Pro-oxidant activities of carnosine, rutin and quercetin in a beef model system and their effects on the metmyoglobin-reducing activity

The effects of carnosine, rutin and quercetin on oxidative processes and metmyoglobin (MetMb)-reducing activity in a beef model system were investigated. Ground beef was mixed with antioxidant solution at two concentrations. Storage period and antioxidant treatment negatively affected colour, colour stability and thiobarbituric acid-reactive substances values. Carnosine, rutin and to lesser extent quercetin accelerated discolouration, accumulation of MetMb and lipid peroxidation in the meat. The results suggest that these antioxidants acted as a pro-oxidants under the specified experimental conditions. The pro-oxidant activities were in the following order: carnosine>rutin>quercetin. The MetMb-reducing activity was not correlated with storage time, colour parameters, MetMb (%) or lipid oxidation. The MetMb-reducing activity was significantly reduced by 1 mM carnosine. However, there was no association between MetMb-reducing activity and colour stability during post-mortem storage.