenol oxidase activity with IC50 value of 0.54 mg/mL. The underlying mechanism may be attributed to their Cu2+-chelating activity and the chelating sites may be related to antioxidant groups.

Key words: snapper fish scale (FSP), Maillard reaction, antioxidant activities, inhibitory activity against polyphenol oxidase, Cu2+ chelating activity