Origin and practical significance of the sticky dough factor in 1BL/1RS wheats

When translocated into wheat, the short arm of the 1R chromosome of rye carries with it linked resistance genes to powdery mildew, stripe rust, leaf rust and stem rust. The translocation is also reported to increase yield potential of hard wheats. However, many doughs made from some 1BL/1RS hard wheats are unacceptable for breadmaking purposes because of excessive stickiness and mixing intolerance. 1BL/1RS wheats may be sticky because of: the inheritance of secalin proteins from rye and absence of key glutenin subunits; higher amounts and/or differences in the composition of cell wall polysaccharides, β‐glucans and pentosans; and/or the presence of a ferulic acid ester moiety residing with the water‐soluble fraction of 1BL/1RS flours. None of these hypotheses has been proven or disproven, to date, as a cause of excessive stickiness. Investigators have found that 1BL/1RS doughs are not uniformly sticky and are in some instances less sticky than non‐1BL/1RS doughs. Significant genotype–environment interactions have been reported for dough stickiness and flour quality characteristics of 1BL/1RS wheats. Investigators have generally failed to find significant differences in the breadmaking performance of 1BL/1RS and non‐1BL/1RS hard wheats despite a report that 1BL/1RS doughs break down and soften during high‐speed mixing. The 1BL/1RS translocation has been shown to reduce cookie spread of soft wheat flours but has no deleterious effects on cake volume or texture. © 2002 Society of Chemical Industry     

Effect of endo‐xylanase‐containing enzyme preparations and laccase on the solubility of rye bran arabinoxylan

Three commercial enzyme preparations with endo‐xylanase activity, namely Bio‐Feed Wheat, Bio‐Feed Plus and Grindamyl H 640, and laccase have been tested for their effects on the solubilisation of arabinoxylan (AX) in rye bran or autoclaved rye bran. Autoclaving efficiently increased the availability of AX for enzymatic degradation. Both Bio‐Feed Wheat (a monocomponent enzyme) and Bio‐Feed Plus (a multicomponent preparation with different enzymatic activities) efficiently degraded the autoclaved rye bran AX into lower‐molecular‐weight fragments. As much as 70% of the xylose residues and 58% of the arabinose residues in the autoclaved bran were soluble after treatment with Bio‐Feed Plus; the weight—average molecular weight of the detectable portion of these soluble polymers was 104 000 Da. Grindamyl H 640 solubilised only a small fraction of the AX in autoclaved rye bran; the molecular weight of these soluble fragments was higher than that of those released by the Bio‐Feed xylanases. Addition of laccase during treatment with Bio‐Feed Wheat or Grindamyl H 640 decreased the yield of water‐soluble AX. © 2003 Society of Chemical Industry     

The composition of a gel formed when wheat flour is suspended in phenol-acetic acid-water (1:1:1, w/v/v)

A gel which formed when wheat flour was suspended in phenol-acetic acid-water (1:1:1, w/v/v/) was fractionated into a protein-rich soluble fraction and a carbohydrate-rich insoluble fraction. Gel electrophoresis showed that the soluble fraction contained several proteins and had an amino acid composition with a high content of proline and glutamyl residues and a low content of lysine. The soluble fraction also contained lipids which were mainly phospholipids, phospholipid derivatives and glycolipids and other compounds, which yielded galactose and glucose after acid hydrolysis. The insoluble fraction contained a polysaccharide with similar properties to starch, and lipids which were mainly neutral fats, sterols and sterol esters. Both fractions contained arabinoxylans and mannans. The gel did not contain any nucleic acids. The protein-rich soluble fractions of gels prepared from other wheat flours and air-classified flour fractions, from wheat gluten and from rye and barley flours, showed marked differences in amino acid composition. It is concluded that a heterogeneous class of proteins, rather than specific proteins in fixed proportions, is involved in gel formation.     

