Percentage Of Unextractable Polymeric Protein Research Articles

Novel parameters characterizing size distribution of A and B starch granules in the gluten network: Effects on dough stability in bread wheat

Our study on six wheat genotypes has revealed strong interaction between gluten and starch to affect dough stability. To establish gluten-starch interaction and its roles in dough stability, we randomly selected 16 wheat genotypes and investigated the physicochemical properties of gluten and starch. The manner in which the starch granules occupied available space in gluten network was quantitatively analyzed using gluten lacunarity and proportion of different sized A-type and B-type starch granules. Positive correlations were found between the morphological attributes (B/A/Lacunarity, B/Lacunarity) and dough stability. The correlation coefficient between B/A/Lacunarity and dough stability was highest, followed by the percentage of unextractable polymeric protein (UPP%), B/Lacunarity and dough stability. Dough mixing properties were strongly affected by gluten-starch interactions, as indicated by novel parameters. Whereas the effect of gluten on its own did not provide any evidence to suggest its concrete role in dough mixing properties because of the various genetic backgrounds.

N Partitioning between Gluten Fractions in a Set of Italian Durum Wheat Cultivars: Role of the Grain N Content.

Grain protein content constitutes a key quality trait for durum wheat end-products and may also impact grain protein composition. A total of sixteen durum wheat cultivars were analyzed in a field trial during two seasons at two nitrogen (N) levels to evaluate whether and to what extent the variation in total grain N was associated with variation in the quantity of the various protein fractions and grain quality parameters. Genotypic variation in grain N content correlated with the variation in the content of all three protein fractions, although the strength of the correlation with gliadin and albumin-globulin was higher than that with glutenins. Genotypic variation in gliadin and glutenin content was more tightly correlated with the variation in the sulfur (S)-rich protein groups than with the S-poor protein groups and subunits. The variation in the percentage of unextractable polymeric proteins (UPP%) among genotypes was independent of their glutenin allelic composition. The significant genotypic differences in UPP% and in the ratios between protein groups and subunits were not influenced by the corresponding variation in grain N content. The final grain N content can only account for part of the variation in quality parameters and in the partitioning of total grain N between protein fractions since genotypic differences other than grain N content also contribute to these variations.

Influence of gluten and starch granules interactions on dough mixing properties in wheat (Triticum aestivum L.)

Wheat flour dough can be regarded as a complicated mixture in which gluten forms a continuous three-dimensional network filled with starch particles. Previous studies have concentrated on the influences of either gluten or starch alone on the rheological properties of wheat dough and found the components of gluten and starch responsible for the dough behavior, including use of parameters, such as the content of protein, wet gluten and amylose, for the evaluation of wheat quality. Earlier, in our study of six wheat materials, significant differences were observed in size distribution of starch granules affecting the dough mixing behavior. However, to our knowledge little research has been undertaken on the association of starch granules and protein networks on dough formation. In this study, the six wheat lines were further explored for the effect of gluten-starch interactions on dough properties. In order to achieve this, the wheat flour samples were quantified for gluten secondary structures, percentage of unextractable polymeric protein, high- to low-molecular-weight glutenin ratio, gluten micro-structure, number distribution of starch granules and moisture distribution in dough samples. A/Lacunarity (A-type starch granule content divided by lacunarity of gluten network) and B/A/Lacunarity (B- to A-type starch granule ratio divided by lacunarity) were proposed to characterize the level of interactions of differently sized starch granules to gluten protein networks in the dough. Results showed that dough stability time increased with the increase of B/A/Lacunarity, as closely packed dough, due to close interaction between starch granules and gluten, exhibited greater dough stability. Application of A/Lacunarity and B/A/Lacunarity as novel indicators is proposed to further elucidate precise influences between starch and gluten for better evaluation of dough properties.

Can nitrogen fertilization be used to modulate yield, protein content and bread-making quality in Uruguayan wheat?

Genotype and environment jointly determine yield and bread-making quality of bread wheat, being possible modulators for these characters. Eleven cultivars were grown at three different nitrogen regimes combining quantity and timing of nitrogen availability for two years; yield, grain protein concentration and Alveograph parameters were determined. Amount and size distribution of proteins were measured using Size Exclusion-High Performance Liquid Chromatography. The results showed year to be the most important determinant of percentage of unextractable polymeric protein in total polymeric protein (%UPP) and yield, while nitrogen regime determined grain protein concentration, the total amount of SDS-extractable and -unextractable proteins, Alveograph W and L. High nitrogen regime generated three types of responses among the cultivars; i) an increase of yield and grain protein concentration, ii) an increase in grain protein concentration but a reduction in %UPP, and iii) an increase in %UPP. For group ii, a low nitrogen regime at early stages but high at later stages was preferential, while for other groups, a high nitrogen regime during the whole season was the most beneficial. This study showed that it is possible to modulate yield and quality in bread wheat by the nitrogen regime, although an understanding of genotype-environmental relationships is necessary.

