Search

Laboratory produced DDGS samples were compared with commercial samples from a distillery and a biofuel plant. Changes in structure, solubility and content of arabinoxylan (AX) was determined. The distillation process results in a relative increase of AX content compared to the starting material. The heating and drying processes involved in the production of DDGS lead to an increased solubility and viscosity of water-extractable AX. Production of DDGS results in structural changes to the AX. There is a decrease in 2- and 3-linked arabinose oligosaccharides, that contributes to around a 50% reduction in arabinosylation in DDGS compared with the starting grains. The current study shows that laboratory-scale DDGS provide an accurate representation of the commercial scale and that the AX composition of DDGS is consistently uniform irrespective of starting material. The uniformity of DDGS and thin stillage makes them a good potential source of AX for production of prebiotics or other novel products. [ABSTRACT FROM AUTHOR]

The study was carried out to investigate the effect of hyperthermophilic xylanase B (XynB) from Thermotoga maritima on the properties of wheat bread and its staling during storage. The presence of XynB in the dough led to improvements in the breadmaking quality (i.e. specific volume and crumb structure) and provided an anti-staling effect on breads compared to the control. Addition of XynB could cause ≈60% increase in specific volume in comparison with the control. By fitting the crumb firming kinetics during storage to the Avrami equation, it showed that XynB retarded the bread staling by reducing the initial crumb firmness and the firming process during storage. XynB hydrolyzed the isolated WU-AX faster than WE-AX under the ratio of wheat AX in wheat flour. Improvement of bread quality by XynB can partly be ascribed to the enzyme specificity. [Copyright &y& Elsevier]

The levels of xylanolytic activities ((1→4)-β-endoxylanases, β-d-xylosidases and α-l-arabinofuranosidases) and the levels of water extractable arabinoxylans (WEAX) in hot water extracts of malts were compared during malting of four barley cultivars of differing quality. Endoxylanase activity increased from day 1 after steeping showing a slight lag compared with the development of (1→3,1→4)-β-glucanase activity. The levels of endoxylanase activity were different between the cultivars. For example, at day 4, which would be a suitable endpoint for malting of good quality cultivars, total endoxylanase activities of Static and Chariot malts were twice that of Hart and Optic. This variation in level of endoxylanase between cultivars did not correlate with the content of water extractable arabinoxylans in hot water extracts of the malts. However, those cultivars that accumulated most water extractable arabinoxylan had a different set of endoxylanase isoforms. This suggests that expression of specific endoxylanase isoforms may influence the extent of arabinoxylan solubilisation and/or degradation.The β-xylosidases and α-arabinosidases increased from low levels after steep to a plateau of activity at day 6 or 7 of germination. Total xylosidase was always higher than the arabinosidase activity. There were differences between cultivars but these were small compared with the variation in endoxylanase activity. (1→4)-β-d-Endomannanase activity was detected in all four cultivars at 2 days germination then rose to a maximum around 5 days. [Copyright &y& Elsevier]

Destarched, deproteinised wheat bran contains ca 40% of water-unextractable arabinoxylan (WU-AX) which is solubilised more effectively by Bacillus subtilis endoxylanase (EC 3.2.1.8, XBS, ca. 41% of WU-AX) than by Aspergillus aculeatus endoxylanase (XAA, ca. 18%). While XBS preferentially converts WU-AX into enzymically solubilised arabinoxylan (ES-AX), XAA preferentially degrades water-extractable arabinoxylan and ES-AX. Arabinose to xylose ratios of ES-AX, released by XBS, decreased with increasing enzyme levels indicating an unexpected difference in their enzymic solubilisation which may be due to close packing of AX with low degree of substitution and/or limited solubility of the hydrolysed fragments. Wheat bran ES-AX released at low XBS concentrations had a higher relative peak molecular mass than those released at higher XBS concentrations. ES-AX invariably was of low relative molecular mass for all XAA concentrations tested. The results indicate that XBS is useful for the conversion of insoluble fibre to soluble fibre. [Copyright &y& Elsevier]

Representatives of three types of feruloyl esterases were examined for their ability to release mono- and di-meric ferulic acid from water-extractable and water-unextractable cereal cell wall material, either alone or in the presence of a family 10 or family 11 xylanase. A type-C feruloyl esterase from Talaromyces stipitatus (TsFaeC) released 100% of the ferulic acid from water-extractable wheat endosperm arabinoxylan when acting in combination with a xylanase from Trichoderma longibrachiatum. The type-A esterase from Aspergillus niger, AnFaeA, was most effective in releasing ferulic acid from wheat bran and brewers'' spent grain, with over 50% of the available ferulic acid being released from wheat bran in the presence of a xylanase from Bacillus subtilis. In general, family 11 xylanases were the preferred synergistic partners with feruloyl esterases for the release of ferulic acid, while family 10 xylanases were preferred for the liberation of diferulic acid, with only the 5,5′ form being released by the action of AnFaeA alone. This suggests that ferulic acid may be located in regions of low substitution on arabinoxylans while the 5,5′ diferulate moiety is located in more branched regions of the xylan chain. [Copyright &y& Elsevier]

