Glutenin Macropolymer Particle Research Articles

Dynamic Changes in Glutenin Macropolymer during Different Dough Mixing and Resting Processes.

The glutenin macropolymer (GMP), which is an important component of the glutenin protein in wheat flour, plays a prominent role in governing dough properties and breadmaking quality. This study investigated the changes in GMP properties during the mixing and resting stages of dough processing. The results show that the GMP content decreases by about 20.20% when the mixing time increases from 3 to 5 min, while increasing the resting time can lead to restoration of some GMP contents. Resting promotes greater formation of large-sized GMP particles, which is likely related to the increased disulfide bond content in the GMP during this process. In contrast, the mechanical force of mixing causes GMP depolymerization and formation of smaller particles. Furthermore, after mixing, the protein secondary structure tends to be disordered, the protein morphology becomes irregular, and the protein subunit ratio changes. Thus, mixing has many of the opposite effects to resting, although resting can (to some extent) restore the properties of the GMP after mixing. However, excessive resting time can lead to negative results, reflected in lower disulfide bond (SS) and GMP contents, and more irregular particle sizes. The presented results suggest that dough mixing induces rearrangement of the dough’s protein structure, and resting somewhat restores the chemical bonds and internal protein structure.

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.

Effect of extra cysteine residue of new mutant 1Ax1 subunit on the functional properties of common wheat

Subunit pair 1Dx5 + 1Dy10 was recognized as superior subunit combination in wheat and contained an extra repetitive-domain cysteine residue in 1Dx5 that was important for understanding the formation of dough viscoelasticity. In this research, one specific serine codon of the 1Ax1 gene corresponding to the extra cysteine residue of 1Dx5 was substituted by a cysteine codon through site-directed mutagenesis. Four homozygous transgenic lines (T4) expressing the mutant 1Ax1 gene (mut1Ax1) were produced. Their greater dough strength and stability were confirmed by mixograph and were associated with highly increased gluten index, larger amounts of gluten macropolymers, larger size distribution for glutenin macropolymer particles and varied sodium-dodecyl-sulfate sedimentation volumes, compared with those of the one line expressing wild 1Ax1 that had similar expression level of transgene. The contents of β-sheets in dough and disulfide groups in gluten of the mut1Ax1 transgenic lines were significantly increased. The microstructure of dough mixed to peak showed a more continuous gluten matrix in the mutant transgenic lines than the one line mentioned-above. It was concluded that the extra cysteine residue of mutant 1Ax1 subunit plays a positive role in contributing to dough strength and stability of wheat by cross-linking into gluten aggregates through inter-chain disulfide bonds.

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.

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.

Phosphorus affects high-molecular-weight glutenin subunits and glutenin macropolymer size distribution in wheat grains

SUMMARYTwo winter wheat (Triticum aestivumL.) cultivars, Jimai20 and Shannong12, differing in phosphorus (P) utilization efficiency, were selected to study the effect of P application rate on changes in glutenin macropolymer (GMP) size distribution and the content of high-molecular-weight glutenin subunits (HMW-GS) in wheat grain. Four P levels (0, 40, 100 and 160 kg/ha) were applied under N1 (112·5 kg/ha) and N2 (225 kg/ha) conditions in the field, in 2008/09 and 2009/10. The results showed that increased P levels favoured HMW-GS synthesis under N1 conditions, but had a less pronounced effect under N2. When compared with the control, the volume proportions of <10 μm GMP particles in grains of both cultivars were significantly decreased, and those of >100 μm were increased in response to P application. The volume proportions of 10–100 μm GMP particles in the cultivars Jimai20 and Shannong12 were respectively lower and higher in response to P application than with no P fertilizer. At maturity, for both cultivars, total HMW-GS content was negatively correlated with GMP particle volume of <10 μm, but positively correlated with that of >100 μm. These observations suggest that both P and N affect protein synthesis in wheat grains and there exists a relationship between HMW-GS content and the synthesis of large GMP particles (>100 μm). The N×P interaction was the most important factor to regulate the HMW-GS and GMP contents.

