The kinetic behaviour of tomato waste extracts (obtained from six genotypes)
and standard antioxidant compounds (ascorbic and caffeic acid) were
investigated using 2,2-diphenyl-1-picrylhydrazyl radical test. Based on the
time needed for the reaction to reach steady state, the investigated extracts
show very slow (steady state ? 180 min) antiradical behaviour, ascorbic acid
act as rapid antioxidant (steady state < 5min) while caffeic acid is
rapidintermediate antioxidant (5 min < steady state < 20 min). The efficient
concentrations at different kinetic times EC50,t were determined for all
extracts, ascorbic and caffeic acid. EC50,t was used as a parameter to screen
and compare antiradical activities of food extracts with slow kinetic action.
Irrespective of the time considered, the comparison of the EC50,t for
extracts showed that the DPPH radicals scavenging activity of extracts
decreased in the order of O2 > Knjaz > Backa > Saint Pierre > Rutgers >
Novosadski niski. Tomato waste extracts showed very slow kinetic action,
which is probably result of the different kinetic bevaviour of phenolic
compounds, present in tomato waste, as well as other antioxidants (vitamins,
carotenoids etc).