Content,structure and viscosity of soluble arabinoxylans in rye grain from several countries

Rye grains from Finland, Canada, Sweden and Poland were extracted, during starch hydrolysis, with sodium acetate buffer at 95°C and soluble polymers were isolated by ethanol precipitation. The amount of sugar residues in the isolated polymers varied from 2.3 to 4.1% of rye dry matter with arabinose xylose and glucose residues predominant. High-field H-NMR analysis revealed that arabinoxylan I, containing terminal arabinose and un- and mono-substituted xylose residues, and arabinoxylan II, containing terminal arabinose and un- and double-substituted xylose residues, together with mixed-linked (1 ?3), (1 ?4)-β-D-glucans, were the dominating features in all samples of soluble polymers. On average, 46% of the xylose residues in arabinoxylan I and 57% in arabinoxylan II were substituted and the degree of substitution in the respective polymers was similar for all samples. The average content of arabinoxylan I ranged from 1.4% in samples from Canada to 1.7% in the Swedish samples and that of arabinoxylan II from 0.6% in samples from Poland to 1.0% in the Canadian samples. The viscosity of the soluble polymers was measured at a shear rate of 100 s^?1. It was shown by partial least-squares regression that in these samples the content of structural units characteristic of arabinoxylan II had a stronger correlation to viscosity than those of arabinoxylan I.     

An explanation for the combined effect of xylanase–glucose oxidase in dough systems

In the bakery industry, glucose oxidase is usually used in combination with xylanase. Although many theories exist on the mechanism of action of each enzyme, the positive effect of combining the two is as yet unexplained. In this paper we studied a possible basis for this synergy by focusing on the involvement of arabinoxylans. Water‐extractable arabinoxylans and water‐unextractable solids were studied in dough with or without glucose oxidase. Addition of glucose oxidase led to a stiffer and less extensible dough. Addition of arabinoxylans caused a further decrease in dough extensibility. Addition of xylanase could correct for this decrease. The role of arabinoxylans was further investigated by studying modified water‐extractable arabinoxylans and the effect of agents affecting arabinoxylan crosslinking (ferulic acid). Water‐extractable arabinoxylan was modified with xylanase to generate a low‐molecular‐weight fraction (WEAX_XYL). Alternatively, it was modified with NaOH to prepare a fraction with a decreased ferulic acid content (WEAX_OH). Addition of modified arabinoxylans diminished the effect of glucose oxidase. Glutenin macropolymer and water‐extractable arabinoxylan viscosity experiments were performed to obtain further detail on the role of arabinoxylans (AX). These results give rise to a new theory explaining the contribution of xylanase in its synergy with glucose oxidase. In this theory glucose oxidase not only catalyses the formation of protein disulfide bonds, but also of AX‐AX crosslinks. The latter negatively affect bread quality. Xylanase corrects for this latter effect by cleaving arabinoxylan complexes and generating small ferulic acid‐containing arabinoxylan fragments interfering with the crosslinking of high‐molecular weight arabinoxylans. Copyright © 2005 Society of Chemical Industry     

Secalin蛋白检测及其与面团黏性关系的研究

用SDS—PAGE检测了70个小麦品种是否带有黑麦Secalin蛋白，并测试了它们的面团黏性，用PCR检测了部分品种是否含有1RS染色体片断，结果表明：70％的品种为1B／1R易位系；有54．3％的品种面团发黏；带有黑麦Secalin蛋白的品种约有72．5％面团发黏，而不带有黑麦Secalin蛋白的品种只有30％面团发黏；影响面团黏性的主要因素为来源于黑麦的Secalin蛋白；PCR扩增结果表明，在我国存在不带有Sec-1基因的1B／1R小片断易位系。     

Influence of Pentosanase and Oxidases on Water-extractable Pentosans during a Straight Breadmaking Process

ABSTRACT: Effects of flour type and enzymes on total pentosans (TP) and water‐soluble pentosans (WSP) and composition of isolated water‐extractable pentosans (WEP) during a straight breadmaking process were investigated. Two wheat flours (F1, F2) and 3 enzymes (pentosanase, glucose‐oxidase (GOX) and lacasse (LAC)), and their combinations were used. The presence of pentosanase increased the WSP content while oxidases produced a decrease. Extractability of pentosans was greater for dough than for bread but the latter had higher purity. Major sugars were xylose (Xyl) and arabinose (Ara) with a xylose/arabinose ratio between 1.00 and 1.56. Molecular weight profiles (MWP) of WEP comprised 5 fractions with the same distribution for the 2 flours but different relative proportions.     

