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 (D_4.3) 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, D_4.3, 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 Transglutaminase on Properties of Glutenin Macropolymer and Dough Rheology

The 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.     

Depolymerization of the Glutenin Macropolymer During Dough Mixing: I. Changes in Levels,Molecular Weight Distribution,and Overall Composition

Changes in the amounts, molecular weight distributions, and levels of major groups of subunits in the glutenin macropolymer (GMP) of doughs during mixing were investigated. The GMP (gel protein) is the unreduced fraction of gluten protein that remains as a layer on top of the starch after extraction of SDS-soluble proteins and centrifugation. Experiments involved doughs prepared from flours derived from one weak and one strong cultivar and lines derived from cv. Olympic that were null for specific high molecular weight glutenin subunits (HMW-GS). During mixing, the amount of GMP decreased; the major changes occurred before peak mixing time (MT, achievement of peak resistance). In addition, the average apparent molecular weight of GMP (determined by both size-exclusion HPLC and multilayer gel electrophoresis) decreased during mixing, but in this case, the major changes were seen later in the mixing process, during dough breakdown. Even after extensive mixing, polymers and oligomers were released, not free glutenin subunits. During dough breakdown, the composition of GMP also changed, such that the proportion of HMW-GS decreased but β-amylases/D low molecular weight glutenin subunits (LMW-GS) increased. Changes in the total amounts of other LMW-GS typically were smaller with a decrease in the proportion of B subunits and an increase in the proportion of C subunits. The major changes in GMP composition were observed after peak MT (peak resistance) occurring earlier and to a greater extent in the weaker dough. Our results suggest that dough breakdown during mixing may be triggered by loss of HMW-GS, leading to changes in the molecular weight distribution and composition of the disulfide-bonded GMP.     

Depolymerization of the Glutenin Macropolymer During Mixing: II. Differences in Retention of Specific Glutenin Subunits

The depolymerization of individual high and low molecular weight (HMW and LMW, respectively) glutenin subunits (GS) from the glutenin macropolymer (GMP) in doughs during mixing was investigated by reversed-phase (RP) HPLC and SDS-PAGE. Cultivars with different dough strengths, as well as lines null for specific HMW-GS and biotypes differing at individual HMW-GS and LMW-GS encoding loci, were studied. During mixing, the proportion of total HMW-GS in GMP decreased, and the ratios of different subunits in the GMP in doughs changed. There was a loss of chromosome 1B- and 1D-encoded x-HMW-GS, while the relative proportions of y-HMW-GS (among HMW-GS) increased. Changes in 1B subunits occurred first, while most of the changes in 1D HMW-GS content occurred during dough breakdown. Changes were more pronounced for doughs of weak to average strengths than for stronger doughs. RP-HPLC analysis demonstrated a consistent increase in the retention times (surface hydrophobicity) of chromosome 1D-encoded HMW-GS but not of other HMW-GS or LMW-GS during mixing. SDS-PAGE and RP-HPLC demonstrated that specific B subunits, typically those with lower hydrophobicity, were selectively depolymerized from the GMP during dough breakdown, while the proportions of specific C subunits, typically those with greater hydrophobicity, increased. Similar trends were seen in analyses of several pairs of biotypes differing at single LMW-GS encoding loci, although there were slight differences in the depolymerization behavior of wheats with different allelic compositions. The results suggest that dough breakdown may be triggered by the loss of specific HMW-GS from the GMP, and a structural hierarchy may exist for different LMW-GS within glutenin in doughs.     

Relationship between endogenous protein disulfide isomerase family proteins and glutenin macropolymer

The effects of endogenous protein disulfide isomerase (PDI) family proteins on the properties of gluten proteins in dough during breadmaking were determined using bacitracin, an inhibitor of PDI. Bread loaf volume in the presence of bacitracin was increased to 118% of that in the absence of bacitracin. The addition of bacitracin caused a decrease in the extension tolerance of the dough. The amount of sodium dodecyl sulfate (SDS)-insoluble glutenin macropolymer (GMP) in dough decreased to approximately 70% of that in flour during the 20 min of mixing for doughmaking. The addition of bacitracin to dough caused a dramatic GMP decrease, corresponding to ～20-30% of that in flour during the 20 min of mixing. The decrease in GMP was compensated by an increase in SDS-soluble glutenin polymer. Taken together, these results suggest that the endogenous PDI family proteins in flour suppress the depolymerization of GMP during dough mixing.     

