Glutenin Macropolymer Content Research Articles

The impact of extrusion parameters on the glutenin macropolymer content of flour-water dough

Wheat quality, dough properties and the extent of dough formation can be predicted by the glutenin macropolymer (GMP) content. To provide the selection and control of GMP content in the flour-water dough by using extrusion technology, the relationship between the GMP content and the extrusion parameters was investigated. Different dough moistures (25%–45%), barrel temperatures (30 °C–50 °C), screw speeds (100–200 rpm), pressures (with die or without die), and extrusion rounds (1–3 rounds) were investigated during the flour-water dough extrusion processing trials, and the GMP content was detected. The results demonstrated that the sodium dodecyl sulfate (SDS)-soluble protein content increased from 83.0 mg/g to 100.7 mg/g and the GMP content decreased from 30.8 mg/g to 18.3 mg/g when the specific mechanical energy (SME) increased from 30.09 kJ/kg to 178.14 kJ/kg, which indicated the GMP was converted to SDS soluble proteins. Dough moisture and extrusion round significantly facilitate the reduction of GMP content. Temperature has a relatively insignificant effect on GMP content. The GMP content suggests the negative relationship (r = −0.77) with SME. This study highlighted the complex interplay of extrusion processing variables that affect the interaction of protein components, with consequent effects on protein solubility.

Effect of oil contents on gluten network during the extrusion processing

To investigate a comparative evaluation of the gluten polymerization properties at different oil contents during the extrusion processing, the electrophoretic profiles of the gluten, free sulfhydryl (SH) compounds, the secondary structure of gluten, glutenin macropolymer contents and gluten network were measured. Five gluten samples were formulated by adding different oil contents. The low molecular weight contents of gluten decreased as well as the high molecular weight contents increased during the extrusion processing. The free SH of gluten at 8 or 10% oil content drops significantly to a minimum. The β-sheets contents of gluten have significantly difference between the treatments and control, except for 15 and 20% oil content treatments. Confocal laser scanning microscopy of mixed glutens correlated to the degree of oil contents with the gluten in the bi-continuous gluten network.

A wheat-Aegilops umbellulata addition line improves wheat agronomic traits and processing quality.

Wheat processing quality is mainly correlated with high-molecular-weight glutenin subunits (HMW-GS) of grain endosperm. In bread wheat, the number of HMW-GS alleles are limited. However, wheat relative species possess numerous HMW-GS genes. In our previous study, a pair of novel HMW-GS 1Ux3.5+1Uy1.9 was characterized in Aegilops umbellulata. In this work, a novel wheat-Ae. umbellulata addition line, GN05, carrying a pair of 1U chromosome was developed and identified via cytogenetic analysis. Protein composition analysis indicated that GN05 carried HMW-GS of Ae. umbellulata. Accumulation of glutenin macropolymer (GMP) showed that GN05 had a much higher GMP content than the recurrent parent Chinese Spring. Rheological characteristics were analyzed by mixing test and the dough quality of GN05 was significantly improved compared to Chinese Spring. The results presented here may provide a valuable resource for the improvement of bread wheat quality.

Deletion of high-molecular-weight glutenin subunits in wheat significantly reduced dough strength and bread-baking quality

