As shown in Fig 3D, FSW and USW extracts exhibited strong
hydroxyl radicals scavenging activity. For instance, at 0.24 mg/
ml, hydroxyl radicals scavenging effect of soy whey extracts
were above 90% regardless of the fermentation. Many studies
have reported that phenolics and isoflavones exhibit hydroxyl
radical scavenging activity (Chandrasekara & Shahidi,
2012; Singh et al., 2010). Chandrasekara and Shahidi (2012) reported
that phenolic compounds present in sample extracts
were effective ferrous ion chelating agents; hydroxyl radical
scavenging activity observed could be due to the direct scavenging
of hydroxyl radicals and/or chelating of ferrous ions
which are needed to generate hydroxyl radicals in the assay
system. Both FSW and USW extracts contained high amounts
of phenolics (Table 1), which were responsible for the strong
scavenging ability for hydroxyl radicals.