Effects of enzymes in fibre-enriched baking

The aim of the present study was to improve the quality of fibre-enriched wheat breads by enzymic treatment of the fibre fraction. The suitability of different enzymes in fibre-enriched baking and their effects on the dietary fibre content and the ratio of insoluble: soluble fibre content of the breads were studied. The enzyme preparations used were a hemicellulolytic culture filtrate of Trichoderma reesei, a specific (pI 9) xylanase of T reesei and Fermizyme, an α-amylase preparation containing a standardised level of hemicellulase activity. Rye bran was extracted in water (10% (w/w) suspension) to determine the solubilities of the β-glucans and pentosans. Addition of T reesei culture filtrate significantly increased the amount of extractable pentosan obtained from nonautoclaved rye bran. Rye bran supplementation (5%) of wheat flour increased the farinograph absorption and dough development time, but had little or no effect on stability and softening of the dough. The added enzymes decreased dough stability and increased softening. Addition of enzymes caused significant differences in the stickiness of the wheat doughs both with (P<0·003) and without (P<0·001) rye bran. Fermizyme significantly increased the stickiness of wheat doughs both with and without rye bran. The baking results of the fibre-enriched breads were improved by the added enzymes. Addition of T reesei culture filtrate increased the specific volume of the wheat breads both with and without rye bran by almost 20%. Enzyme mixtures were more efficient than individual xylanase in softening the bread crumb and reducing the staling rate of wheat breads both with and without rye bran. Incorporation of enzymes reduced the total dietary fibre content of the breads, but at least doubled the amount of soluble pentosan. The proportions of fluorescent cell walls in the breads were detected by microscopical image analysis. Enzyme addition caused the surface area of insoluble cell walls originating from wheat flours to decrease, suggesting that the enzymes exert more effects on wheat endorsperm cell walls than on bran particles. © 1998 SCI.     

Processing of rye bran influences both the fermentation of dietary fibre and the bioconversion of lignans by human faecal flora in vitro

Plant lignans are converted to mammalian forms, enterodiol and enterolactone, in the colon. Enhanced plasma or urinary enterolactone levels have been associated with lowered risk of cardiovascular diseases and breast cancer. Processed rye bran and its fractions were compared to ascertain the fermentation rates of fermentable carbohydrates and the bioconversion of lignans. Rye bran was extruded and treated with a food‐grade xylanase. Part of the xylanase‐treated rye bran was separated into a soluble rye bran extract and an insoluble residue, and a part of the xylanase‐treated rye bran was freeze‐dried without separation. All the samples were digested by pepsin and pancreatin and subsequently fermented with a human faecal inoculum in vitro. The consumption of carbohydrates, the productions of short‐chain fatty acids (SCFA), enterodiol and enterolactone were followed as a function of time. The soluble rye bran extract showed the fastest fermentation rate and the highest extent of fermentation determined as the consumption of neutral sugar residues (arabinose, xylose and glucose), the production of SCFA and the formation of enterodiol and enterolactone. Xylanase treatment enhanced the fermentation rate of extruded rye bran. An even a higher fermentation rate was observed for rye bran extract containing soluble carbohydrates. The amount of enterolactone precursors in rye seemed to be too low for enterolactone formation using an amount of substrate suitable for carbohydrate fermentation. However, xylanase treatment enhanced the availability of plant lignans from rye bran, as enterodiol formation was increased by the use of xylanase. Copyright © 2005 Society of Chemical Industry     

Treatments with Xylanase at High (90 %) and Low (40 %) Water Content Have Different Impacts on Physicochemical Properties of Wheat Bran