BackgroundHigh-molecular-weight glutenin subunits (HMW-GS) play important roles in the elasticity of dough made from wheat. The HMW-GS null line is useful for studying the contribution of HMW-GS to the end-use quality of wheat.MethodsIn a previous work, we cloned the Glu-1Ebx gene from Thinopyrum bessarabicum and introduced it into the wheat cultivar, Bobwhite. In addition to lines expressing the Glu-1Ebx gene, we also obtained a transgenic line (LH-11) with all the HMW-GS genes silenced. The HMW-GS deletion was stably inherited as a dominant and conformed to Mendel’s laws. Expression levels of HMW-GS were determined by RT-PCR and epigenetic changes in methylation patterns and small RNAs were analyzed. Glutenins and gliadins were separated and quantitated by reversed-phase ultra-performance liquid chromatography. Measurement of glutenin macropolymer, and analysis of agronomic traits and end-use quality were also performed.ResultsDNA methylation and the presence of small double-stranded RNA may be the causes of post-transcriptional gene silencing in LH-11. The accumulation rate and final content of glutenin macropolymer (GMP) in LH-11 were significantly lower than in wild-type (WT) Bobwhite. The total protein content was not significantly affected as the total gliadin content increased in LH-11 compared to WT. Deletion of HMW-GS also changed the content of different gliadin fractions. The ratio of ω-gliadin increased, whereas α/β- and γ-gliadins declined in LH-11. The wet gluten content, sedimentation value, development time and stability time of LH-11 were remarkably lower than that of Bobwhite. Bread cannot be made using the flour of LH-11.ConclusionsPost-transcriptional gene silencing through epigenetic changes and RNA inhibition appear to be the causes for the gene expression deficiency in the transgenic line LH-11. The silencing of HMW-GW in LH-11 significantly reduced the dough properties, GMP content, wet gluten content, sedimentation value, development time and stability time of flour made from this wheat cultivar. The HMW-GS null line may provide a potential material for biscuit-making because of its low dough strength.

Aggregation characteristics of protein during wheat flour maturation.

The protein aggregation characteristics of three types of freshly milled wheat flour with high, medium or low gluten were investigated during 90 days of maturation. Changes in the content and particle size of the glutenin macropolymer (GMP), contents of sulfhydryl groups and disulfide bonds (SS), and secondary structure and molecular weight distribution of the protein were determined. For high, medium and low gluten flour, GMP content increased to 22.25, 13.72 and 10.32 g kg-1 ; free sulfhydryl group content decreased by 5.5%, 4.1% and 4.4%; and SS content increased by 1.6%, 1.8% and 2%, respectively. The proportion of β-sheet and random coil increased, and the proportion of α-helix and β-turns decreased. The polymeric protein content increased, whereas that of gliadin decreased. Protein aggregation mediated by SS cross-linking helped develop a stronger gluten network. The findings provide theoretical support for the changes in protein structure during flour maturation and also help to predict the quality of wheat flour and its products. © 2018 Society of Chemical Industry.

Effects of pentosanase and glucose oxidase on the composition, rheology and microstructure of whole wheat dough

In the present study, the effects of pentosanase (Pn) and glucose oxidase (GOX) on the properties of whole wheat steamed buns dough were investigated, including the composition, rheology, and microstructure, to reveal the effects and mechanisms of action of these two enzymes in whole wheat steamed buns making. Compared with the Control, the dough exhibited a higher content of water extractable arabinoxylan and a stronger solubility in protein in the presence of Pn. Additionally, Pn-treated dough showed high extensibility, with the gluten matrix more open and the starch granules more visible. On the other hand, the addition of GOX decreased the number of free sulfhydryls and increased the content of glutenin macropolymer (GMP), indicating the formation of disulfide bonds. Reducing SDS-PAGE of albumin and globulin suggested the generation of large protein aggregates and the conjugation of protein-polysaccharide by non-disulfide covalent bonds. The GOX-treated dough was significantly strengthened, which generated a more continuous and highly dense gluten network. Although the effects of Pn and GOX on the dough were considerably different, they both significantly changed the rheology and microstructure of the dough, due to the solubilization of water un-extractable arabinoxylan and the increase of GMP and the formation of protein-polysaccharide conjugates. These effects observed for steamed buns could be extended to other fermented flour products.

Effects of water deficit on breadmaking quality and storage protein compositions in bread wheat (Triticum aestivum L.).