Immunocytochemical Localization of Gluten Proteins Uncovers Structural Organization of Glutenin Macropolymer

The content and composition of the disulfide‐bonded glutenin macropolymer has been shown to influence dough properties, although its structural organization is poorly characterized. The structure of the glutenin macropolymer in dough was studied using an immunolocalization transmission electron microscopy (TEM) technique by localizing gliadins, low molecular weight glutenin subunits (LMW‐GS), and high molecular weight glutenin subunits (HMW‐GS) in sections of dough using antibody probes selective for each of the three classes of gluten polypeptides. Distinct differences in the distribution patterns of gliadins, LMW‐GS, and HMW‐GS were observed, which suggests that proteins have different roles in the structural organization of the gluten matrix. On the basis of the observed distribution of the proteins in dough, it is speculated that gliadins, which are randomly distributed as individual particles, fill space within the glutenin macropolymer; LMW‐GS, which are present as clusters, are speculated to form aggregated branch structures; and HMW‐GS, which are present as chains, are speculated to form a network from which the LMW‐GS branches are formed. Changes in the distribution of gliadins, LMW‐GS, and HMW‐GS in dough during mixing were also noted. Such an arrangement supports previous biochemical evidence which has established that gliadins, LMW‐GS, and HMW‐GS have specific roles in the structural organization of the glutenin macropolymer in doughs.     

Glutenin Macropolymer in Salted and Alkaline Noodle Doughs

An attempt was made to understand the physicochemical attributes that are the basis of physical differences between alkaline and salted noodle doughs. Flour and dough properties of one soft and three hard‐grained wheat cultivars were observed. Doughs were made with either sodium chloride or sodium carbonate. Each formulation variant was tested at both high and low water additions. Samples for glutenin macropolymer (GMP) isolation were taken at selected noodle dough processing stages. When a 1.67% w/v Na₂CO₃ solution was used for mixograph testing, dough characteristics were radically altered and differences between cultivars were masked. In lubricated squeezing flow (LSF) testing, hard wheat noodle doughs had significantly (P < 0.01) longer relaxation times and higher % residual force values than soft wheat doughs in both the salted and alkaline variants. LSF maximum force and biaxial viscosity were significantly higher in alkaline doughs than salted. GMP extracted from alkaline doughs was gummy and sticky, and was more opaque than GMP from salted doughs. GMP weight decreased sequentially when extracted from samples taken in the active phase (mix, compound, sheet) of noodle dough processing and decreased more in alkaline doughs. GMP weight increased more after 24 hr of dough rest in salted doughs. GMP gel strength was noticeably higher in GMP extracted from alkaline doughs. After dough resting, alkaline GMP gel strength significantly increased, whereas it decreased in GMP from salted doughs, suggesting a role for GMP in the increased stiffness of alkaline noodle doughs.     

灌水量对不同小麦品种籽粒品质、产量及土壤硝态氮含量的影响

选用强筋小麦济麦20和中筋小麦泰山23两个品种，在大田条件下设置不灌水（0mm）、灌水180mm，240mm和300mm4个处理，研究了灌水量对籽粒品质和产量及土壤硝态氮含量的影响。结果表明，灌水180mm和240mm的处理比不灌水和灌水300mm的处理提高了强筋小麦济麦20的籽粒谷蛋白含量、谷蛋白含量／醇溶蛋白含量比值（谷／醇比值）、谷蛋白大聚合体（GMP）含量和湿面筋含量，延长了面团稳定时间，改善了籽粒品质；中筋小麦泰山23的不灌水处理的籽粒蛋白质含量高于灌水180mm，240mm和300mm的处理，但是GMP含量、湿面筋含量和面团稳定时间各处理间无显著差异。两品种的籽粒产量均以灌水240mm的处理最高，但泰山23灌水180mm的处理与灌水240mm的处理无显著差异。随灌水量增加，土壤中的硝态氮向深层土壤的淋溶增加。本试验条件下，综合考虑品质、产量和土壤中硝态氮的淋溶，济麦20和泰山23可供生产中参考的灌水量分别为180～240mm和180mm。     