Effects of HMW-GS at Glu-B1 locus on the polymerization of glutenin during grain development and on the secondary and micro-structures of gluten in wheat (Triticum aestivum L.)

The viscoelastic properties of wheat dough are due mainly to the structure of gluten and interactions within the protein complex. We determined the effects of high-molecular-weight glutenin subunit (HMW-GS) on the polymerization of glutenin during grain development and on the secondary and micro-structures of gluten, using Xinong1718 and its four near-isogenic lines (NILs). The polymerization of glutenin was monitored based on the percentage of unextractable polymeric protein (%UPP). Xi1718-3 with the superior allele Bx17 + By18 exhibited a rapid increase in %UPP five days earlier than the other lines with variations at Glu-B1, thereby obtained the highest %UPP at maturity. The secondary structures, such as the proportion of β-sheets and the α-helix/β-sheet ratio differed significantly among the NILs. The micro-structure of gluten in NILs varied in terms of the pore size distribution and cross-linkage patterns. Significant correlations were found between %UPP with the β-sheet content and α-helix/β-sheet ratio, so these secondary structures could also be used as indicators of wheat flour quality.

Effects of Glu-1 Deletion on Size Distribution of Glutenin Polymeric Protein and Dough Properties in Common Wheat

The relationship between the HMW-GS and LMW-GS components and the size distribution of glutenin polymeric protein and dough properties were studied using Glu-1 normal and deletion lines, which provides a foundation for investigating the potential of Glu-1 deletion line in quality improvement of wheat. In the 20 hard white winter wheat lines tested, one was Glu-A1 deletion line, five were Glu-D1 deletion lines, and three were Glu-A1 and Glu-D1 double-deletion lines. Flour protein contents of the lines tested ranged from 13.39% to 14.12% with no significant difference between each other and between deletion and non-deletion groups. In Glu-1 deletion lines, the high molecular weight glutenin subunits/low molecular weight glutenin subunits ratio(HMW/LMW), content of SDS unextractable polymeric protein(UPP), and percentage of UPP(%UPP) were significantly lower than those in non-deletion lines. However, the glutenin/gliadin ratio(GLU/GLI) was similar in all genotypes, with no significant difference between deletion and non-deletion groups. Deletion at Glu-1 resulted in a significant decrease of dough elasticity and a significant increase of dough extensibility. Several Glu-1 deletion lines were characterized with medium gluten strength and excellent extensibility, suggesting that the size distribution of glutenin polymeric protein and dough properties were affected by both allelic composition and quantity of glutenin subunits. These results indicate that Glu-1 deletion lines can be used to improve dough extensibility and processing quality of common wheat.

Post-anthesis heat and a Gpc-B1 introgression have similar but non-additive effects in bread wheat.

High temperatures during grain filling can reduce the yield of wheat and affect its grain protein concentration. The Gpc-B1 locus of wheat also affects grain protein concentration, but it is not known whether its effects interact with those of heat. The aim of this study was to investigate the effects of high temperature in lines with and without functional (high-protein) alleles at Gpc-B1. A highly replicated experiment was conducted in a glasshouse under control conditions (24/18°C, 14/10h day/night), with half of the plants of each line or cultivar put into a heat chamber (37/27°C, 14/10h day/night) at 15 days after anthesis for 3 days. Backcross derivatives with the Gpc-B1 introgression segment differed from their recurrent parents more than those without that segment. In some respects, the effects of the Gpc-B1 introgression were similar to those of the heat treatment: both could accelerate peduncle senescence, increase grain protein content and increase the percentage of unextractable polymeric protein. Unlike the heat treatment, Gpc-B1 did not reduce grain weight, indicating that factors that hasten senescence do not necessarily limit grain size. The presence of the Gpc-B1 segment did not exacerbate the effects of heat stress on any trait.

Amount and Size Distribution of Monomeric and Polymeric Proteins in the Grain of Organically Produced Wheat

ABSTRACTIn the present study, we evaluated 444 organically grown wheat genotypes for the amount and size distribution of polymeric proteins by size‐exclusion HPLC. The investigated genotypes were divided into six genotype groups—selection, spelt, old cultivar, primitive, landrace, and cultivar—and these were grown in four different locations, namely, Alnarp, Bohuslän, Gotland, and Uppsala in Sweden. The results showed that the percentage of unextractable polymeric proteins in total polymeric proteins (%UPP) and percentage of large unextractable polymeric proteins in total polymeric proteins were higher in the cultivar group as compared with the rest of the investigated genotype groups. The amounts of total extractable polymeric proteins (TOTE) and total unextractable polymeric proteins were low in cultivars and selections, respectively. Spring wheat grain was found to have a significantly higher amount of all protein fractions as compared with winter wheat. The genotype Kenya was found to belong to both groups of the 20 genotypes with the highest TOTE and %UPP. Thus, the genotype Kenya might be of relevance for consumption and future breeding to improve the breadmaking quality of organically produced wheat.