Water deficiency affects grain proteome dynamics and storage protein compositions, resulting in changes in gluten viscoelasticity. In this study, the effects of field water deficit on wheat breadmaking quality and grain storage proteins were investigated. Water deficiency produced a shorter grain-filling period, a decrease in grain number, grain weight and grain yield, a reduced starch granule size and increased protein content and glutenin macropolymer contents, resulting in superior dough properties and breadmaking quality. Reverse phase ultra-performance liquid chromatography analysis showed that the total gliadin and glutenin content and the accumulation of individual components were significantly increased by water deficiency. Two-dimensional gel electrophoresis detected 144 individual storage protein spots with significant accumulation changes in developing grains under water deficit. Comparative proteomic analysis revealed that water deficiency resulted in significant upregulation of 12 gliadins, 12 high-molecular-weight glutenin subunits and 46 low-molecular-weight glutenin subunits. Quantitative real-time polymerase chain reaction analysis revealed that the expression of storage protein biosynthesis-related transcription factors Dof and Spa was upregulated by water deficiency. The present results illustrated that water deficiency leads to increased accumulation of storage protein components and upregulated expression of Dof and Spa, resulting in an improvement in glutenin strength and breadmaking quality. © 2018 Society of Chemical Industry.

Effects of thermal and mechanical treatments on the physicochemical properties of wheat flour

Planetary ball milling is a possible way to improve the technological properties of wheat flour by thermal and mechanical modifications. In the present study, roller milled common wheat flours (Triticum aestivum L.) were additionally modified in a ball mill by varying mill parameters such as rotation speed and grinding time. As a result of ball milling, the flours experienced temperatures of up to 100 °C, the range of particle sizes strongly increased as well as the content of damaged starch. The treated flours were also analyzed for the protein distribution by SDS-polyacrylamide-gel electrophoresis and proteins were quantitated by an extraction/high-performance liquid chromatography (Osborne fractionation) and an extraction/gel permeation chromatography procedure (SDSL/GMP fractionation). Intense mechanical/thermal treatment led to a decrease of the content of extractable protein and shifted ethanol-soluble gliadins to the glutenin fraction. Cysteine-containing alpha- and gamma-gliadins initially soluble in 60% ethanol were bound to ethanol-insoluble glutenins by thiol–disulfide interchange reactions. Linked to that, a high level of modification also significantly decreased the gliadin/glutenin ratio and increased the glutenin macropolymer content. Cysteine-free omega5- and omega1,2-gliadin types were only weakly affected by milling. Heating induced by mechanical treatment is supposed to be mainly responsible for these effects. Thiol–disulfide interchange can also explain the increase of the particle size after intense ball milling, because flour particles could stick together via disulfide bonds between proteins located on the surface of different particles.

Functionality of ovalbumin during Chinese steamed bread-making processing

Hen egg is commonly used in some cereal-based food, including cakes and bread. Ovalbumin, one of the major components of egg white protein, can affect the performance of the food product. The interaction between ovalbumin and gluten protein and its effect on property of dough and quality of Chinese steamed bread was investigated in this study. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) patterns indicated that ovalbumin was surprisingly not incorporated in glutenins by covalent bond, whereas size-exclusion high-performance liquid chromatography showed that glutenin macropolymer content in glutenins increased slightly. Furthermore, dynamic rheology experiments indicated ovalbumin led to a decrease inG′ andG″ of dough. Based on molecular dynamic simulation and SDS-PAGE results, it was inferred that ovalbumin was not hydrolyzed by endopeptidases during dough fermentation and crosslinked to gluten proteins during steaming. Finally, ovalbumin improved maximum dough height (Hm) during dough development and specific volume of Chinese steamed bread.

Development of a wheat-Aegilops searsii substitution line with positively affecting Chinese steamed bread quality.

