1.1DETERMNATIN OF AOA BY ANTIRADICAL ACTIVITY (DPPH):

Principle:
Determination of scavenging activity of the 1,1-diphenyl-2-picylhydrazyl (DPPH) free radical is a very fast method to evaluate the anti oxidant activity of the extract. When DPPH radical is scavenged by the anti oxidant activity through donation of hydrogen to form stable DPPH-H molecule, color changes from purple to yellow and this is monitored by measuring the decrease in optical absorbance at 517 nm.
Reagents:
DPPH reagent (1,1-diphenyl-2-picylhydrazyl)
Ascorbic acid (standard)
Methanol (100%)
Distilled water

Method:
DPPH*(2,2’-diphenyl-1-picrylhydrazyl) scavenging activity was determined using a modified method of Brand-Williams et al., 0.1 mM DPPH* was dissolved in 80% aqueous methanol 0.1 ml of the extracted sample was taken and 2.9 ml of the methanolic DPPH* solution was added and kept in the dark for 30 min and read at 517 nm. The standard sample is taken as µg equivalent ascorbic acid present in one gram of food sample. A standard graph was run with ascorbic acid and AOA of the samples, quantity of ascorbic acid and the optical absorbance at 517 nms. The total AOA of the foods are expressed in this thesis as mg ascorbic acid equivalent in 1 gm of the edible portion of that food stuff.