Total Arabinoxylan Research Articles

Changes in the content of fructans and arabinoxylans during baking processes of leavened and unleavened breads

Fructans and arabinoxylans (AXs) are prebiotics naturally occurring in cereal grains which have well-known beneficial effects on human health. However, the majority of grains consumed by humans are processed prior to the consumption. The effect of baking on fructan and AX levels has been studied in rye breads, but there is a scarcity of data on the presence of fructans and AXs in wheat breads. Therefore, the aim of this study was to investigate the effect of baking on stability of fructans and total AXs in breads made from both wheat and rye flours. Bread loaves were baked using an automatic bread maker Breville BBM100 (Sydney, Australia). Sugar analysis was performed using high-performance liquid chromatography on a Dionex ICS-3000 unit. This study showed slight loss of total AXs (6–10 %) during preparation processes of leavened, yeast-free and unleavened breads. In contrast, there was 40–60 % degradation in fructan content of leavened, but no significant losses of fructans in unleavened breads. Yeast-free breads had higher contents of both fructans and AXs than leavened breads. Generally, smaller changes in the content of these prebiotics were apparent in wholemeal and rye than in white breads. It seems that differences in the structures of AXs and fructans in cereals, and the presence of yeast play significant role in determining stabilities of these components during baking.

Effects of high hydrostatic pressure treatment on the enhancement of functional components of germinated rough rice (Oryza sativa L.)

This study was performed to evaluate the enhancement of functional components of germinated rough rice. Rough rice was germinated at 37°C for 6days, and subjected to a high hydrostatic pressure treatment (HPT) at 30MPa for 24h (HP24) and 48h (HP48). Germinated rough rice without HPT (HP0), HP24, and HP48 were analysed for their functional components. The highest γ-aminobutyric acid, total arabinoxylan, and tricin 4′-O-(threo-β-guaiacylglyceryl) ether contents were 121.21mg/100g, 10.6%, and 85.82μg/g, respectively, after HP48 for 2days. γ-Oryzanol contents increased from 23.19–36.20mg/100g (at HP0) to 31.80–40.32mg/100g (at HP48). The highest vitamin B (60.99mg/100g) and E (4.07mg/100g) contents were observed after HP24 for 5 and 2days, respectively. These results suggest that a combination of HPT and germination efficiently enhances the functional characteristics of rough rice.

Content and molecular weight of water-extractable arabinoxylans in wheat malt and wheat malt-based wort with different Kolbach indices

Arabinoxylans (AXs) are partially water-extractable polymers that cause problems of viscosity and filterability during beer brewing. This study investigated the effects of Kolbach index (KI) on water-extractable AXs (WEAXs). KI had positive correlations with extract (r = 0.845) and free amino nitrogen (FAN) (r = 0.958). The contents of malt WEAXs (WEAXsm), total AXs and wort AXs (WAXs) were 10.8-11.6 g kg⁻¹, 57.5-60.8 g kg⁻¹ and 137.5-140.5 mg per 100 mL respectively and the corresponding arabinose/xylose (A/X) ratios were 0.52-0.56, 0.55-0.62 and 0.48-0.50. The molecular weight (Mw) ranged from 4.92 × 10⁴ to 6.93 × 10⁴ Da for WEAXsm and from 1.24 × 10⁴ to 2.90 × 10⁴ Da for WAXs. KI had negative correlations with the average degree of polymerization (avDP) of malt (r = -0.877) and wort (r = -0.978). Wort viscosity showed a positive correlation with the Mw of WEAXsm (Mwm) (r = 0.821). Increasing KI can promote the degradation of the xylan backbone, while it cannot affect the branching of the polymer chain and the content and Mw of WEAXs.