A wheat-Aegilops searsii substitution line GL1402, in which chromosome 1B was substituted with 1Ss from Ae. searsii, was developed and detected using SDS-PAGE and GISH. The SDS-PAGE analysis showed that the HMW-GS encoded by the Glu-B1 loci of Chinese Spring was replaced by the HMW-GS encoded by the Glu-1Ss loci of Ae. searsii. Glutenin macropolymer (GMP) investigation showed that GL1402 had a much higher GMP content than Chinese Spring did. A dough quality comparison of GL1402 and Chinese Spring indicated that GL1402 showed a significantly higher protein content and middle peak time (MPT), and a smaller right peak slope (RPS). Quality tests of Chinese steamed bread (CSB) showed that the GL1402 also produced good steamed bread quality. These results suggested that the substitution line is a valuable breeding material for improving the wheat processing quality.

Glutenin macropolymer particles size distribution of six wheat varieties in eastern China

Size distribution of glutenin macropolymer (GMP) particles significantly affects the quality of final products in wheat. Six wheat varieties in eastern China were used for investigating the GMP content, particle size distribution and their relation. The results showed that the particle diameter of GMP changed from 0.38 μm to 269 μm. A typical bimodal curve of volume distribution of particles with peak values ranged from 4.44 μm to 5.36 μm and from 45.76 μm to 116.30 μm, respectively. Number distribution of particles showed the typical population with peak values in the range of 0.57-1.00 μm. Proportions of granules 80 μm were in the range of 17.1%-47.8%, 32.1%-50.3% and 10.2%-38.1% of total volume, respectively. The content of GMP was negatively correlated with the volume of GMP particles 80 μm. The results suggested that the greater percentage of larger GMP particles is, the more GMP content there is in wheat grain.

Study of the mechanism of improvement due to waxy wheat flour addition on the quality of frozen dough bread

Waxy wheat flour (WWF) was substituted for 10% regular wheat flour (RWF) in frozen doughs and the physicochemical properties of starch and protein isolated from the frozen doughs stored for different time intervals (0, 1, 2, 4 and 8 weeks) were determined to establish the underlying reasons leading to the effects observed in WWF addition on frozen dough quality. Using Nuclear Magnetic Resonance (NMR), Differential Scanning Calorimeter (DSC) and X-ray Diffraction (XRD) among others, the gluten content, water molecular state, glutenin macropolymer content, damaged starch content, starch swelling power, gelatinization properties, starch crystallinity and bread specific volume were measured. Compared to RWF dough at the same frozen storage condition, 10% WWF addition decreased dry gluten and glutenin macropolymer contents and T23 proton density of frozen dough, but increased the wet gluten content, T21 and T22 proton density. 10% WWF addition also decreased damaged starch content, but increased starch swelling power, gelatinization temperature and enthalpy, crystallinity of starch and bread specific volume of frozen dough. Results in the present study showed that the improvement observed due to WWF addition in frozen dough bread quality might be attributed to its inhibition of redistribution of water molecules bound to proteins, increase in damaged starch content and decrease in starch swelling power.

Effects of glu-1 and glu-3 allelic variations on wheat glutenin macropolymer (GMP) content as revealed by size-exclusion high performance liquid chromatography (SE-HPLC)

Gluten macropolymers (GMPs), formed by seed storage proteins glutenins and gliadins through intermolecular disulfide bond, confer dough viscoelasticity andwheat processing quality. Glutenins consist of highand low molecular weight glutenin subunits (HMW-GS, LMW-GS)encoded by Glu-1 and Glu-3 loci, respectively. The allelic variations at both loci have important effects on GMP content and breadmaking quality. In this study, GMP extraction and size-exclusion high performance liquid chromatography (SE-HPLC) separation were optimized, and then applied to investigate the effects of Glu-1 and Glu-3 allelic variations on GMP content using different wheat genotypes, chromosome substitution lines and near-isogenic lines (NILs). The results showed that the optimized GMP extraction and SE-HPLC protocol could obtain a reproducible separation and reliable quantitation of GMP content with small samples. The allelic variations at Glu-1 and Glu-3 were closely related to GMP content. Particularly, Glu-D1 dencoded 1Dx5+1Dy10 subunits, Glu-A3a and Glu-B3 hencoded an abundant LMW-B subunit respectively had positive effects on GMP content and bread making quality. The introgress of HMW-GS and LMW-GS into bread wheat from related genomes could significantly increase GMP content, indicating that wheat related species has potential gene resources for breadmaking quality improvement. Our results demonstrated that SE-HPLC could serve as an effective tool for rapid separation and quantitation of GMPs and had potential application for gluten quality screening in the early generations during wheat quality improvement program.

