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Association of non‐starch polysaccharides and ferulic acid in grain amaranth ( Amaranthus caudatus L.) dietary fiber
Author(s) -
Bunzel Mirko,
Ralph John,
Steinhart Hans
Publication year - 2005
Publication title -
molecular nutrition and food research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.495
H-Index - 131
eISSN - 1613-4133
pISSN - 1613-4125
DOI - 10.1002/mnfr.200500030
Subject(s) - amaranth , ferulic acid , chemistry , chromatography , high performance liquid chromatography , hydrolysis , starch , polysaccharide , acid hydrolysis , biochemistry
Abstract The association of ferulic acid, an alkali‐extractable phenolic acid in amaranth ( Amaranthus caudatus L., Amaranthaceae) insoluble fiber ( trans ‐ferulic acid: 620 μg·g –1 , cis ‐ferulic acid: 203 μg·g –1 ), and non‐starch polysaccharides was investigated. Enzymatic hydrolysis of insoluble amaranth fiber released several feruloylated oligosaccharides that were separated using Sephadex LH‐20‐chromatography and reversed phase‐high performance liquid chromatography (RP‐HPLC). Three compounds were unambiguously identified: O‐ (6‐ O ‐ trans ‐feruloyl‐β‐ D ‐galactopyranosyl)‐(1→4)‐ D ‐galactopyranose, O‐ (2‐ O ‐ trans ‐feruloyl‐α‐ L ‐arabinofuranosyl)‐(1→5)‐ L ‐arabinofuranose, and O ‐α‐ L ‐arabinofuranosyl‐(1→3)‐ O‐ (2‐ O ‐ trans ‐feruloyl‐α‐ L ‐arabinofuranosyl)‐(1→5)‐ L ‐arabinofuranose. These feruloylated oligosaccharides show that ferulic acid is predominantly bound to pectic arabinans and galactans in amaranth insoluble fiber. 5‐ O ‐ trans ‐Feruloyl‐ L ‐arabinofuranose was the only compound isolated in pure form from an acid hydrolyzate. This compound may have its origin from pectic arabinans but also from arabinoxylans.