Valuation of brewer's spent grain using a fully recyclable integrated process for extraction of proteins and arabinoxylans

The objective of this work was to design an integrated process to valuate brewer's spent grain (BSG) proteins and arabinoxylans (AX) to be used as food ingredients. For this purpose, a sequential extraction of proteins and AX from BSG with increasing alkali (KOH or NaOH) concentrations of 0.1M, 0.5M, and 4M, was optimized. A ratio of 1:2 (w/v) (weight of BSG by volume of alkali solution) at room temperature for 24h was preferred to minimize reagents and energy consumption. To fully integrate the process, alkaline extracts were acidified to pH3 with citric acid, to obtain the protein-rich fractions. The AX were recovered by ethanol precipitation and citric acid and ethanol were recycled. This integrated extraction process allowed a yield of 82–85% of the BSG total proteins and 66–73% of total AX with formation of a cellulose rich residue almost devoid of nitrogen.

Genotypic and Environmental Variations of Arabinoxylan Content and Endoxylanase Activity in Barley Grains

Arabinoxylan (AX) content in barley grains is an important quality determinant when barley is used as raw material of malt or beer production. The cultivar and environmental variations of total arabinoxylan (TAX), water extractable arabinoxylan (WEAX) and endoxylanase activity (EA) were investigated using eight barley cultivars growing at seven locations with diverse environmental conditions. The results showed that both barley cultivar and location significantly affected the TAX, WEAX and EA levels, but the variations of TAX content and EA were mainly attributed to cultivar, while the impact of location on WEAX content was greater than that of cultivar. Correlation analysis indicated that TAX was significantly correlated to WUAX.

Wheat Arabinoxylan Structure Provides Insight into Function

ABSTRACTRecent attention to dietary fiber in wheat (Triticum aestivum L.) has invigorated research in the nonstarch carbohydrate arabinoxylan (AX). AX molecules are composed of a linear xylose backbone with arabinose substitutions along the backbone. These arabinose substituents can also carry a ferulic acid moiety. AX molecules can be fractionated into two categories based on extraction properties that have a structural and conformational basis: water‐extractable (WEAX) and water‐unextractable (WUAX) molecules. The ferulic acid moieties also allow for oxidative cross‐linking between AX molecules or the tyrosine residues of proteins. The contents of total AX and WEAX molecules are primarily influenced by genetic differences; however, there is also evidence of environmental influence on content. There are several useful methods for quantifying AX molecules, providing varying levels of structural information as well as accuracy and precision. The high water‐absorption capacity of AX molecules results in a strong influence of AX on end‐use quality. Whereas WEAX molecules, in particular, tend to be detrimental for the quality of soft wheat products such as cookies, WEAX molecules are beneficial to the quality of hard wheat products such as bread. The role of WUAX molecules among the range of soft wheat products is as yet unclear; however, WUAX molecules tend to have a detrimental influence on bread. Because of the variable influence of AX structure on end‐use product functionality, closer examination of structure–function relationships may provide key insights into how to direct breeding efforts to maximize these relationships between AX molecules and other ingredients. Further investigation is necessary to obtain a more complete understanding of how the arabinose substitution levels and patterns affect end‐use quality and how the genetic basis of these traits can be resolved and manipulated for optimum end‐use quality.

Molecular Features of Wheat Endosperm Arabinoxylan Inclusion in Functional Bread.

Arabinoxylan (AX) is a major dietary fibre component found in a variety of cereals. Numerous health benefits of arabinoxylans have been reported to be associated with their solubility and molecular features. The current study reports the development of a functional bread using a combination of AX-enriched material (AEM) and optimal commercial endoxylanase. The total AX content of bread was increased to 8.2 g per 100 g available carbohydrates. The extractability of AX in breads with and without endoxylanase was determined. The results demonstrate that water-extractable AX (WE-AX) increased progressively through the bread making process. The application of endoxylanase also increased WE-AX content. The presence of 360 ppm of endoxylanase had positive effects on the bread characteristics in terms of bread volume and firmness by converting the water unextractable (WU)-AX to WE-AX. In addition, the molecular weight (Mw) distribution of the WE-AX of bread with and without endoxylanase was characterized by size-exclusion chromatography. The results show that as the portion of WE-AX increased, the amount of high Mw WE-AX (higher than 100 kDa) decreased, whereas the amount of low Mw WE-AX (lower than 100 kDa) increased from 33.2% to 44.2% through the baking process. The low Mw WE-AX further increased to 75.5% with the application of the optimal endoxylanase (360 ppm).

