Kinetic behaviour of DPPH radical scavenging activity of tomato waste extracts

Abstract

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 > Bačka > 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).

Keywords

• tomato waste
• DPPH radicals
• free radical scavenger
• kinetic behaviour