High methoxyl pectin grafted onto gallic acid by one- and two-pot redox-pair procedures.

The aim of this research was to graft gallic acid (GA) onto high methoxyl pectin (HMP) through the redox-pair of ascorbic acid (Aa) and hydrogen peroxide (H 2 O 2) with one- and two-pot procedures. The effectiveness of the both procedures and the chemical, physical and antioxidant properties of the obtained HMP-GA were evaluated. HMP-GA one-pot (23.3 ± 0.21 mg GA Equivalent (GAE)/g) and HMP-GA two-pot (32.3 ± 0.52 mg GAE/g) were best obtained at H 2 O 2 /Aa molar ratio-HMP/GA weight ratio of 9.0–0.5 and 16.0–0.5, respectively. The UV–Vis and FT-IR spectra and along with their derivative and thermal gravimetric analyses, revealed differences between HMP-GA one-pot and HMP-GA two-pot. The latter exhibited a greater antioxidant capacity than the former in single electron transfer (ET), hydrogen atom transfer (HAT), and ET-HAT mixed assays. The chemical differences can be attributed to side reactions that may have interfered with the grafting reaction. Consequently, HMP-GA, possessing unique antioxidant and prebiotic properties, can be synthesized through redox-pair procedures. [Display omitted] • High methoxyl pectin (HMP) grafted to gallic acid (GA) by redox-pair procedures. • Two-pot redox-pair procedure showed higher grafting ratio than one-pot procedure. • HMP-GA one-pot and HMP-GA two-pot showed differences in UV–Vis, FT-IR spectra. • HMP-GA one-pot and HMP-GA two-pot showed differences in thermal gravimetric analysis. • HMP-GA two-pot exhibited a greater antioxidant capacity than HMP-GA one-pot. [ABSTRACT FROM AUTHOR]