Spectroscopic analysis of diversity in the spatial distribution of arabinoxylan structures in endosperm cell walls of cereal species in the HEALTHGRAIN diversity collection

Two varieties each of spelt (Triticum aestivum var. spelta), durum wheat (Triticum turgidum var. durum), rye (Secale cereale), barley (Hordeum vulgare), oats (Avena sativa), einkorn (Triticum monococcum var. monococcum) and emmer (Triticum turgidum var. dicoccum) (all members of the Pooideae sub-family of grasses) were selected according to variation in their contents of soluble and/or total arabinoxylan (AX) determined during the HEALTHGRAIN diversity screen, together with one genotype of the related “model” grass species Brachypodium distachyon. The spatial distribution of low substituted (LS-AX) and highly substituted arabinoxylan (HS-AX) was determined using FT-IR spectroscopic mapping of transverse thin cross-sections consisting of cell walls only. Variation in cell wall AX composition was observed between the cereals, and compared with that observed for wheat (Triticum aestivum var. aestivum). One line of each cereal type was analysed in more detail using 1H NMR spectroscopy. The results of the two analyses were consistent, showing variation in the composition and structure of the endosperm cell wall AX that is consistent with the genetic relationships of the cereals studied.

A Critical Assessment of the Quantification of Wheat Grain Arabinoxylans Using a Phloroglucinol Colorimetric Assay

Arabinoxylans (AX) of wheat (Triticum aestivum L.) play a critical role in processing, end‐use quality, and human health and nutrition. Consequently, an efficient, accurate method of AX quantification is desirable. The objective of this work was to evaluate a standard phloroglucinol colorimetric method for quantification of wheat AX. The method is based on the formation and spectrophotometric quantification of a phloroglucide product that results from the reaction of furfural produced during the condensation of pentose sugars with phloroglucinol. Method parameters, including reaction reagents and reaction times, were varied to identify areas for improved accuracy and consistency. Phloroglucide formation at three xylose concentrations was examined over time. The optimal reaction reagents and reaction times were determined based upon improved consistency in xylose quantification. The optimized method was used on xylose and arabinose standards and on whole meal wheat samples for total and water‐extractable AX content. Glucose was shown to be unnecessary in the reaction and was eliminated. A second‐order polynomial equation provided a slightly better fit to the nearly linear standard xylose curve. A reduced concentration of phloroglucinol of 10% was found to give equivalent results to the standard 20%. Optimum reaction time was 25 min, and it required the inclusion of all reagents. The phloroglucide product decreased in absorbance over time such that, within the range of xylose concentration examined, about 40–50% of the colored product was lost over 100 min; however, the rate of loss was linear over time. Four operators performed the optimized method on whole wheat meal samples for total and water‐extractable AX. Inter‐ and intraoperator variation was identified as an area requiring further study and improvement. However, all operators tended to rank the samples in a consistent manner. Compared with a gas chromatography–flame ionization detection method, the phloroglucinol method underestimated total AX by about 2.3% and water‐extractable AX by about 0.08%.

Distribution of Total, Water‐Unextractable, and Water‐Extractable Arabinoxylans in Wheat Flour Mill Streams

