According to Figs. 3 and 4, both DPPH radical-
scavenging activity and the inhibition of deoxyribose degradation
increase with the concentration of phenolic substances.
Therefore, due to the presence of higher phenolic content per unit
mass of oil, higher phenolic-dependent antioxidant capacities can
be expected for HECO, compared with CECO. Studies have shown
that the DPPH radical-scavenging activity and the inhibition of
deoxyribose degradation rapidly increase with the total phenol
concentration or antioxidant concentration initially and then slow
down when the antioxidant activities are close to maximum values
(Chung, Chang, Chao, Lin, & Chou, 2002; Kaur, Arora, & Singh,
2008). In Fig. 3, the CECO response reaches close to the maximum
value at 50 mg/l and thereafter, further increase of the total phenol
concentration improves the CECO response only moderately. Similarly,
the HECO response in Fig. 4 reaches close to the maximumcentration beyond this value improves the HECO response only
moderately.
value around 25 mg/ml and the increase of the total phenol con