The aim of the work was to elucidate the impacts of treatment with xylanase at high (90 %) and low (40 %) water contents on the structural and physicochemical properties of wheat bran. The bran treatments at 40 % water content, both with and without added xylanase, resulted in a smaller average bran particle size, more changes in bran microstructure, and higher solubilization of polysaccharides than the corresponding treatments at 90 %. Also, the water holding capacity of bran (3.6?±?0.1 g water/g bran dm), determined by Baumann method, decreased more already after 4-h xylanase treatments at 40 % (2.4?±?0.1) than at 90 % (2.9?±?0.2). The solubility of salt-extractable bran proteins decreased during the treatments, especially at 40 %, also without added xylanase. Protein aggregation was detected in the SDS?+?DTT-extractable bran fraction, which also contained small proteins of 10–20 kDa not detectable in the untreated bran. The use of xylanase had only minor effect on bran proteins as compared to the treatments without added xylanase. The results indicate the large role of mechanical shear on the bran properties at 40 % water content. The low arabinose/xylose ratio (0.32) in the bran water extract after 24-h xylanase treatment at 40 %, however, suggests that the solubilization of arabinoxylan was caused by enzymatic action, and not by mechanical degradation. Arabinose/xylose ratio of the bran water extract decreased similarly during all the treatments, suggesting similar solubilization pattern of arabinoxylan at both water contents. The study showed that bran properties can be significantly modified by adjusting the water content and mechanical energy used in processing.     

Aleurone cells are the primary contributor to arabinoxylan oligosaccharide production from wheat bran after treatment with cell wall-degrading enzymes

Arabinoxylans and in particular arabinoxylan oligosaccharides (AXOS) from wheat are recognised for their prebiotic potential. A high-yield, non-chemical production of AXOS is therefore of interest when producing functional foods. This study investigated the enzymatic production of AXOS from wheat bran with the aim of establishing the main fraction contributing to production of AXOS. Fractions of wheat bran, outer pericarp and aleurone with two different purities were treated with the cell wall-degrading enzymes: xylanase, cellulase and β-glucanase. The yield of solubilised arabinoxylans upon treatment was greatest in the most pure aleurone fraction (164 g kg⁻¹) and lowest in the outer pericarp fraction (15 g kg⁻¹). The yield was mainly recovered as AXOS rather than soluble arabinoxylans and was negatively related to the arabinose/xylose ratio found in the raw material. In conclusion, wheat aleurone cell walls are the main contributor to the production of AXOS from wheat bran and this seems to depend on the A/X ratio of the raw material.     

In vitro fermentation of polysaccharides of rye,wheat and oat brans and inulin by human faecal bacteria

The in vitro fermentabilities of rye, wheat and oat brans and of a commercial fibre preparation, inulin, were compared. The brans were first digested enzymatically to remove starch and protein. The digested brans and inulin were then fermented with human faecal inoculum. The progress of fermentation was studied by following the consumption of carbohydrates and the production of short‐chain fatty acids and gases. Inulin, a short fructose polymer, was consumed significantly faster than the more complex carbohydrates of cereal brans. Carbohydrates of oat bran (rich in β‐glucan) were consumed at a higher rate than those of rye and wheat brans (rich in arabinoxylan). In all brans, glucose was consumed faster than the other main sugars, arabinose and xylose, and arabinose was degraded only slightly. The total production of short‐chain fatty acids was slightly higher with oat bran than with rye and wheat brans and inulin. In the fermentation of inulin, relatively more butyric acid and less propionic acid were produced than in the fermentation of brans. The decrease in pH was also greater in the case of inulin. Wheat bran led to a slightly slower gas formation than rye and oat brans. Formation of gases was fastest and greatest in the case of inulin. In conclusion, rye, wheat and oat brans were fermented in a rather similar way. Fermentation of the brans was different from that of inulin. Cereal brans might serve as a more balanced source of dietary fibre supplement than gas‐producing, readily fermentable polysaccharides such as inulin. © 2000 Society of Chemical Industry     

