DPPH radical scavenging capacity of yogurt
The free radical scavenging activity (RSA) of the extracts was
determined according to the procedure reported by von Gadow,
Joubert, and Hansmann (1997) using the stable 2,2-diphenyl-1-
picrylhydrazyl radical (DPPH). Briefly, 75 mL of sample extract
was added to 3 mL of a 6.1 105 M DPPH methanol solution and
incubated for 1 h at room temperature in the dark. After this time
and after a centrifugation step (16800 g, 10 min, 20 C), the
decrease in absorbance at 515 nm was recorded against methanol
as a control; a methanol solution of DPPH was used as a blank. The
inhibition percentage (IP) of the DPPH by the antioxidant extracts
was calculated according the formula
IP ¼ ½ðA0 min A60 minÞ=A0 min 100
where A0min is the absorbance of the blank at t ¼ 0 min and A60 min
is the absorbance of the samples at 60 min. The results were
expressed as mM Trolox equivalents (TE) per gram of sample by
means of a doseeresponse curve for Trolox (0e350 mM).