Quinoa (Chenopodium quinoa W.) and amaranth (Amaranthus caudatus L.) provide dietary fibres high in pectic substances and xyloglucans

Characterization of diferuloylated pectic polysaccharides from quinoa (Chenopodium quinoa WILLD.)

In plants belonging to the order of Caryophyllales, pectic neutral side chains can be substituted with ferulic acid. The ability of ferulic acid to form intra- and/or intermolecular polysaccharide cross-links by dimerization was shown by the isolation and characterization of diferulic acid oligosaccharides from monocotyledonous plants. In this study, two diferulic acid oligosaccharides were isolated from the enzymatic hydrolyzate of seeds of the dicotyledonous pseudocereal quinoa by gel permeation chromatography and preparative HPLC and unambiguously identified by LC-MS(2) and 1D/2D NMR spectroscopy. The isolated oligosaccharides are comprised of 5-5- and 8-O-4-diferulic acid linked to the O2-position of the nonreducing residue of two (1→5)-linked arabinobioses. To get insight into the structure and the degree of phenolic acid substitution of the diferuloylated polysaccharides, polymeric sugar composition, glycosidic linkages, and polysaccharide-bound monomeric phenolic acids and diferulic acids were analyzed. This study demonstrates that diferulic acids are involved into intramolecular and/or intermolecular cross-linking of arabinan chains and may have a major impact on cell wall architecture of quinoa and other dicotyledonous plants of the order of Caryophyllales.

Innovations in Health Value and Functional Food Development of Quinoa (Chenopodium quinoa Willd.)

Quinoa (Chenopodium quinoa Willd., Amaranthaceae) is a grain-like, stress-tolerant food crop that has provided subsistence, nutrition, and medicine for Andean indigenous cultures for thousands of years. Quinoa contains a high content of health-beneficial phytochemicals, including amino acids, fiber, polyunsaturated fatty acids, vitamins, minerals, saponins, phytosterols, phytoecdysteroids, phenolics, betalains, and glycine betaine. Over the past 2 decades, numerous food and nutraceutical products and processes have been developed from quinoa. Furthermore, 4 clinical studies have demonstrated that quinoa supplementation exerts significant, positive effects on metabolic, cardiovascular, and gastrointestinal health in humans. However, vast challenges and opportunities remain within the scientific, agricultural, and development sectors to optimize quinoa's role in the promotion of global human health and nutrition.

Neutral Pectin side chains of Amaranth (Amaranthus hypochondriacus) contain long, partially branched Arabinans and short galactans, both with terminal arabinopyranoses

Amaranth is a pseudocereal of high nutritional value, including a high dietary fiber content. Amaranth dietary fiber was suggested to contain large amounts of neutral rhamnogalacturonan I side chains. In this study, endo-arabinanase and endo-galactanase were used to liberate arabinan and galactan oligosaccharides from amaranth fiber. The liberated oligosaccharides were identified by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and HPLC-MS(n) using standard compounds, which were isolated from amaranth, sugar beet, potato, and red clover sprouts and characterized by one- and two-dimensional NMR spectroscopy. It was demonstrated that insoluble amaranth arabinans have linear and branched areas, with the O-3 position being the dominant branching point. Minor amounts of branches at position O-2 and double substitution were also found. Amaranth arabinans were also demonstrated to contain terminal α-(1→5)-linked l-arabinopyranose units. In addition, it was evidenced that galactans from amaranth seeds are composed of β-(1→4)-linked d-galactopyranose units, which can also be terminated with l-arabinopyranose units. In direct comparison to structural elucidation of amaranth fiber by using methylation analysis, the advantage of the enzymatic approach over methylation analysis was demonstrated.