Variation of high-molecular-weight glutenin subunits and glutenin macropolymer particle distribution in wheat grains produced under different water regimes

The components and contents of high-molecular-weight glutenin subunits (HMW-GS) in wheat grains affect glutenin macropolymer (GMP) size, which is considered an important flour quality trait in wheat. Four wheat cultivars (Shiluan 02-1, Yannong 24, Jinan 17 and Lumai 21) with different end-use qualities were used to investigate the HMW-GS and GMP contents, and the GMP particle distributions in grain produced under irrigated and rainfed conditions. The percent volume of GMP particles and the contents of HMW-GS and GMP were affected by genotype and soil water. Genotype×soil water interaction was significant only for GMP particles <12μm and >100μm in the growing season of 2010–2011. Irrigated and rainfed conditions had different influences on the GMP particle distribution in the four cultivars. Compared to irrigated treatment, the rainfed treatment had higher accumulations of HMW-GS and GMP, especially in cultivars Yannong 24, Jinan 17 and Lumai 21. Rainfed conditions also increased the proportion of large size particles of GMP, indicating that different water regimes had an effect on grain quality. According to correlation coefficients (r), the contents of HMW-GS and GMP in grains were negatively correlated with the volume of <12μm GMP particles, but positively correlated with GMP particles >100μm.

Responses of Glutenin Macropolymer Particle Distribution to Heat Stress in Wheat Grain

Glutenin macropolymer (GMP), a major glutenin fraction, is affected by both genotypic and environmental factors. However, few studies have focused on the effects of heat stress on the characteristics of GMP in wheat (Triticum aestivum L.) grains. The high‐yielding winter wheat cultivar, Zhengmai 366, was grown in pots at the Scientific and Educational Station of Henan Agricultural University during the 2010–2011 and 2011–2012 growing seasons to investigate the response of GMP particle to high temperature (HT). The experiment was performed with a completely randomized design using three replicates. Plants were grown in the natural environment and then transferred to a climate‐controlled greenhouse for two periods of HT treatments (38°C): (i) from 7 days after anthesis (DAA) to 10 DAA, and (ii) from 17 to 20 DAA, before being transferred back to the natural environment. Glutenin macropolymer particle size distribution was analyzed by laser diffraction. Results showed that heat stress led to a significant reduction in the proportion of GMP particles &lt;10 μm, and a concomitant increase in particles &gt;60 μm, yet had little effect on the number distribution of GMP particles. The proportion of GMP particles &gt;60 μm was positively correlated with GMP and protein concentrations, but negatively correlated with protein yield. Heat stress significantly reduced the protein and starch yields despite the fact that the proportion of GMP particles &gt;60 μm and the concentrations of GMP and protein all increased.\

Polymerization of Glutenin during Grain Development and Quality Expression in Winter Wheat in Response to Irrigation Levels

ABSTRACTChanges in the content and size distribution of glutenin were monitored using size‐exclusion‐high performance liquid chromatography (SE‐HPLC) during grain filling under field conditions in two seasons. Effects of irrigation levels on the constituent polypeptides (high molecular weight and low molecular weight glutenin unit), polymerization index (the percentage of sodium dodecyl sulfate [SDS]‐insoluble glutenins in total glutenins) of glutenin, glutenin macropolymer (GMP) particle size, dough mixing properties, and baking quality were examined. Drought or excess watering led to a reduced polymerization index at maturity resulting from modification of grain desiccation and accumulation of SDS‐insoluble glutenin. Glutenin particle size at maturity decreased under drought or excess watering and was associated with reduced ratio of a high molecular weight glutenin subunit to a low molecular weight glutenin subunit (HMW‐GS:LMW‐GS). The polymerization index of glutenin and GMP particle size were significantly positively correlated to dough stability times and loaf volume whereas no significant correlation existed among flour protein content, wet gluten content, dough stability times, and loaf volume. Therefore, dough mixing properties and baking quality were affected by irrigation levels mainly through changing the polymerization index of glutenin and GMP particle size in flour.