ABSTRCTArabinoxylans are a minor but important constituent in wheat that affects bread quality, foam stability, batter viscosity, and sugar snap cookie diameter. Therefore, it is important to determine the distribution of arabinoxylans in flour mill streams to better formulate flour blends. Thirty‐one genetically pure grain lots representing six wheat classifications common to the western U.S. were milled on a Miag Multomat pilot mill, and 10 flour mill streams were collected from each. A two‐way ANOVA indicated that mill streams were a greater source of variation compared to grain lots for total arabinoxylans (TAX), water‐unextractable arabinoxylans (WUAX), and water‐extractable arabinoxylans (WEAX). TAX and WUAX were highly correlated with ash at r = 0.94 and r = 0.94, respectively; while the correlation for WEAX and ash decreased in magnitude at r = 0.60. However, the 5th middlings mill streams exhibited disparity between TAX and ash content as well as between WUAX and ash content. This may indicate that TAX and WUAX in mill streams are not always the result of bran contamination. Cumulative extraction curves for TAX, WUAX and WEAX revealed increasing gradients of arabinoxylans parallel to extraction rate. Therefore, arabinoxylans may be an indicator of flour refinement.

Refrigerated Dough Quality: Effect of Environment and Genotypes of Hard Red Spring Wheat

Refrigerated dough products use wheat flour as their primary ingredient, so the quality and chemical composition of the flour determine the quality of the final product. Six varieties of hard red spring wheat, grown in 3 locations in Minnesota, U.S.A., were evaluated for use in refrigerated dough products. Total arabinoxylan percentages in the flours ranged from 0.97 to 1.54. Xylanase activity of the flour was measured and ranged from 0.20 to 0.84 mU/g. An important factor in the suitability for refrigerated dough is the syruping during storage. A large amount of variability in dough syruping was observed among the varieties and locations when the extent of dough syruping was measured over a period of 10 d. The mean dough syruping on day 10 ranged from 2.05% to 14.83%. Despite the significant interaction effect of genotype and environment, 2 varieties, Glenn and Oklee, had lower dough syrup formation with greater stability across growing locations and storage days than other varieties. Practical Application: Refrigerated dough production is one of the fastest growing segments of the ready-to-use food industry. Well-formulated and processed refrigerated doughs are practical to consume and should stay fresh during extended periods of storage; thus, maintenance of dough quality during refrigeration is critical. This study was designed to perform the research on genotypic and environmental effects on variations in dough syruping during refrigeration storage of doughs from hard red spring wheats.

Wheat Bran AX Properties and Choice of Xylanase Affect Enzymic Production of Wheat Bran‐Derived Arabinoxylan‐Oligosaccharides

ABSTRACTWheat bran‐derived arabinoxylan‐oligosaccharides (AXOS) recently have been shown to potentially exert prebiotic effects. In this study, 15 bran samples obtained by milling different wheat cultivars were treated with xylanases from Hypocrea jecorina (XHJ), Aspergillus aculeatus (XAA), and Pseudoalteromonas haloplanktis (XPH) to assess the effect of bran source and xylanase properties on the AXOS yield and structure. The total arabinoxylan (AX) extraction yield was higher with XHJ (8.2–10.7%) and XAA (8.2–10.8%) than with XPH (6.9–9.5%). Irrespective of the enzyme, a significant negative correlation was observed between extraction yield and arabinose to xylose (A/X) ratio of bran AX (r = –0.7), but not between yield and bran AX level. The A/X ratio of the extracted material was 0.27–0.34 for all bran samples and all enzymes, which combined with yield data and microscopic analysis, indicated primary hydrolysis of aleurone and nucellar epidermis AX. The average degree of polymerization (avDP) of the extracted AX was very low for all enzymes (2–3), owing to the release of high levels of monomeric arabinose and xylose. The release of these monosaccharides could be ascribed to 1) the activity of wheat bran‐associated enzymes (arabinofuranosidases and xylosidases); 2) the hydrolytic properties of the xylanases themselves; and 3) the presence of xylosidases as contaminations in enzyme preparation, in that order of importance. Heat treatment of bran before xylanase treatment significantly decreased the levels of monomeric arabinose and xylose in the extract, without affecting the extraction yield, resulting in a higher avDP of 3–7, thus yielding true AXOS. Overall, for AXOS production, wheat cultivars with a low bran A/X ratio of the AX are preferable as starting materials, and inactivation of bran‐associated enzymes before incubation is desirable. The XHJ xylanase was the best enzyme for wheat bran‐derived AXOS production.