两种酶制剂对非发酵面团冻融循环后品质的影响

为了探究酶制剂对非发酵面团在冻融循环后的品质的影响,该文比较了2种酶制剂转谷氨酰胺酶(TGase)与木聚糖酶(xylanase)对非发酵面团冻融品质的改良效果。结果表明,与对照组相比,添加转谷氨酰胺酶和木聚糖酶均能改变冻融后面团蛋白各组分的含量。添加转谷氨酰胺酶使醇溶蛋白以及谷蛋白含量显著下降(P0.05)、谷蛋白大聚合体含量有所上升。添加木聚糖酶则使醇溶蛋白含量上升,使谷蛋白含量显著降低(P0.05)。转谷氨酰胺酶对面团中戊聚糖含量影响不显著(P0.05),而添加木聚糖酶使面团中可溶性戊聚糖含量显著上升(P0.05)。转谷氨酰胺酶的添加加速了冻融循环后非发酵面团的失水,木聚糖酶则显著降低了其失水率(P0.05)。除在10 g/kg转谷氨酰胺酶显著降至1.32 ms外,弛豫时间T2(1)基本维持在1.75 ms,而弛豫时间T2(2)均有所减小;添加转谷氨酰胺酶后,深层结合水相对含量呈逐渐上升趋势;而木聚糖酶则反之。木聚糖酶使冻融面团强韧性与对照组相比显著增强(P0.05),剪切力小幅下降,硬度显著下降(P0.05);与转谷氨酰胺酶相比,木聚糖酶更能缓解冻融面团的质构劣变;转谷氨酰胺酶改善冻融熟面坯的黏性、弹性与内聚性,木聚糖酶则改善"硬度上升,弹性下降"的劣变现象。在改善冻融面团流变特性方面,转谷氨酰胺酶效果更为显著(P0.05)。因此,添加转谷氨酰胺酶与木聚糖酶均能在一定程度上改善冷冻非发酵面团在冻融条件下的品质劣变,但它们的作用方面有所差异。研究结果为两者能够在冷冻非发酵面制品中被广泛地应用提供理论基础。     

Solubilization of Arabinoxylans from Isolated Water-Unextractable Pentosans and Wheat Flour Doughs by Cell-Wall-Degrading Enzymes

Water-unextractable pentosans (WUP) isolated from the flours of three wheat cultivars (Apollo, Soissons, Thésée) were treated with enzymes to solubilize the arabinoxylans. The water-unextractable arabinoxylans from the three cultivars had similar susceptibility to solubilization by enzymes: Grindamyl S 100 (GS100), a commercial preparation for baking, rich in pentosanase activities that originated from an Aspergillus niger culture; and three endoxylanases (E1, E2, E3), an arabinofuranosidase (Af), a β- glucanase (βG), and a ferulate esterase (FAE) purified from GS100. A cellulase (C) and a pure endoglucanase (eG) from Trichoderma reesei were also used. GS100 was able to solubilize high molecular weight arabinoxylans (HMWAX) from WUP that markedly enhance the viscosity of the reaction mixture supernatants. The endoxylanase E1 was responsible for this solubilizing activity of GS100, whereas E2 and E3 made only a very low contribution. Combining E1 with FAE led to a limited increase in the arabinoxylan-solubilizing effect. Also, enzymes hydrolyzing cellulose and β-glucans slightly improved the arabinoxylan solubilization from WUP when combined with GS100 or E1, but produced arabinoxylans of lower intrinsic viscosity. Similar effects of the enzymes were observed on arabinoxylan solubilization when applied to dough instead of isolated WUP.     

