Abstract: Maillard reaction products (MRPs) were prepared by heating casein, soy protein isolate and reducing sugars (glucose and lactose). The reducing power, inhibition against autooxidation of lecithin liposome system, radical (·OH and DPPH·) scavenging effect of the MRPs were investigated by the spectrometer. The results indicated that the MRPs of casein and reducing sugar possess higher reducing power, DPPH· radical scavenging activity, inhibition against autooxidation of lecithin liposome system than those of MRPs prepared from soy protein and reducing sugar. The antioxidant capacities are related to concentrations of MRPs and reaction time. The reducing power, ·OH and DPPH· radical scavenging activities of MRPs of casein and reducing sugar increase with reaction time prolonging. Whereas the inhibition rate against autooxidation of lecithin liposome system inereases at first and then decreases. At the same reactant concentration the antioxidant capacities of MRPs increase with heating time prolonging.

Key words: soy protein isolate, casein, reducing sugar, Maillard reaction products, antioxidant ability, radical scavenging