Antioxidant activity of SPF, as affected by simulated gastrointestinal pH conditions, is presented in Figure 1. All five antioxidant assays conducted, concurred that the antioxidant activity of treated SPF was significantly higher (p < 0.05) than non-treated SPF. It was found that treated SPF exhibited relatively high 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·) scavenging activity, which is approximately four times the activity shown by non-treated SPF. Correspondingly, 2,2'-azino-bis(3-
ethylbenzthiazoline-6-sulphonic acid) radical cation (ABTS·+) scavenging activity and ferric reducing antioxidant power (FRAP) assays also showed that treated SPF displayed higher activities (approximately three times higher) than non-treated sample. Treated SPF was also capable of retarding linoleic acid peroxidation eight times more efficiently than non-treated SPF, as indicated through the use of β-carotene-linoleate model system. In the iron chelating assay, treated SPF exhibited chelating capacity
eight times higher than non-treated SPF.