Towards the understanding of bread-making quality in organically grown wheat: Dough mixing behaviour, protein polymerisation and structural properties

Achieving high quality of organic bread is a major objective of organic wheat production. The aim of the present study was to understand the mechanisms related to bread-making quality in organically grown wheat genotypes from a diverse background. Fifty one organically grown winter and spring wheat genotypes were evaluated for percentage of unextractable polymeric proteins in total polymeric proteins (%UPP) in flour and dough, mixing behaviour and structural properties. The results showed a large variation in genotypes for %UPP in flour, changes in %UPP at mixing, mixing parameters and structural properties. Genotypes with high %UPP in flour and low change in %UPP at optimum mixing were; Agron, Hjelmqvist 6357 blå and Effrada. The light microscopy (LM) and confocal laser scanning microscopy (CLSM) results confirmed that genotypes with high %UPP in flour and a low change at optimal mixing resulted in a more extended protein network (continuous and interconnected) at mixing as compared to the other genotypes. Genotypes with good mixing properties as to the mixograph analyses were; Diamant ax, Lantvete Gotland 4496 spelt, Erbe brun and Jacoby 59. The present study shows the presence of opportunities to select genotypes suitable for cultivation and breeding of bread wheat for organic production.

Influence of water deficit on durum wheat storage protein composition and technological quality

Two durum wheat ( Triticum durum Desf.) cultivars (Simeto and Ofanto) were grown in field trials in Foggia (Southern Italy), under two water regimes and in three cropping seasons, to evaluate the influence of water regime on grain protein composition in relation to technological quality. On grain samples, the following quality analyses were performed: protein and gluten content, gluten index and SDS test. Furthermore, different protein fractions were evaluated: gliadins; glutenins, high molecular weight subunits (HMW-GS) and low molecular weight subunits (LMW-GS) of the larger glutenin polymers; percentage of unextractable polymeric proteins (%UPP). Two-dimensional gel electrophoresis (2D) of glutenins was also performed on selected samples. A year-on-year variation in gluten index was observed and its values were positively correlated ( r = 0.71**) with the number of days with maximum temperature ranging from 30 to 35 °C during grain filling. This was consistent with an increase in glutenin fractions. Between the investigated cultivars, Simeto showed better technological performance and higher glutenin content, HMW-GS/LMW-GS ratio and %UPP. Water deficit was found to affect technological quality and protein composition differently depending on the timing of stress occurrence. An increase in protein content and in HMW-GS/LMW-GS ratio, consistent with a decrease in grain yield, was observed when water deficit occurred throughout the growing season. When a terminal water stress occurred in grain filling an improvement in gluten strength was observed consistently with an increase in the amount of glutenin macropolymers associated to a general modulation of HMW-GS and LMW-GS levels, as indicated by 2D analyses. Probably water deficit associated to high temperature stress which generally occurs under Mediterranean environments during grain filling, may have caused a higher aggregation level of glutenin subunits that was reflected in an improvement of technological quality.

Sponge and dough bread making: genetic and phenotypic relationships with wheat quality traits

The genetic and phenotypic relationships among wheat quality predictors and sponge and dough bread making were evaluated in a population derived from a cross between an Australian cultivar 'Chara' and a Canadian cultivar 'Glenlea'. The genetic correlation across sites for sponge and dough loaf volume was high; however, phenotypic correlations across sites for loaf volume were relatively low compared with rheological tests. The large difference between sites was most likely due to temperature differences during grain development reflected in a decrease in the percentage of unextractable polymeric protein and mixing time. Predictive tests (mixograph, extensograph, protein content and composition, micro-zeleny and flour viscosity) showed inconsistent and generally poor correlations with end-product performance (baking volume and slice area) at both sites, with no single parameter being effective as a predictor of end-product performance. The difference in the relationships between genetic and phenotypic correlations highlights the requirement to develop alternative methods of selection for breeders and bakers in order to maximise both genetic gain and predictive assessment of grain quality.

