Composition and molecular structure of polysaccharides released from barley endosperm cell walls by sequential extraction with water, malt enzymes, and alkali

Arabinoxylans as Functional Food Ingredients: A Review

The health benefits of fibre consumption are sound, but a more compressive understanding of the individual effects of different fibres is still needed. Arabinoxylan is a complex fibre that provides a wide range of health benefits strongly regulated by its chemical structure. Arabinoxylans can be found in various grains, such as wheat, barley, or corn. This review addresses the influence of the source of origin and extraction process on arabinoxylan structure. The health benefits related to short-chain fatty acid production, microbiota regulation, antioxidant capacity, and blood glucose response control are discussed and correlated to the arabinoxylan’s structure. However, most studies do not investigate the effect of AX as a pure ingredient on food systems, but as fibres containing AXs (such as bran). Therefore, AX’s benefit for human health deserves further investigation. The relationship between arabinoxylan structure and its physicochemical influence on cereal products (pasta, cookies, cakes, bread, and beer) is also discussed. A strong correlation between arabinoxylan’s structural properties (degree of branching, solubility, and molecular mass) and its functionalities in food systems can be observed. There is a need for further studies that address the health implications behind the consumption of arabinoxylan-rich products. Indeed, the food matrix may influence the effects of arabinoxylans in the gastrointestinal tract and determine which specific arabinoxylans can be included in cereal and non-cereal-based food products without being detrimental for product quality.

Structural characteristics and rheological properties of alkali-extracted arabinoxylan from dehulled barley kernel

Arabinoxylan (BIF-60) was isolated from barley water-insoluble fiber (BIF) by ethanol precipitation at 60 % (v/v). BIF-60 was composed of xylose (48.5 %) and arabinose (30.3 %). Its average molecular weight was 1360 kDa. Methylation and 1D/2D NMR analysis showed that BIF-60 possessed β-(l→4)-xylan as backbone, comprised of un-substituted (1,4-linked β-Xylp, 56.9 %), mono-substituted (1,2,4-linked and 1,3,4-linked β-Xylp, 22.1 %) and di-substituted (1,2,3,4-lin4ked β-Xylp, 18.4 %) xylose units, as well as other residues (T-Araf-(1→, T-Xylp-(1→, →5)-Araf-(1→, →2)-Araf-(1→, →3)-Araf-(1→ and →4)-Glcp-(1→). BIF-60 exhibited shear-thinning behaviour, low gel stability and weak gelling ability at high concentrations. This work provides a theoretical and experimental basis for molecular structure and properties of the alkali-extracted arabinoxylan from barley kernel, which could guide further functional research and application of barley-derived arabinoxylan.

Structure-immunomodulatory activity relationships of Hedysarum polysaccharides extracted by a method involving a complex enzyme combined with ultrasonication

A new, more effective and environmentally friendly method involving a complex enzyme combined with ultrasonication was employed to extract and isolate three novel polysaccharides (HPS-MCs: HPS-MC, HPS-MC (50%) and HPS-MC (80%)) of Radix Hedysari. Compared with polysaccharides obtained using a traditional extraction method (hot water extraction, HPS-R), the yields and total carbohydrate contents of HPS-MCs were significantly higher. HPS-MC (80%) exhibited relatively strong immunomodulatory activity and a concentration-dependent dose-response relationship under cyclophosphamide (CP)-induced immunosuppressive conditions in mice models. To more comprehensively investigate the relationships between structural characteristics and immunomodulatory activity, HPS-MC (80%) was fractionated into three major homogeneous polysaccharide fractions (HPS-MC (80%)s: HPS-MC (80%)-1, HPS-MC (80%)-2, and HPS-MC (80%)-3). These three homogeneous polysaccharides had different mass percentages of monosaccharides species (rhamnose, arabinose, mannose, glucose, and galactose) by gas chromatography (GC) and different molecular weights and chain conformations by high-performance gel permeation chromatography coupled with multi-angle laser light scattering (HPGPC-MALLS), and promoted macrophage and splenocyte proliferation to different degrees. These findings indicated that HPS-MC (80%) had a prominent potential immune response, especially HPS-MC (80%)-2 and HPS-MC (80%)-3, and might be suitable candidates for functional foods or potential novel immunomodulators.

Tracking polysaccharides through the brewing process

Brewing is a highly complex stepwise process that starts with a mashing step during which starch is gelatinized and converted into oligo- and/or monosaccharides by enzymes and heat. The starch is mostly degraded and utilised during the fermentation process, but grains and hops both contain additional soluble and insoluble complex polysaccharides within their cell walls that persist and can have beneficial or detrimental effects on the brewing process. Previous studies have mostly been restricted to analysing the grain and/or malt prior to entering the brewing process, but here we track the fates of polysaccharides during the entire brewing process. To do this, we utilised a novel approach based on carbohydrate microarray technology. We demonstrate the successful application of this technology to brewing science and show how it can be utilised to obtain an unprecedented level of knowledge about the underlying molecular mechanisms at work.

The effect of pentosanase on the solubilisation and degradation of arabinoxylan extracted from whole and refined wheat flour

BACKGROUND

The quality improvement capability of pentosanase (Pn) for whole-wheat Chinese steamed bread (CSB) is not as efficient as that for refined CSB. However, the underlying mechanism remains to be elucidated. In this work, water-extractable arabinoxylan (WEAX) and water-unextractable solids (WUS) were extracted from whole and refined wheat flour, and then treated with Pn under the conditions similar to CSB-making. Solubilisation and degradation of arabinoxylan (AX) caused by Pn treatment were determined.