Changes of Glutenin Subunits due to Water–Nitrogen Interaction Influence Size and Distribution of Glutenin Macropolymer Particles and Flour Quality

ABSTRACTThe composition of high‐molecular‐weight glutenin subunit (HMW‐GS) and low‐molecular‐weight glutenin subunit (LMW‐GS) in wheat (Triticum aestivum L.) kernel affects the size of glutenin macropolymer (GMP), which is considered the important flour quality traits in wheat. Three wheat cultivars with different end‐use quality were used to study the effects of water–nitrogen (W × N) management on relative HMW‐GS and GMP contents. Under irrigation, increased N levels promoted the accumulation of HMW‐ and LMW‐GS, GMP content, and the proportion of the larger particle of GMP, with higher yield and better end‐use quality. Under rainfed conditions, increased N fertilizer also increased protein content in the three cultivars. As opposed to ‘Gaocheng8901’, ‘Shannong1391’ and ‘Taishan23’ got higher HMW‐ and LMW‐GS contents and larger GMP particles, but reduced yields of both. Irrigation increased the yield markedly, the N application significantly affected the glutenin, but the W × N interaction was not significant. On one hand, increased N levels improved the dough development time by increasing the numbers of larger GMP particles and enhancing volume and surface area percentages on the other. It was suggested that the interaction was a complicated network and some individual effect might be important. When managing for wheat yield and quality, growers should first consider the water factor, then the N fertilizer factor to improve the end‐use quality of wheat.

Effects of Phosphorus Fertilizer on Accumulation of High Molecular Weight Glutenin Subunits and Glutenin Macropolymer Size Distribution in Wheat Grain

For gaining insights into the relationship between the accumulation of high-molecular-weight glutenin subunit(HMW-GS) and the distribution of glutenin macropolymer(GMP) in wheat(Triticum aestivum L.),Shannong 12,a cultivar with high glutenin,was used in a field experiment with four phosphorus(P) application levels(0,40,100,and 160 kg ha-) under low nitrogen(112.5 kg ha-1) and normal nitrogen(225 kg ha-1) conditions,respectively.The result showed that HMW-GS in grains formed before 14 d after anthesis,and its content at maturity was higher in P application treatments than in the treatment with no P fertilizer applied.Phosphorus was in favor of the accumulation of HMW-GS under the low nitrogen(N) condition,but caused a negative effect in high P levels under the normal N condition.The content of GMP particle in 10 μm in diameter was significantly reduced with increasing P application.The effect increased with increasing P level under the low N condition,but showed the largest reduction at P level of 100 kg ha-1 and the smallest reduction at P level of 40 kg ha-1.For GMP particle in 10–100 μm and 100 μm groups,their contents tended to increase with more P applied under both N conditions.Under the normal N condition,there was no significant effect of P level on the number distribution of GMP particle.At maturity,the content of HMW-GS was negatively correlated with the volume of GMP particle in 10 μm group,but positively correlated with that in 10–100 μm group.The result suggested that larger GMP particles have higher HMW-GS content than the smaller GMP particles.

HMW-GS Accumulation and GMP Size Distribution in Grains of Shannong 12 Grown in Different Soil Conditions

To study the accumulation of high-molecular-weight glutenin subunit (HMW-GS) and its relation to glutenin macropolymer (GMP) particle distribution, wheat ( Triticum aestivum L.) cultivar Shannong 12 was grown in a pool experiment under 3 soil textures. The sampled spikes were partitioned into superior and inferior grains. The HMW-GS were separated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Fourteen days after anthesis, HMW-GS formed in both superior and inferior grains and its content was higher in superior grain than in inferior grain, showing stronger ability for accumulating HMW-GS in the superior grain. HMW-GS accumulation and GMP content were the highest in clay soil, followed by sandy and loam soils. The diameter of GMP particle ranged from 0.37 to 245 μm. The distributions of GMP volume and surface area showed the pattern of two-peak curve, and the GMP number distributed in the pattern of single-peak curve. For GMP particles that larger than 100 μm in superior grain, the percentages of number and volume were significantly higher than those in inferior grain. Correlation analysis showed that the contents of HMW-GS and GMP were negatively correlated with the volume percentage of GMP particles less than 10 μm and less than 100 μm, and positively correlated with GMP particles larger than 100 μm. The result suggested that larger GMP particles have higher HMW-GS content in wheat grain.