Relationship of polymeric proteins with pasting, gel dynamic- and dough empirical-rheology in different Indian wheat varieties

The protein characteristics of flours from fifteen Indian wheat varieties were studied and related to pasting, gel viscoelasticity and dough properties. The analysis of polymeric proteins showed glutenins, gliadin and glutenin to gliadin ratio ranged between 28.14 and 40.44%, 45.33 and 55.83% and 0.50 and 0.89, respectively. Paste breakdown was low in flours with higher protein content. Viscoelastic properties of flour gels from different varieties showed significant variation and were dependent more on protein than amylose content. The gelation behavior of cooked pastes measured during cooling and holding at 10 °C was explained by an equation. Dynamic moduli of gels were positively correlated with total protein content and negatively correlated to the percentage of unextractable polymeric protein (UPP). Dough strength was positively related to UPP and glutenin content.

Effect of heat stress on wheat proteins during kernel development in wheat near-isogenic lines differing at Glu-D1

Two near-isogenic lines of the wheat variety Lance having Glu-D1a (HMW-GS 2 + 12) and Glu-D1d (HMW-GS 5 + 10) were subjected to several regimes of heat stress. In 2001, the temperature regimes were (i) 20/16 (day/night, °C) from planting to maturity, (ii) 20/16 except for a 3-day heat treatment of 35/20, 25 days after anthesis and (iii) 20/16 until 25 DAA, after which plants were subjected to 40/25 until maturity. In 2002, treatments (i) and (iii) were the same while treatment (ii) used a temperature of 40/25 °C for 3 days at 25 DAA. Seed was collected at 3-day intervals starting from 16 days after anthesis and analyzed for protein composition by SE-HPLC. The line with the Glu-D1d allele showed an earlier polymerization of glutenin than its allelic counterpart and a higher molecular weight of glutenin at maturity, this being deduced from measurements of the percentage of unextractable polymeric protein. It is postulated that the timing and rate of glutenin polymerization, and the timing of high temperature application may be the key factors contributing to an explanation of the effect of heat stress on functionality.

Protein Composition‐Functionality Relationships for a Set of Argentinean Wheats

ABSTRACTRelationships between flour functional properties and protein composition were studied using a set of 138 Argentinean wheat samples. Among different protein groups, the incremental increase of gliadin with increasing grain protein content was highest followed by polymeric protein with albumin‐globulin content much lower. Functional properties could be divided into two groups based on dependence on protein composition. Properties such as dough extensibility and bake test loaf volume correlated highly with the percentage of polymeric protein in the grain. Properties such as mixograph dough development time were best correlated with the percentage of polymeric protein in the protein (PPP). Alveograph tenacity showed no significant dependence on PPP. as found previously for extensigraph maximum resistance, but it was correlated with the percentage of unextractable polymeric protein in the protein. Energy (W) appeared to be a more useful alveograph parameter for predicting flour quality.

Seasonal effects on storage proteins and gluten strength in four Swedish wheat cultivars

AbstractWeather variations in Sweden result in differences in the bread‐making quality of wheat. This study investigated whether the variation in bread‐making quality caused by yearly weather fluctuations could be explained by variation in protein composition, amount of storage proteins, protein subunits and protein groups, and relative amount and size distribution of polymeric proteins. Four spring wheat (Triticum aestivum L) cultivars grown in Sweden during three different years were investigated. Bread‐making quality and gluten strength were measured using baking and glutograph tests. SDS‐PAGE, SE‐HPLC, RP‐HPLC and ELISA were applied for investigation of protein composition, amount of storage proteins, protein subunits and protein groups, and relative amount and size distribution of polymeric proteins. The bread volume within cultivars varied depending on the cultivation year. The highest gluten strength was found in 1994 and the weakest in 1991. Variation in composition or relative amount of specific storage proteins, protein subunits or protein groups could not explain the variation in gluten strength between years. Instead, a significant relationship was found between the cultivation year and the percentage of unextractable polymeric protein in the total polymeric protein. The percentage of unextractable polymeric protein in the total polymeric protein was found to be highest during years when gluten strength was also high.© 2002 Society of Chemical Industry

Protein Composition for Pairs of Wheat Lines with Contrasting Dough Extensibility

Factors determining dough extensibility have been studied using two pairs of advanced breeding lines grown at five different locations in which individual lines of each pair differed in extensibility. For one pair (DD118 and RAC704), the differences related mainly to variations in the percentage of flour polymeric protein. On the other hand, the second pair (VF304 and RAC746) did not show a significant difference in this parameter, making them suitable for the study of other factor(s) that influence extensibility, presumably genotypic in nature. The percentage of unextractable polymeric protein (UPP) differed appreciably between these two lines at all sites. This suggests that an important genotypic factor associated with extensibility is the molecular weight distribution of the protein.