LAUSR

BACKGROUND The nixtamalization process improves maize's nutritional and technological properties. This process generates nixtamalized maize bran as a by-product which is a source of arabinoxylans (AX). AX are polysaccharides constituted of a xylose backbone with mono or di-arabinose substitutions, which can be ester-linked to ferulic acid (FA). The present study investigated the fine structural features and antioxidant capacity (AC) of nixtamalized maize bran arabinoxylans (MBAX) to comprehend the structure-radical scavenging capacity relationship in this polysaccharide deeply. RESULTS MBAX presented a molecular weight, intrinsic viscosity, and hydrodynamic radius of 674 kDa, 1.8 dL g-1 , and 24.6 nm, respectively. The arabinose to xylose ratio (A/X) and FA content were 0.74 and 0.25 g kg-1 polysaccharide, respectively. MBAX contained dimers (di-FA) and trimer (tri-FA) of FA (0.14 and 0.07 g kg-1 polysaccharide, respectively). The main di-FA isomer was the 8-5' structure (80%). Fourier transform infrared spectrum confirmed MBAX molecular identity, and the second derivate of the spectral data revealed a band at 958 cm-1 related to the presence of arabinose di substitution. 1H Nuclear magnetic resonance (NMR) spectroscopy showed mono and di-arabinose substitution in the xylan backbone with more monosubstituted residues. MBAX registered an AC of 25 and 20 μmol Trolox equivalent (TE) g-1 polysaccharide despite a low FA content, using ABTS (2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid) and DPPH (1,1-diphenyl-2-picrylhydrazyl) methods, respectively. CONCLUSION AC in MBAX could be related to the high A/X ratio (mainly mono substitution) and the high 8-5' di-FA proportion in this polysaccharide. This article is protected by copyright. All rights reserved.