Effect of Transglutaminase on Properties of Glutenin Macropolymer and Dough Rheology

ABSTRACTThe effect of transglutaminase (TG) on glutenin macropolymer (GMP) properties could help to understand changes in bread quality. The aim of the present study was to analyze modifications in GMP and dough properties caused by TG addition. Transglutaminase introduced cross‐links to gluten proteins, mainly high molecular weight glutenins. This effect modified the protein structure and markedly increased dough strength. These changes in the structure of glutenins increased SDS solubility and decreased GMP content and GMP storage modulus. However, TG increased GMP particle size, notably at higher doses. TG affected rheological characteristics of dough in that increasing TG doses decreased tan δ, and increased G'. In all the studies conducted, the TG increased GMP polymer size, but contrary to what was expected, this increase did not involve an increase in GMP content. These results confirmed the effect of TG on dough quality and the great differences found with different TG doses.

Effect of simple shear on the physical properties of glutenin macro polymer (GMP)

Gluten plays a key role in determining the end-use quality of wheat flour. The important role of the highly aggregated fraction of gluten, glutenin macropolymer (GMP), in dough properties opens up new possibilities for revealing underlying mechanisms related to dough processing. Using a new shear cell and advanced methodology to study the GMP, we investigated the effect of simple shear on the physical properties of this fraction. Shear processing was compared with z-blade mixing, which involves both shear and elongational forces. Measurement of the amount of GMP and glutenin particle size distribution revealed large differences between simple shearing and z-blade mixing processes. In contrast to z-blade mixing, simple shearing at comparable levels of mechanical energy input, did not lead to a decrease in the wet weight of GMP or the size of glutenin particles. Confocal scanning laser microscopy of doughs revealed that shear processing produced a homogeneously distributed dough protein matrix, however, the GMP extracted from the sheared dough showed the presence of large clusters of particles. On the other hand, z-blade mixing led to disruption of these particles. Thus the type of deformation applied during dough processing is of crucial importance and in designing new equipment for dough processing the principles of different types of shear should be considered.

Interaction of water unextractable solids and xylanase with gluten protein: effect of wheat cultivar

A previously proposed explanation for the change in gluten properties on addition of pentosans to doughs was based on data for only one wheat cultivar. Using three wheat cultivars, Scipion, Soissons and Amazon, differing in technological quality from weak to strong we have obtained results that support the previous explanation. In addition to standard techniques for characterizing gluten and glutenin macropolymer (GMP) yield, composition and properties, a new technique (particle size analysis) was applied that provides further detail on GMP particle size distribution. For each of the three wheat cultivars the effect of WUS and xylanase on gluten and GMP yield, composition and properties followed the trend previously observed. However, WUS and xylanase affected gluten yield and properties more strongly for Scipion and Soissons than for Amazon. Amazon flour contains more protein and less pentosans. The analysis of GMP particles demonstrates that the volume surface average particle diameter D 3,2 of GMP particles from Amazon wheat is larger than those from Scipion and Soissons. Amazon has the ability to form larger and stickier particles. These factors may explain why the effects of pentosans and xylanase on gluten yield and properties are smaller for this wheat.

How gluten properties are affected by pentosans

During the wet separation of starch and gluten, both water extractable pentosans (WEP) and water unextractable solids (WUS) have a negative effect on gluten yield. Gluten properties are also affected: the gluten becomes less extensible. In comparison to the control, addition of WUS or WEP resulted in less gluten with a higher maximum resistance to extension ( R max ) and a smaller extensibility at maximum resistance ( E at R max ). The corresponding glutenin macropolymer (GMP) gel was more elastic, and the specific volume of the GMP particles was larger and their tendency to aggregate was lower. In contrast, the use of xylanase or ferulic acid (FA) resulted in a higher gluten yield and a larger E at R max of gluten. Here, the GMP was characterised by a more viscous gel structure, a smaller specific volume of the GMP particles and a larger tendency of GMP particles to aggregate. Correlations between gluten properties ( R max , E at R max ) and GMP particle properties ([ η ], K ′) were observed. Based on these observations, we propose a possible explanation for the effect of pentosans on gluten formation and properties. Both a physical effect and a chemical effect are involved. The physical effect is related to viscosity and likely also to depletion attraction between protein particles. The chemical effect is related to a FA-mediated effect and ‘controls’ the tendency of the particles to aggregate ( K ′). The contribution of physical and chemical effects leads to a partial agglomeration of GMP particles and shifts the GMP particle size distribution to a higher value. Since GMP particle properties could be directly related to gluten rheological properties, this explains the change in quality observed.