Effect of kilning on the composition of protein and arabinoxylan in wheat malt

To explore the effect of kilning on the quality of wheat malt, wheat variety LM21 was malted with three different kilning programmes. Protein composition and arabinoxylan, xylanase (EC 3.2.1.8) activity, diastatic power and free amino nitrogen (FAN) were evaluated. Arabinoxylan content and xylanase activity were monitored during the kilning process. The results showed that the malt obtained from the kilning programme A showed the highest diastatic power, Kolbach index, FAN and lowest wort viscosity. Total arabinoxylan content showed no significant change during the kilning process, while the water extractable arabinoxylan and the xylanase activity reached the maximum values at the kilning temperature of 55°C, after which the xylanase activity decreased with the increase in kilning temperature. Extending kilning time at 40–50°C increased the diastatic power, FAN and Kolbach index and reduced the wort viscosity. © 2019 The Institute of Brewing & Distilling     

Degradation of rye arabinoxylans in the large intestine of pigs

Four types of rye bread (based on whole rye, pericarp/testa, aleurone or endosperm) differing in arabinoxylan (AX) structure were fed to pigs. Collected intestinal material was extracted with cold water and 4 M potassium hydroxide, and the AX were characterised by methylation analyses. The endosperm AX were extensively and readily degraded in the caecum (0.78), whereas pericarp/testa AX were undegraded in the intestinal tract of pigs. Aleurone AX were also degraded to a large extent (faecal digestibility 0.73) but at a slower rate, and, in agreement, structural modification of aleurone AX also took place beyond the proximal colon. The differences in AX degradability correlated well with differences in water and alkali extractability and differences in structural characteristics of the AX. Endosperm AX were thus characterised by a large content of water‐extractable AX and pericarp/testa AX by a very high degree of (mono‐ and double‐) xylose substitution. In contrast, aleurone AX were characterised by the presence of an alkali‐extractable AX with a very low degree of substitution, which precipitated upon dialysis of the alkali extract. The faecal xylose substitution patterns were similar irrespective of diet. The study thus showed that the structural characteristics of a dietary fibre component influenced dietary fibre degradation in pigs, which may hold important implications for the colonic health in monogastrics. © 1999 Society of Chemical Industry     

Changes in crude arabinoxylan during cloudy wheat beer brewing on a production scale

As one of the major non‐starch polysaccharides in the cloudy wheat beer, arabinoxylan has a crucial influence on the wort viscosity, foam profile and stability of the beer. In this study, the cloudy wheat beer was fermented on a production scale with a ratio of barley to wheat malt of 1:1, during which the changes in arabinoxylan were monitored in order to determine the key steps which influence the content, substitution degree of arabinoxylan (A/X) and average degree of polymerization (avDP) value of crude arabinoxylan during cloudy wheat beer brewing. The results show that the total contents of crude arabinoxylan, arabinose, xylose and galactose increased until the end of mashing and then dropped with the addition of spent grain sparging water. The crude arabinoxylan decreased during the saccharification, and then stabilized at ~10.00 mg/g. During fermentation and storage, the content of crude arabinoxylan did not change remarkably. The A/X remained at ~0.50 in the process of wort preparation and brewing and the avDP value of crude arabinoxylan decreased during saccharification and then stayed at ~3.00 in the fermentation and storage phases, which was lower because the contents of free arabinose, xylose and galactose were not subtracted from the total contents of the sugars. Therefore, wort preparation is shown the key step influencing the changes in crude arabinoxylan during cloudy wheat beer brewing. Copyright © 2017 The Institute of Brewing & Distilling     

Effect of sourdough processing and baking on the content of enniatins and beauvericin in wheat and rye bread

The occurrence of the emerging mycotoxins enniatins (ENNs) and beauvericin (BEA) has been reported in Fusarium-infected cereals. To study the effect of sourdough processing and baking on ENN B, ENN B1, and BEA concentrations, a recently developed stable isotope dilution assay for these mycotoxins was used. After milling of wheat and rye grains naturally contaminated with ENN B and ENN B1, approximately 70–82 % of the two ENNs were found in the bran fraction and the rest remained in flour. BEA was added to flour before sourdough fermentation. In an experiment on a microscale, dough was fermented for 24 h at 30 or 40 °C, which reduced part of the ENNs and BEA in particular at 40 °C. On a standard scale, mixing, resting, and proofing of the bread dough resulted in 13–19 % reduction of the ENNs compared with flour, but in no significant change of BEA. The final baking at 200 °C for 25 min led to a further decrease of the ENNs and BEA, ranging from 9 to 28 % compared with fermented dough. In case of rye sourdough bread, greater reductions of ENNs were found in crust than in crumb. For both wheat and rye flours, overall 25–41 % of ENN B, ENN B1, and BEA were reduced during the whole sourdough bread-making process.     