The Combination of Rhizopus chinensis Lipase and Transglutaminase Affects the Rheology and Glutenin Macropolymer Properties of Frozen Dough

The combination of Rhizopus chinensis lipase (RCL) and transglutaminase (TG) was previously reported to improve the quality of frozen dough bread. In this study, the effects of RCL, TG, and their combination on the modification of glutenin macropolymer (GMP) and rheological properties of dough during frozen storage were investigated. Frozen storage changed both GMP and rheology properties of dough. TG treatment significantly decreased the ratio of high‐molecular‐weight glutenin subunits to low‐molecular‐weight glutenin subunits and GMP content in fresh dough, and GMP particle size increased. The effect of RCL on GMP properties was not significant, but its combination with TG dramatically increased the proportion of the larger particles and weighted average volume (D4.3) in GMP. The treatment with the enzyme combination could have inhibited the depolymerization of GMP, which slowed down the decrease rate of some parameters such as GMP content, proportion of larger particles, D4.3, and release of free amino and thiol groups during frozen storage. The modification of GMP properties by enzyme treatment weakened the effect of the freezing process on rheological properties of dough, especially TG treatment and its combination with RCL. Correlation between GMP particle size and dough properties (dough tensile force and elastic modulus) after freezing and enzyme treatment were confirmed.

Influence of Vacuum Mixing on Structural Characteristics and Physical Properties of Noodle Dough

The effects of vacuum mixing on the structural characteristics and physical properties of noodle dough were investigated using three leading Chinese wheat cultivars. Texture profile analysis showed that vacuum mixed doughs when sheeted all gave significantly higher levels of adhesiveness, elasticity, and chewiness than doughs from nonvacuum mixing. The cross section of sheeted dough mixed at 0.06 MPa had a more continuous and compact microstructure with fewer holes and gaps, as well as more even protein distribution at the surface, as evidenced by scanning electron microscopy and Fourier transform infrared microimaging. However, a higher degree of vacuum was detrimental to the developed network for weak dough. Dough mixed at 0.06 MPa had higher glutenin macropolymer content and lower free thiol group concentration compared with nonvacuum mixed doughs, which may largely relate to the improvement of dough texture. The development of the gluten network for weak gluten flour was more sensitive to the degree of vacuum.

Effect of different water supply on accumulation of high molecular weight glutenin subunits and glutenin macropolymers in near-isogenic wheat lines

Accumulations of high molecular weight glutenin subunits (HMW-GS) and glutenin macropolymer (GMP) in wheat grains are important indicators of grain quality. Two near-isogenic wheat lines, Line 11 (HMW-GS null, 7 + 9, 5 + 10) and Line 12 (HMW-GS null, 17 + 18, 5 + 10), were used to evaluate the impacts of different water supply on HMW-GS and GMP accumulation, and the GMP particle distributions in the grains. Three irrigation levels were implemented in a field and a pot experiment, respectively. Results indicated that drought is beneficial for grain desiccation in the two wheat lines at late filling stage. Compared to mild and excess watering, the total HMW-GS concentration at maturity was much lower when subjected to soil water deficit. Both drought and excess watering led to a reduced glutenin particle size and GMP content at maturity, indicating that a mild water supply could promote the accumulation of GMP and formation of lager glutenin particles. As opposed to Line 12, Line 11 showed an increase in accumulation of GMP and larger glutenin polymers.