Correlation of Quality Parameters with the Baking Performance of Wheat Flours

The baking performance of a set of flours from 13 wheat cultivars was determined by means of two different microscale baking tests (10 g of flour each). In the micro‐rapid‐mix test the dough was mixed for a fixed time at a high speed, whereas the microbaking test used mixing to optimum dough consistency in a microfarinograph. Quality parameters such as sedimentation value, crude protein content, dough and gluten extension data, and microfarinograph data were also determined. Finally, quality‐related protein fractions (gliadins, glutenins, SDS‐soluble proteins, and glutenin macropolymer) were quantitated by extraction/HPLC methods with reversed‐phase and gel‐permeation columns. All quality parameters were correlated with the bread volumes of both baking tests. The results demonstrated that the microbaking test (adapted mixing time) was much more closely related to the quality parameters than the micro‐rapid‐mix test (fixed mixing time), which hardly showed any correlation. Among the standard quality parameters, only the crude protein content showed a medium correlation with the bread volume of the microbaking test (r = 0.71), whereas the contents of gliadins (r = 0.80), glutenins (r = 0.76), and glutenin macropolymer (r = 0.80) appeared to be suitable parameters to predict the baking performance of wheat flour. All other quality parameters were not or were only weakly correlated and unsuitable for predicting baking performance.     

水氮耦合对强筋冬小麦子粒蛋白质和淀粉品质的影响

在高肥力条件下,研究水氮耦合对小麦子粒产量、蛋白质含量及组成、蛋白质质量、淀粉含量及组成和淀粉品质的影响。结果表明,无论施氮与否,灌水均显著提高小麦子粒产量,同时显著降低子粒粗蛋白、单体蛋白及湿面筋含量;但不同灌水量间(W1、W2、W3)差异不显著。在低灌水频次(W0、W1)条件下,施氮具有明显的增产效应;而高灌水频次(W2、W3),施氮的增产效应不显著。随着灌水次数增加,谷蛋白总量保持稳定,而谷蛋白组分产生了显著的变化,其中可溶性谷蛋白含量呈上升趋势,不溶性谷蛋白含量和谷蛋白聚合指数呈下降趋势,粉质仪参数(形成时间和稳定时间)也呈下降趋势。小麦子粒蛋白质含量及组分和子粒品质均因施氮(N.168.kg/hm2)而有不同程度的提高,其中非面筋蛋白(清蛋白和球蛋白)的增加幅度高于面筋蛋白(醇溶蛋白和谷蛋白),可溶性谷蛋白增加幅度高于不溶性谷蛋白,即降低了谷蛋白聚合指数。水氮对子粒的淀粉含量及其组成的影响存在明显的交互效应。在不施氮肥条件下,随灌水次数增加,支链淀粉和总淀粉含量呈上升趋势;施氮条件下,各灌水处理(W1、W2、W3)的总淀粉和支链淀粉含量均显著高于不灌水处理(W0),但各灌水处理间差异不显著。随灌水次数增加,直链淀粉含量和直/支比均呈下降趋势,黏度仪指标(峰值黏度、稀值、最终黏度和反弹值)均呈上升趋势。施氮在低灌水频次(W0、W1)条件下促进支链淀粉的合成,同时降低直链淀粉含量和直/支比;高灌水频次(W2、W3)条件下则相反。     

Accumulation of High‐Molecular‐Weight Glutenin Subunits in Superior and Inferior Grains of a Winter Wheat,Yangmai 158

The difference in accumulation of high‐molecular‐weight glutenin subunits (HMW‐GS) in superior (basal) and inferior (distal) grains results in the nonuniformity of grain quality in a winter wheat (Triticum aestivum L. ‘Yangmai 158’). The HMW‐GS accumulation and glutenin macropolymer (GMP) content were studied in superior and inferior grains during the grain‐filling period. Compared with inferior grains, HMW‐GS was formed earlier and total accumulation amount was higher in superior grains. The total HMW‐GS content was higher in superior grain than inferior grain, except at maturity. For individual HMW‐GS types, the accumulation and content of subunit 7 were the highest, followed by subunit 12, and those of subunit 8 were the lowest, followed by subunit 2 in superior grain. In contrast, the accumulation and content of subunit 7 at maturity were significantly higher than subunit 8 but similar between subunit 2 and subunit 12 in inferior grain. Moreover, the accumulation of subunit 7 and 12 in superior grain was significantly higher than in inferior grain. However, compared with the inferior grain, the GMP accumulation was higher but content was lower in superior grain at maturity.     