Environment and Genotype Effects on the Content of Dietary Fiber and Its Components in Wheat in the HEALTHGRAIN Diversity Screen

Within the HEALTHGRAIN diversity screen, the variability of the contents of dietary fiber (DF) and components thereof was studied in wheat. Furthermore, the contribution of genotype and environment to this variability was estimated. The levels of total DF (TDF), total nonstarch polysaccharide (TOTNSP), water-extractable nonstarch polysaccharide (WENSP), total arabinoxylan (TOTAX), lignin, and beta-glucan in whole meal, flour, and/or bran varied approximately 1.8-fold. The highest variability was observed for the water-extractable arabinoxylan (WEAX) level in flour and bran (approximately 3.7-fold). Genotype and environment contributed to a similar extent to the variability in TDF, TOTNSP, and TOTAX content in wheat. The observed relatively high impact of genotype-environment interaction suggests that the levels of these constituents are weak breeding parameters. The WENSP level is a more stable parameter as the effect of the interaction term was much less than the impact of genotype. For TOTAX and WEAX in flour, WEAX in bran, beta-glucan in whole meal, and extract viscosity, wheat genotype determined approximately 50% or higher of the variation observed, whereas the impact of the genotype-environment interaction was relatively low. These findings suggest that the health-related and technological functionality of wheat can be directed to a certain extent by selection of appropriate wheat varieties.

Genotype and Environment Variation for Arabinoxylans in Hard Winter and Spring Wheats of the U.S. Pacific Northwest

ABSTRACTThe development of high‐quality wheat (Triticum aestivum L.) cultivars depends on a thorough understanding of the constituents of grain and their variation due to genetics and environment. Arabinoxylans (pentosans) are key constituents of wheat grain and have broad and far‐reaching influences on milling and baking quality. However, variation in arabinoxylans due to genotype and environment are not fully understood. In this study, 25 hard winter and 25 hard spring wheat commercial cultivars and advanced breeding lines developed from eight public and private breeding programs in the U.S. Pacific Northwest were analyzed for water‐extractable and total arabinoxylan contents (WE‐AX and total AX), and the proportion of total AX that was water‐extractable. Winter and spring genotypes were grown in three environments each. The results indicated that there were significant differences among both sets of hard wheat genotypes for WE‐AX, total AX, and proportion of total AX that was WE‐AX. The WE‐AX and total AX mean content ranges for the winter cultivars were 0.390–0.808 and 3.09–4.04%, respectively; and for the spring cultivars 0.476–0.919 and 3.94–4.70%, respectively. WE‐AX as a percentage of total AX was similar between the two genotype sets, 11.7–23.0%. Arabinoxylan fractions were generally not correlated with grain protein, test weight, and kernel hardness. The two highest correlations for winter wheats were between protein and total AX (r = –0.40) and test weight and percentage of total AX that were water‐extractable (r = 0.37) for winter wheats. Among spring wheats, single‐kernel characterization system hardness was negatively correlated with WE‐AX and proportion of total AX that was WE‐AX (r = –0.46 and –0.51, respectively). Although often significant, arabinoxylan fractions were usually not highly intercorrelated, indicating some independence of traits. Notable genotypes, being especially high or low for one or more arabinoxylan fraction and, thus, candidates for further genetic study and cross‐breeding, included Juniper, Eddy, and ORN980995 winter wheats, and Hollis, Alta Blanca, and WQL9HDALP spring wheats. Although the results indicate that arabinoxylan fractions of wheat grain can be highly influenced by environment, there is clear support for the existence of genetic differences, especially for WE‐AX and the proportion of total AX that is water‐extractable. As such, the manipulation of arabinoxylan content of wheat grain seems to be a reasonable breeding objective.