RESULTS

WEAX from whole flour exhibited higher molecular weight than that from refined flour before and after the treatment with equivalent Pn. Compared with WUS from refined flour, WUS from whole flour had a much lower dissolution degree but the degradation of AX released from the WUS was more efficiently. Moreover, AX released from WUS for refined flour showed a higher Ara/Xyl ratio and the percentage of residual ferulic acid in WUS decreased more significantly.

CONCLUSION

The difference in quality improvement degree for Pn in whole-wheat and refined CSB might be mainly explained by its effect on WUS. That is, Pn contributed much more to the solubilisation of WUS from refined flour but provoked degradation predominantly on AX solubilised from WUS isolated from whole flour. © 2016 Society of Chemical Industry.

Effects of dietary water-soaked barley on amino acid digestibility, growth performance, pork quality and Longissimus dorsi muscle fatty acid profiles in pigs

Two experiments were conducted to assess the feeding value of water-soaked barley (WB) as a replacement for dehulled barley (DB) in pigs. In experiment (Exp.) 1, eight barrows (body weight = 30.56 ± 0.78 kg) were fitted with a T-cannula and allotted to a duplicated 4 × 4 Latin square design: WB10, 100g/kg WB; WB20, 200 g/kg WB; DB10, 100 g/kg DB; and DB20, 200 g/kg DB. In Exp. 2, 80 barrows (body weight = 70.56 ± 1.29 kg) were used in a 56-day experiment: (i) WB15, 150 g/kg WB; (ii) WBD10, 100 g/kg WB and 50 g/kg DB; (iii) WBD5, 50 g/kg WB and 100 g/kg DB; and (iv) DB15, 150 g/kg DB. In Exp. 1, the apparent ileal digestibilities of total essential amino acids were higher (P < 0.05) in WB10 treatment than DB20. For Exp.2, the WB15 and WBD10 had higher pH and lower cooking loss (P < 0.05) than other two treatments. The WB15 treatment decreased (P < 0.05) the contents of palmitic acid (C16:0) in Longissimus dorsi muscle than WBD5 and DB15 treatments. In conclusion, it is suggested that water-soaked barley improved some amino acid digestibility and the cooking loss and moderate fatty acid profiles in Longissimus dorsi muscle.

Comparative proteomic analysis of Dan'er malts produced from distinct malting processes by two-dimensional fluorescence difference in gel electrophoresis (2D-DIGE)

The malting process is the controlled germination, followed by drying, of the barley grain. For brewing beer, the malting process is modified according to the features of the barley variety being malted. In China, there are two schedules routinely used for malting the widely grown Dan'er cultivar, processes I and II. The quality of malt produced with process II is considered to be superior to that from process I for Dan'er by maltsters and brewers. In the present study, comparative proteomic analysis was performed between Dan'er malts produced by malting processes I and II. The data showed that enzymes and proteins responsible for cell wall polysaccharide degradation and starch and protein hydrolysis were more abundant in malt produced by process II, leading to improved quality, especially for the commercially important filterability, saccharification time, and diastatic power (DP) quality traits. In addition, to verify the proteomic results, the activities of several key enzymes (α-amylase, β-amylase, and limit dextrinase) were compared between the two malts. This enabled the influence of malting process on malt quality to be determined and suggested malting process schedule changes to optimize the malting process for the Dan'er cultivar, especially for improving filterability, which is often deemed as suboptimal by maltsters and brewers.

Hardness methods for testing maize kernels

Maize is a highly important crop to many countries around the world, through the sale of the maize crop to domestic processors and subsequent production of maize products and also provides a staple food to subsistance farms in undeveloped countries. In many countries, there have been long-term research efforts to develop a suitable hardness method that could assist the maize industry in improving efficiency in processing as well as possibly providing a quality specification for maize growers, which could attract a premium. This paper focuses specifically on hardness and reviews a number of methodologies as well as important biochemical aspects of maize that contribute to maize hardness used internationally. Numerous foods are produced from maize, and hardness has been described as having an impact on food quality. However, the basis of hardness and measurement of hardness are very general and would apply to any use of maize from any country. From the published literature, it would appear that one of the simpler methods used to measure hardness is a grinding step followed by a sieving step, using multiple sieve sizes. This would allow the range in hardness within a sample as well as average particle size and/or coarse/fine ratio to be calculated. Any of these parameters could easily be used as reference values for the development of near-infrared (NIR) spectroscopy calibrations. The development of precise NIR calibrations will provide an excellent tool for breeders, handlers, and processors to deliver specific cultivars in the case of growers and bulk loads in the case of handlers, thereby ensuring the most efficient use of maize by domestic and international processors. This paper also considers previous research describing the biochemical aspects of maize that have been related to maize hardness. Both starch and protein affect hardness, with most research focusing on the storage proteins (zeins). Both the content and composition of the zein fractions affect hardness. Genotypes and growing environment influence the final protein and starch content and, to a lesser extent, composition. However, hardness is a highly heritable trait and, hence, when a desirable level of hardness is finally agreed upon, the breeders will quickly be able to produce material with the hardness levels required by the industry.