播期对小麦籽粒储藏蛋白及加工品质的影响

为明确播期对四川中、弱筋小麦储藏蛋白组分和加工品质的影响,以指导该地区专用型中、弱筋小麦生产,本试验以4个中、弱筋小麦品种为材料,设置早播（B1）、中播（B2）和晚播（B3）3个处理开展两年两点试验。结果表明,随着播期的推迟,中、弱筋小麦品种的谷蛋白、醇溶蛋白组分含量在崇州点增加,而仁寿点总体呈先降后升的变化趋势;储藏蛋白组分比例在不同品种间变化差异较大。两种筋型小麦的粗蛋白、湿面筋含量和沉降值在早播和晚播时高于中播,形成时间、稳定时间、粉质质量指数在晚播时高于早、中播,弱化度在崇州点随播期推迟显著降低,在仁寿点则先降后升。相关性分析表明,谷蛋白大聚合体（GMP）、高分子量谷蛋白亚基（HMW-GS）和总谷蛋白（Glu）含量与加工品质性状相关性较强。主成分分析表明,HMW-GS、ω-醇溶蛋白（ω）、总醇溶蛋白（Gli）含量和高/低分子量谷蛋白亚基比（H/L）、（α/β-醇溶蛋白）/Gli[(α/β)/Gli]可概括蛋白组分的主要变化信息;沉降值、稳定时间、粉质质量指数、形成时间、湿面筋含量可概括加工品质性状的主要变化信息。综合来看,四川麦区中筋小麦适当推迟播期、弱筋小麦适当提前播期可使小...     

Role of Gluten and Its Components in Determining Durum Semolina Dough Viscoelastic Properties

Gluten was isolated from three durum wheat cultivars with a range in strength. Gluten was further fractionated to yield gliadin, glutenin and high molecular weight (HMW) and low molecular weight (LMW) glutenin subunits (GS). The gluten and various fractions were used to enrich a base semolina. Enriched dough samples were prepared at a fixed protein content using a 2‐g micromixograph. Mixing strength increased with addition of gluten. Dynamic and creep compliance responses of doughs enriched with added gluten ranked in order according to the strength of the gluten source. Gliadin addition to dough resulted in weaker mixing curves. Gliadin was unable to form a network structure, having essentially no effect on dough compliance, but it did demonstrate its contribution to the viscous nature of dough (increased tan δ). Source of the gliadin made no difference in response of moduli or compliance. Addition of glutenin to the base semolina increased the overall dough strength properties. Glutenin source did influence both dynamic and compliance results, indicating there were qualitative differences in glutenin among the three cultivars. Enrichment with both HMW‐GS and LMW‐GS increased overall dough strength. Source of HMW‐GS did not affect compliance results; source of LMW‐GS, however, did have an effect. The LMW‐2 proteins strengthened dough to a greater extent than did LMW‐1. Mechanisms responsible for dough viscoelastic properties are described in terms of reversible physical cross‐links.     

Effects of tyrosinase and laccase on oat proteins and quality parameters of gluten-free oat breads

Effects of a Trichoderma reesei tyrosinase (TYR) and a Trametes hirsuta laccase (LAC) on breadmaking performance of gluten-free oat flour were investigated by SDS-PAGE analysis of oat protein fractions, large deformation rheology, and microscopy of the doughs, as well as on the basis of specific volume and firmness of the gluten-free breads. TYR induced the formation of higher molecular weight proteins in the SDS-PAGE assay. Microscopical analysis showed more intensive protein aggregation in the TYR-treated dough than in the dough without TYR. TYR also increased the firmness of the dough, which was assumed to be because of the cross-linking of oat globulins. LAC did not affect the oat globulins. TYR alone, or together with a commercial Thermomyces lanuginosus xylanase (XYL), increased significantly the specific volume of the gluten-free oat bread. A combination of TYR and XYL also increased the softness of the bread, whereas a combination of LAC and XYL improved the specific volume but did not affect the softness of oat bread. The results thus indicate that cross-linking of oat globulins by TYR, especially with the addition of XYL, was beneficial for improving the texture of gluten-free oat bread.     