보리의 제맥과정 중 Arabinoxylan의 용해성 변화

Barleys at different malting stages from steeping to 5 day germination were investigated for soluble, insoluble, and total arabinoxylans at three different extraction temperatures of 21, 45 and 65℃. Slight differences in total arabinoxylan levels in barleys were observed during malting stages. During germination, initially insoluble arabinoxylan could be more soluble, thus the solubilized arabinoxylan tended to increase until 4 day germination. The proportion of soluble arabinoxylan in germinating barleys was increased from ambient temp (21℃) to 45 or 65℃. Two barley malt samples were selected at two different stages of germination, well-modified malt germinated for 96 hr and poorly-modified malt for 60 hr, and mashed isothermally at 45, 55, 65, or 75℃ for 2 hr. Increasing temperature over 45 to 75℃ slightly decreased the amount of arabinoxylan solubilized in wort. Arabinoxylan content of wort from well-modified malt was not significantly different from poorly-modified malt at all mashing temperatures.

Ball Milling Improves Extractability and Affects Molecular Properties of Psyllium (Plantago ovata Forsk) Seed Husk Arabinoxylan

Psyllium (Plantago ovata Forsk) seed husk (PSH) is very rich in arabinoxylan (AX). However, its high gelling capacity and the complex nature of the AX make it difficult to process. In this study, ball milling was investigated as a tool for enhancing PSH AX water extractability and molecular mass (MM). A 48 h laboratory-scale ball mill treatment under standardized optimal conditions reduced the PSH average particle size from 161 microm for the untreated sample to 6 microm. Concurrently, it increased the water-extractable AX (WE-AX) level from 13 (untreated PSH) to 90% of the total PSH AX. While the WE-AX of the untreated PSH had a peak MM of 216 kDa and an arabinose to xylose (A/X) ratio of 0.20, WE-AX fragments from ball mill-pretreated PSH had a peak MM of 22 kDa and an A/X ratio of 0.31. Ball milling further drastically reduced the intrinsic viscosity of PSH extracts and their water-holding capacity. Prolonged treatment brought almost all AX (98%) in solution and yielded WE-AX fragments with an even higher A/X ratio (0.42) and a lower peak MM (11 kDa). While impact and jet milling of PSH equally led to significant reductions in particle size, these technologies only marginally affected the water extractability of PSH AX. This implies that ball milling affects PSH particles and their constituent molecules differently than impact and jet milling.

Effects of genotype, harvest year and genotype-by-harvest year interactions on arabinoxylan, endoxylanase activity and endoxylanase inhibitor levels in wheat kernels

The effects of genotype, harvest year and their interaction on the levels of arabinoxylans (AX), endoxylanases and endoxylanase inhibitors in wheat were studied using 14 varieties grown in three successive growing periods with diverse climatological conditions. Relations with more commonly evaluated wheat characteristics such as yield, thousand kernel weight, specific weight, protein level, Hagberg falling number (HFN) and α-amylase activity level were examined. Water extractable arabinoxylan (WE-AX) levels in wheat varied much more than total arabinoxylan (TOT-AX) levels. This variability was mainly genetically determined, but harvest year also had an important effect. Total endoxylanase activity levels varied more than a factor of 20 between the different wheat samples. Endogenous endoxylanases typically accounted for only 10–15% of this activity, while wheat-associated microbial endoxylanases accounted for the remaining 85–90%. However, when preharvest sprouting occurred, the contribution of endogenous endoxylanases could sometimes amount to over 40% of this total activity. Endogenous endoxylanase activity levels were mainly determined by the interaction of genotype and harvest year, while wheat-associated microbial endoxylanase activity levels were predominantly determined by genotype alone. Endogenous and microbial endoxylanase activity levels were strongly correlated, suggesting that wheat varieties which are susceptible to preharvest sprouting are often also susceptible to microbial contamination. The TAXI and XIP-type endoxylanase inhibitor levels varied by a factor of 8 and 1.8, respectively. They were mainly determined by genotype and were rather similar in the different growing periods.

