Food-borne melanoidin based peroxidase mimic for the precise detection of total antioxidant capacity

Drawing on the structure of the natural horseradish peroxidase (HRP) active site, in this study, food-borne Melanoidin and Fe 3+ were used to construct a peroxide mimic enzyme, which possessed excellent peroxidase (POD)-like activity with the Km values of 0.088 mM and 0.358 mM toward 3,3′,5,5′-tetramethylbenzidine (TMB) and hydrogen peroxide (H 2 O 2 ), respectively. Given the good POD-like activity of Melanoidin/Fe 3+ , a convenient, selective, and sensitive method for the determination of ascorbic acid (AA) was defined. The method covered the 10–100 μM AA concentration range with a 1.19 μM detection limit. With favorable anti-interference and strong stability, Melanoidin/Fe 3+ was successfully applied to the determination of AA in foods and medicines. The high activity of Melanoidin/Fe 3+ provides a new strategy for designing high-performance nanozymes, which has great potential in exogenous dietary and healthcare applications.