施氮量对不同品质类型小麦子粒蛋白质组分含量及加工品质的影响

选用强筋小麦济麦20、中筋小麦泰山23和弱筋小麦宁麦9号,利用反相高效液湘色谱（RP-HPLC）方法测定了施氮量对不同品质类型小麦子粒蛋白质组分含量和高分子量谷蛋白亚基（HMW-GS）、低分子量谷蛋白亚基（LMW-GS）含量的影响,并分析其与子粒加工品质的关系。结果表明,随施氮量增加,强筋小麦济麦20和中筋小麦泰山23的子粒蛋白质含量及各组分含量均呈先增加后降低的趋势,施氮量为N 240 kg/hm2时,蛋白质各组分含量较高,加工品质较好; 过量施氮抑制了HMW-GS合成,这是过量施氮导致强筋和中筋小麦子粒蛋白质品质变劣的原因之一。随施氮量增加,弱筋小麦宁麦9号子粒的蛋白质各组分含量显著增加,加工品质变劣。增施氮肥,3个品种的谷蛋白和醇溶蛋白含量的增加幅度显著高于清蛋白+球蛋白含量,这是施氮改善强筋和中筋小麦子粒加工品质的主要原因。济麦20和泰山23两品种的总蛋白质含量及醇溶蛋白含量无显著差异,但强筋小麦济麦20的谷蛋白含量、贮藏蛋白、HMW-GS、LMW-GS、谷蛋白大聚合体（GMP）含量及谷蛋白与醇溶蛋白含量的比值（Glu/Gli）和HMW-GS与LMW-GS含量的比值（HMW/LMW）高于中筋小麦泰山23,这是强筋小麦济麦20加工品质形成及其面团形成时间和稳定时间显著高于泰山23的重要原因。     

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 Multiple Substitution of Glutenin and Gliadin Proteins on Flour Quality of Canada Prairie Spring Wheat

The effect of genetic substitution of two to four glutenin and gliadin subunits from a Canada Prairie Spring (CPS) cv. Biggar BSR into Alpha 16, another CPS wheat line, was studied for rheological and baking quality. Results from double substitution showed that the presence of a gliadin component from Biggar BSR (BGGL) and low molecular weight glutenin subunit 45 (LMW 45) contributed to improved dough strength characteristics. Presence of BGGL in combination with high molecular weight glutenin subunit 1 (HMW 1) or 17+18 (HMW 17+18) also showed improved dough strength over control Alpha lines. When three or four protein subunits were substituted, even though improved quality performance was observed, it was associated with the negative effect of lowered flour water absorptions in spite of similar protein contents. The study confirms that LMW glutenins, as well as gliadins, play an important role along with HMW glutenins in wheat flour quality. CPS wheat lines with improved dough strength properties can be selected from the double substitution lines with the combination of BGGL/LMW 45 and BGGL/HMW 1.     

Effects of Genotype and Environment on Glutenin Polymers and Breadmaking Quality

Six genotypes of hard red spring (HRS) wheat were grown at seven environments in North Dakota during 1998. Effects of genotype and environment on glutenin polymeric proteins and dough mixing and baking properties were examined. Genotype, environment, and genotype‐by‐environment interaction all significantly affected protein and dough mixing properties. However, different protein and quality measurements showed differences for relative influences of genotype and environment. Total flour protein content and SDS‐soluble glutenin content were influenced more by environmental than genetic factors, while SDS‐insoluble glutenin content was controlled more by genetic than environmental factors. Significant genotypic and environmental effects were found for the size distribution of SDS‐soluble glutenins and between SDS‐soluble and SDS‐insoluble glutenins as well as % SDS‐insoluble glutenins. With increased flour protein content, the proportions of monomeric proteins and SDS‐insoluble glutenin polymers appeared to increase, but SDS‐soluble glutenins decreased. Flour protein content and the size distribution between SDS‐soluble and SDS‐insoluble glutenin polymers were significantly correlated with dough mixing properties. Environment affected not only total flour protein content but also the content of different protein fractions and size distributions of glutenin polymers, which, in turn, influenced properties of dough mixing. Flour protein content, % SDS‐insoluble glutenin polymers in flour, and ratio of SDS‐soluble to SDS‐insoluble glutenins all were highly associated with dough mixing properties and loaf volume.