There is a knowledge gap regarding the factors that impede the ruminal digestion of plant cell walls or if rumen microbiota possess the functional activities to overcome these constraints. Innovative experimental methods were adopted to provide a high-resolution understanding of plant cell wall chemistries, identify higher-order structures that resist microbial digestion, and determine how they interact with the functional activities of the rumen microbiota. We characterized the total tract indigestible residue (TTIR) from cattle fed a low-quality straw diet using two comparative glycomic approaches: ELISA-based glycome profiling and total cell wall glycosidic linkage analysis. We successfully detected numerous and diverse cell wall glycan epitopes in barley straw (BS) and TTIR and determined their relative abundance pre- and post-total tract digestion. Of these, xyloglucans and heteroxylans were of higher abundance in TTIR. To determine if the rumen microbiota can further saccharify the residual plant polysaccharides within TTIR, rumen microbiota from cattle fed a diet containing BS were incubated with BS and TTIR ex vivo in batch cultures. Transcripts coding for carbohydrate-active enzymes (CAZymes) were identified and characterized for their contribution to cell wall digestion based on glycomic analyses, comparative gene expression profiles, and associated CAZyme families. High-resolution phylogenetic fingerprinting of these sequences encoded CAZymes with activities predicted to cleave the primary linkages within heteroxylan and arabinan. This experimental platform provides unprecedented precision in the understanding of forage structure and digestibility, which can be extended to other feed-host systems and inform next-generation solutions to improve the performance of ruminants fed low-quality forages., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 Published by Elsevier B.V. on behalf of Research Network of Computational and Structural Biotechnology.)

Apart from its role as a digestive and absorptive organ, the gastrointestinal (GI) tract is a vital immune organ that encompasses roughly 70 % of the total immune cells of the body. As such, the physical, chemical and nutrient composition of the diet influences overall GI function, effectively as an immune organ. With the improvement in feed technology, agro-industrial co-products that are high in fibre have been widely used as a feed ingredient in the diets of pigs and poultry. Arabinoxylan (AX) and mannan are the most abundant hemicellulosic polysaccharides present in cereal grain and co-product ingredients used in the livestock industry. When monogastric animals consume diets containing high amounts of AX and mannans, stimulation of GI immune cells may occur. This involves the activation of several cellular and molecular pathways of the immune system and requires a considerable amount of energy and nutrients to be expended by the animal, which may ultimately influence overall health and growth performance of animals. Therefore, a better understanding of the role of AX and mannan in immune modulation will be helpful in modulating untoward GI immune responses, thereby minimising nutrient and energy expenditure toward this effort. This review will summarise pertinent research on the role of oligosaccharides and polysaccharides containing AX and mannans in immune modulation in order to preserve gut integrity., (© The Author(s) 2020.)

The starchy endosperm of the mature wheat grain comprises three major cell types, namely sub-aleurone cells, prismatic cells and central cells, which differ in their contents of functional components: gluten proteins, starch, cell wall polysaccharides (dietary fibre) and lipids. Gradients are established during grain development but may be modified during grain maturation and are affected by plant nutrition, particularly nitrogen application, and environmental factors. Although the molecular controls of their formation are unknown, the high content of protein and low content of starch of sub-aleurone cells, compared to the other starchy endosperm cells types, may result from differences in developmental programming related to the cells having a separate origin (from anticlinal division of the aleurone cells). The gradients within the grain may be reflected in differences in the compositions of mill streams, particularly those streams enriched in the central and outer cells of the starchy endosperm, respectively, allowing the production of specialist flours for specific end uses., (© 2019 The Authors.)

A liquid chromatography-MS (LC-MS) metabolomics analysis of plasma from portal-arterial catheterised pigs fed breads prepared with whole-grain rye or wheat flour with added concentrated arabinoxylan (AX) or β-glucan (BG) was conducted. Comparison of the effects of concentrated fibres with whole grains has received little attention. Six female catheterised pigs were given two white wheat breads with wheat AX or oat BG, two rye breads with ground rye (GR) or intact rye kernels (RK), and a control white wheat bread (WF) on separate occasions in a randomised cross-over design. The amount of available carbohydrate was similar for the five breads but varied in the content of protein. Plasma was collected continuously for 4 h after feeding. Glucose levels in the portal vein were reduced postprandially in response to the AX, GR and RK breads that had high contents of AX compared with WF bread (P < 0·03). AX and RK breads further tended to decrease plasma levels of some lysophosphatidylcholine species (P ≤ 0·10). The abundance of amino acids in plasma correlated with the protein contents in the breads and leucine uptake significantly affected insulin secretion in the mesenteric artery. In conclusion, the present study revealed that concentrated AX in wheat bread had similar positive effects as whole-grain rye bread on glucose and lipid metabolism.