Effects of sulphur fertilizer on glutenin macropolymer content and particle size distribution in wheat grain

Effects of sulphur fertilizer on glutenin macropolymer content and particle size distribution in wheat grain

Impact of water extractable arabinoxylan from rye bran on the frozen steamed bread dough quality

Impact of water extractable arabinoxylan from rye bran on frozen steamed bread dough quality was investigated in terms of the bread characteristics, ice crystallization, yeast activity as well as the gluten molecular weight distribution and glutenin macropolymer content in the present study. Results showed that water extractable arabinoxylan significantly improved bread characteristics during the 60-day frozen storage. Less water was crystallized in the water extractable arabinoxylan dough during storage, which could explain the alleviated yeast activity loss. For all the frozen dough samples, more soluble high molecular weight (Mw≈91,000–688,000) and low molecular weight (Mw≈91,000–16,000) proteins were derived from glutenin macropolymer depolymerization. Nevertheless, water extractable arabinoxylan dough developed higher glutenin macropolymer content with lowered level of soluble low molecular weight proteins throughout the storage. This study suggested water extractable arabinoxylan from rye bran had great potential to be served as an effective frozen steamed bread dough improver.

Quality properties and expression profiling of protein disulfide isomerase genes during grain development of three spring wheat near isogenic lines

Three wheat glutenin near isogenic lines (NILs) CB037A, CB037B and CB037C were used to investigate their quality properties and the transcriptional expression profiles of PDI gene family during grain development. Our purpose is to understand the relationships between the dynamic expression of different PDI genes and glutenin allelic compositions related to gluten quality. The results showed that glutenin allelic variations had no significant effects on main agronomic traits and yield performance, but resulted in clear gluten quality changes. CB037B with 5+10 subunits had higher glutenin macropolymer (GMP) content and better breadmaking quality than CB037A with 2+12 while the lack of Glu-B3h encoding one abundant B-subunit in CB037C significantly reduced GMP content, dough strength and breadmaking quality. The dynamic expression patterns of eight protein disulfide isomerase (PDI) genes during grain development detected by quantitative real-time polymerase chain reaction (qRT-PCR) showed the close correlations between higher expression levels of PDI3-1, PDI5-1 and PDI8-1 and the presence of 5+10 subunits. Meanwhile, Glu-B3h silence resulted in significant decrease of expression levels of five PDI genes (PDI3-1, PDI5-1, PDI6-1, PDI7-2 and PDI8-1), suggesting the vital roles of certain PDI genes in glutenin and GMP synthesis and gluten quality formation.

Correlations between gluten aggregation properties defined by the GlutoPeak test and content of quality-related protein fractions of winter wheat flour

The gluten aggregation properties of 19 winter wheat cultivars were investigated using a rapid small-scale (7 min, 8.5 g flour) technique (GlutoPeak test, GPT). Correlations between GPT indices and gliadin (GLIA), glutenin (GLUT), SDS-soluble protein (SDSS), and glutenin macropolymer (GMP) concentrations were established. Two groups of samples were distinguished based on the shape of their GPT curves. Flours of group 1 gave curves with a slower buildup in torque (measured as aggregation time) and a higher area under the curve at peak (maximum torque), compared to those of group 2. Group 1 was characterized by lower GLIA and higher GLUT and GMP contents than group 2. GLIA (r = 0.70, p ≤ 0.001) and SDSS (r = 0.59, p ≤ 0.01) concentrations were significantly correlated to peak torque. GLUT and GMP contents were correlated to the aggregation time (GLUT: r = 0.72, p ≤ 0.001; GMP: r = 0.77, p ≤ 0.001) and the area under the curve at peak (GLU: r = 0.68, p ≤ 0.01; GMP: r = 0.78, p ≤ 0.001), confirming the importance of GMP for gluten strength. GPT could be an alternative to the labor-intensive quantitation of quality related protein fractions of wheat flour.