Fine structural features and antioxidant capacity of ferulated arabinoxylans extracted from nixtamalized maize bran.

Background: The nixtamalization process improves the nutritional and technological properties of maize. 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 , and 24.6 nm, respectively. The arabinose-to-xylose ratio (A/X) and FA content were 0.74 and 0.25 g kg polysaccharide, respectively. MBAX contained dimers (di-FA) and trimer (tri-FA) of FA (0.14 and 0.07 g kg polysaccharide, respectively). The main di-FA isomer was the 8-5' structure (80%). Fourier transform infrared spectroscopy confirmed MBAX molecular identity, and the second derivate of the spectral data revealed a band at 958 cm related to the presence of arabinose disubstitution. H-Nuclear magnetic resonance 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 equivalents g polysaccharide despite a low FA content, using ABTS (2,2'-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid) and DPPH (1,1-diphenyl-2-picrylhydrazyl) methods, respectively.

Conclusion: AC in MBAX could be related to the high A/X ratio (mainly monosubstitution) and the high 8-5' di-FA proportion in this polysaccharide. © 2023 Society of Chemical Industry.