How gluten properties are affected by pentosans

During the wet separation of starch and gluten, both water extractable pentosans (WEP) and water unextractable solids (WUS) have a negative effect on gluten yield. Gluten properties are also affected: the gluten becomes less extensible. In comparison to the control, addition of WUS or WEP resulted in less gluten with a higher maximum resistance to extension (Rmax) and a smaller extensibility at maximum resistance (E at Rmax). The corresponding glutenin macropolymer (GMP) gel was more elastic, and the specific volume of the GMP particles was larger and their tendency to aggregate was lower. In contrast, the use of xylanase or ferulic acid (FA) resulted in a higher gluten yield and a larger E at Rmax of gluten. Here, the GMP was characterised by a more viscous gel structure, a smaller specific volume of the GMP particles and a larger tendency of GMP particles to aggregate. Correlations between gluten properties (Rmax, E at Rmax) and GMP particle properties ([η], K′) were observed. Based on these observations, we propose a possible explanation for the effect of pentosans on gluten formation and properties. Both a physical effect and a chemical effect are involved. The physical effect is related to viscosity and likely also to depletion attraction between protein particles. The chemical effect is related to a FA-mediated effect and 'controls' the tendency of the particles to aggregate (K′). The contribution of physical and chemical effects leads to a partial agglomeration of GMP particles and shifts the GMP particle size distribution to a higher value. Since GMP particle properties could be directly related to gluten rheological properties, this explains the change in quality observed. © 2004 Elsevier Ltd. All rights reserved.

Evidence that pentosans and xylanase affect the re-agglomeration of the gluten network

In the gluten-starch separation process gluten is formed first as a result of breakdown of the gliadin-glutelin structures during mixing followed by their re-agglomeration. To date the effect of pentosans and enzymes have not been studied separately. A simple modification of TNO Glutomatic system enables pentosans, enzymes, and other materials to be added after the mixing step allowing the effect of these additives to be studied separately. Using this technique, we observed that re-aggregation of gluten proteins starts immediately after the first mixing step during the dough dilution phase. Xylanase addition prior to dough mixing can lead to ‘overdose effects’ but these were not observed when xylanase was added later during the re-agglomeration phase. We were able to distinguish between physical and chemical effects of pentosans on gluten formation. The effect of water-extractable pentosans is only partly related to its viscosity, a ferulic acid (FA) related reaction is more important. Pentosans affect the affect the agglomeration by increasing the size of the glutenin macropolymer particles. When the water-extractable pentosan effect is prevented by xylanase or FA addition, aggregation during dilution is more extensive and the glutenin macropolymer has a lower average particle size with a resulting difference in gluten rheology.

Understanding the link between GMP and dough: from glutenin particles in flour towards developed dough

Clear correlations exist for glutenin macropolymer (GMP) quantity and rheological properties vs. wheat quality and dough rheological properties, but real insight in understanding these links is still missing. The observation that GMP consists of glutenin particles opens up new possibilities to reveal the underlying mechanism linking glutenin network properties with dough preparation. GMP was isolated from flour of three wheat varieties: Estica, Soissons and Baldus, strongly varying in their mixing requirements (expressed as time-to-peak, TTP). Decrease of GMP quantity and G′ vs. mixing energy was confirmed. More detail was obtained by studying the changes in GMP particles when mixing flour into dough. Mixing leads to a decrease in the average size of the particles. Interestingly, the TTP coincided with the work-input at which all particles just became soluble in SDS. At TTP, the average size of the GMP particles was the same for each variety. During mixing particles lost their globule shapes and appeared ruptured. Particle size analysis confirmed that particles were still present near TTP. Analysis of the change in particle size vs. energy input using physical principles revealed the following: (1) mixing energy is the predominant actuator in decreasing GMP particle size; (2) the initial GMP particle size in flour strongly determines the practical mixing requirements; and (3) the derived mixing energy vs. GMP particle size relationship was shown to be applicable for both Mixograph and Farinograph mixing. Our results demonstrate that, for the flour samples used, glutenin particle size determines TTP and GMP rheology, showing that glutenin particle properties could be a new key to understand the link between GMP and dough properties. © 2003 Elsevier Ltd. All rights reserved.