Effect of 1B/1R Translocation in Wheat on Physical and Chemical Properties of Starch

Starches were isolated from near-isoline pairs of 1B/1R translocation wheats and their parents for determination of water binding capacity, swelling power, solubility, Amylograph viscosity, scanning electron microscopy, differential scanning calorimetry and bread baking characteristics. Translocation wheats had a statistically lower starch yield. The starches of these wheats had a lower swelling power at 60° and 80° and a reduction in Brabender viscosity after a 15 min holding period when compared with control starches. Texture scores of breads baked with starches from translocation wheats were better than those of control breads.     

Fractional extraction of cereal flour proteins

Wheat (Wichita), rye, barley, oat and maize flours were successively extracted with 0.04 m sodium chloride solution (3 × ), water (3 × ), 70% ethanol (3 ×) and 0.1 N acetic acid. The fractions and residues were analysed for nitrogen and subjected to starch-gel electrophoresis. Saline extractions chiefly removed the albumins and globulins of all five cereals. The prolamins of wheat, rye and barley appeared mostly in the three aqueous extracts but also, particularly, those of very low mobility, occurred in the alcoholic solutions. The acetic acid-soluble fractions of wheat, rye and barley were shown by electrophoresis under reducing conditions to be crosslinked by S.S bonds; those of rye and barley showed some characteristic differences from glutenin. Oats and maize were practically devoid of this fraction. Most of the protein of oats and maize was insoluble. Electrophoresis patterns after reduction were obtained from insoluble fractions, though there were differences among the genera. Both overall protein solubility and the quantity of the acetic acid-soluble fraction were correlated with baking quality. The presence of covalent crosslinks other than S.S in glutelin fractions is suspected.     

毛壳霉木聚糖酶B（CsXyn11B）的分泌表达及其在面包中的应用

目的:对毛壳霉（Chaetomium sp.）CQ31木聚糖酶B（CsXyn11B）进行分泌表达,以提高产酶水平并探究在面包烘焙中的应用价值。方法:将木聚糖酶基因在毕赤酵母中表达,高密度发酵提高其产酶水平,对酶学性质进行表征并将其应用在面包烘焙中。结果:重组菌经高密度发酵156 h,木聚糖酶酶活力为2788 U/mL。CsXyn11B最适pH为8.0,最适温度为65 ℃。CsXyn11B能够水解多种木聚糖底物,对燕麦木聚糖、小麦阿拉伯木聚糖、榉木木聚糖和桦木木聚糖的比酶活分别为1145.8、1041.7、692.3和653.3 U/mg。该酶水解阿拉伯木聚糖,水解产物以聚合度4~6的低聚木糖为主。在面包制作过程中加入3 mg/kg CsXyn11B使面包比容增加15.9%,面包硬度降低25.3%,4 ℃贮藏2 d后硬度比对照组降低17%。结论:毛壳霉木聚糖酶B的优良酶学特性使其在烘焙食品中具有良好的应用前景。     

Dietary fibre in bread and corresponding flours--formation of resistant starch during baking

Dietary fibre, assayed with an enzymatic/gravimetric method, was higher in wheat/rye bread than in the corresponding flours. The increase was most pronounced in crumbs from bread baked with mainly low-extraction-rate flour, and could be accounted for to a large extent as "resistant starch", i.e. a starch fraction available to amyloglucosidase only after solubilization with 2 m-KOH. The resistant starch was formed at dough-making and/or baking and did not increase further during freezing or storage at room temperature. The chemical modifications leading to resistant starch formation remain to be investigated. Starch-lipid complexes are probably not involved, since these are hydrolyzed by the heat-stable amylase used in the dietary fibre assay.