Enhancement of anti-radical activity of pectin from apple pomace by hydroxamation

Apple pomace was utilized to extract pectin of which structure was modified by hydroxamation to improve its antioxidant effect. As the pectin obtained from apple pomace was treated with alkaline hydroxylamine for 4–48 h, the hydroxamic acid content of the pectin derivative increased from 2.68 to 10.43%. Compared to native pectin, the FT-IR spectra of the derivative showed two new absorption bands at 1646 cm−1 (Cdouble bond; length as m-dashO) and 1568 cm−1 (N–H), confirming that the hydroxamic acid derivative from apple pomace pectin was successfully obtained. The pectin derivatives were also shown to have enhanced anti-radical activities against DPPH in a dose-dependent way. Moreover, the hydroxamation improved the scavenging effect of the pectin which was even 3-fold higher than that of the native one. Thus, the introduction of hydroxamic acid into the pectin structure seemed to be a useful tool for improving biological activities of pectins.