Influence of Cultivar and Environment on Water‐Soluble and Water‐Insoluble Arabinoxylans in Soft Wheat

ABSTRACTArabinoxylans are hydrophilic nonstarch polysaccharides found in wheat grain as minor constituents. Arabinoxylans can associate with large amounts of water through hydrogen bonding and can form oxidative gels. These properties are important factors in end‐use quality of wheat. The objective of this study was to delineate the influence of wheat cultivar and growing environment on variation in water‐soluble (WS‐AX), waterinsoluble (WI‐AX), and total (TO‐AX) arabinoxylan contents of flour and whole grain meal. This study included seven spring and 20 winter soft white wheat cultivars grown in 10 and 12 environments, respectively (each evenly split over two crop years). Univariate analysis of variance (ANOVA) and multivariate analysis of variance with canonical analysis (MANOVA) was used to evaluate sources of variation. Variation in arabinoxylan contents and absolute amounts (xylose equivalents) among the two cultivar sample sets (spring and winter) was similar, and both cultivar and environment were significant sources of variation. The cultivar‐by‐environment interaction was relatively unimportant. Results indicate that the variation in arabinoxylan content is primarily influenced by cultivar and secondarily influenced by environment. Within arabinoxylan fractions, WS‐AX content is primarily influenced by genotype, while WI‐AX content is more greatly influenced by the environment.

Studies on water-extractable arabinoxylans during malting and brewing

The most important non-starch polysaccharides in barley grain are β-glucan and arabinoxylans. Arabinoxylans are partially water-extractable, high-molecular-weight polymers that contribute to viscosity and membrane filterability. Changes to arabinoxylans content and endo-xylanase activity during germination and kilning were studied. This paper was aimed at determining the composition of total arabinoxylans and water-extractable arabinoxylans in malt and observing their changes during brewing. The water-extractable and total arabinoxylans contents of six barley malts and wheat malt varied in the range of 0.42–0.98% and 3.84–6.90%, respectively. Their l-arabinose-to- d-xylose ratio ranged between 0.49–0.59 (total arabinoxylans) and 0.60–0.85 (water-extractable arabinoxylans). Contents of arabinoxylans in worts mainly originated from the soluble part of arabinoxylans in malt. The use of rice adjunct decreased arabinoxylans contents of wort and beer. The correlation between arabinoxylans and viscosity was investigated. Results showed that water-extractable arabinoxylans in wort have positive and higher correlation value with wort viscosity than those of β-glucan in wort, and both water-extractable arabinoxylans and β-glucan in beer have significant correlation ( p < 0.01) with beer viscosity.

The combined use of hull-less barley flour and xylanase as a strategy for wheat/hull-less barley flour breads with increased arabinoxylan and (1→3,1→4)-β-D-glucan levels

Bread-making with a composite flour (CF) consisting of 60% wheat flour (WF) and 40% hull-less barley flour, increased the total and soluble (1→3,1→4)-β-D-glucan and total arabinoxylan (AX) contents of dough and bread samples, but decreased the specific bread loaf volume. A xylanase insensitive to inhibition by Triticum aestivum L. xylanase inhibitor (TAXI) and xylanase inhibiting protein (XIP), increased loaf volume by 8.8 and 20.1% for WF and CF breads, respectively. Xylanase addition not only markedly improved loaf volume of CF bread, but also increased the soluble AX content of the WF and CF dough and bread samples because of conversion of water-unextractable AX into soluble AX. The xylanase had no impact on the extractability and molecular weight of (1→3,1→4)-β-D-glucan, but (1→3,1→4)-β-D-glucan was degraded during bread-making probably because of endogenous β-glucanase activity. Taken together, the results clearly show that the combined use of hull-less barley flour and a xylanase active during bread making, lead to palatable breads with high total and soluble AX and (1→3,1→4)-β-D-glucan contents. The sum of total AX and (1→3,1→4)-β-D-glucan was 1.70% for WF bread and 3.06% for CF bread, while the sum of soluble AX and (1→3,1→4)-β-D-glucan was 0.49 and 1.41% for control WF and CF xylanase supplemented breads, respectively.