Good Breadmaking Research Articles

The use of the species Triticum petropavlovskyi Udacz. et Migusch. to expand the genetic diversity of spring bread wheat

Background. The species Triticum petropavlovskyi Udacz. et Migusch. has a number of positive traits, but has rarely been used in breeding programs to improve bread wheat cultivars. The introgression of genetic material from this species into the Triticum aestivum L. gene pool will not only expand the genetic diversity of bread wheat with a set of traits valuable for breeders, but also help to analyze the expression of genes from T. petropavlovskyi in a new genetic environment. Materials and methods. Spring bread wheat lines L163 and L164 produced with the participation of bread wheat cv. ‘Voevoda’ and an accession of T. petropavlovskyi were target materials of the study. Conventional methods were applied to perform phenological, phytopathological, genetic, and bread quality evaluations. Statistical processing of the resulting data was carried out using the Agros-2.10 software. Results. L163 and L164 were studied for their morphological and phenological indicators, resistance to pathogens, productivity, and grain quality. Differences in a number of traits between the lines and the recipient cultivar were observed. The introgression of the T. petropavlovskyi genetic material into bread wheat showed both positive and negative effects on some agronomic characteristics. L163 was identified for its resistance to the pathogens of leaf rust and powdery mildew, and tolerance to cereal aphids. It combined high productivity with an increased grain protein content compared to the recipient cultivar. In addition, this line demonstrated good rheological properties of its dough. Conclusion. Merging genetic materials from T. petropavlovskyi and bread wheat cv. ‘Voevoda’ made it possible to produce lines with a set of positive characteristics. The selected line, L163, combined effective resistance to a number of diseases, high grain productivity, and good breadmaking qualities, so it was included in the breeding process.

Identification of traits underpinning good breadmaking performance of wheat grown with reduced nitrogen fertilisation.

Nitrogen fertiliser is the major input and cost for wheat production, being required to support the development of the canopy to maximise yield and for the synthesis of the gluten proteins that are necessary for breadmaking. Consequently, current high-yielding cultivars require the use of nitrogen fertilisation levels above the yield optimum to achieve the grain protein content needed for breadmaking. This study aimed to reduce this requirement by identifying traits that allow the use of lower levels of nitrogen fertiliser to produce wheat for breadmaking. A range of commercial wheat genotypes (cultivars) were grown in multiple field trials (six sites over 3 years) in the UK with optimal (200 kg Ha-1 ) and suboptimal (150 kg Ha-1 ) application of nitrogen. Bulked grain samples from four sites per year were milled and white flours were baked using three types of breadmaking process. This identified five cultivars that consistently exhibited good breadmaking quality when grown with the lower nitrogen application. Chemical and biochemical analyses showed that the five cultivars were characterised by exhibiting grain protein deviation (GPD) and high dough elasticity. It is possible to develop novel types of wheat that exhibit good breadmaking quality by selecting for GPD and high dough strength. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Historical grain yield genetic gains in Norwegian spring wheat under contrasting fertilization regimes

AbstractSpring wheat is currently dominating wheat production in Norway. The introduction of combine harvesting in the 1950s spurred breeding efforts to improve lodging and preharvest sprouting resistance, and to integrate good breadmaking quality in the locally adapted germplasm. Release of landmark cultivars Runar and Reno in the 1970s revitalized the country's production and marked the onset of modern wheat cultivation in Norway. Since that time, new cultivars have been developed but little is known about the genetic basis of the achieved yield gains. We collected 21 representative cultivars released since 1972 in Norway and tested them in a multiyear field trial including two fertilization rates: 75 and 150 kg ha–1 N. We assessed grain yield, plant height, heading, maturity, length of grain filling period, grain protein content, protein yield, aboveground biomass, harvest index, grain weight, test weight, grains per spike, grains per square meter, and spikes per square meter and their response to fertilization. We document an annual increase in grain yield of 17.8 kg ha–1 (0.34%), at both rates of N fertilization. None of the traits exhibited significant genotype × management interaction. Wheat breeding has led to the development of higher‐yielding cultivars with higher protein yield that mature later, have a prolonged grain‐filling period, and produce more grains per spike and grains per unit area.

Improving the Technological and Nutritive Properties of Gluten-Free Bread by Fresh Curd Cheese Enrichment

Replacing wheat flour in the breadmaking process is a technology challenge since the elimination of gluten has a strong influence on bread quality. Proteins addition are often used to form a protein network capable of mimicking gluten-like structure, giving to dough a foaming support. This study aimed to evaluate the potential of denatured whey proteins coming from fresh curd cheese addition, to strengthening gluten-free dough structure, enhancing the breadmaking performance. Curd cheese additions were tested (5% up to 20%, weight/weight) and the effect on dough rheology behavior and bread quality was evaluated. Findings obtained revealed that the technology and nutritional properties of the bread can be enhanced by curd cheese addition, and such effects should be related to the composition and functionality of denatured whey proteins. Considering higher levels of curd cheese (20%) tested, improvements on bread quality was observed, leading to a considerable increase in bread volume (73%), softness (65%), with a significant reduction on staling kinetics (70%), comparing with control bread. Additionally, an improvement in nutritional value in terms of proteins (80%) and minerals content (P—50.0%, Mg—6.0%, and Ca—360.3%) was obtained, which can give an additional contribution to the nutritional daily requirements of celiac patients. Linear correlations between dough rheology properties and bread quality attributes were found, supporting the good breadmaking performance obtained.

Effect of Glu‐D1 gene introgression and amylose content on breadmaking potential of blends of durum and hexaploid wheat

AbstractBackground and objectivesDurum wheat is used to make leavened bread; however, durum bread has inferior loaf volume, structure, and texture compared to bread made from common wheat. One approach to overcome this is to transfer key storage protein genes present at the Glu‐D1 locus from bread wheat into durum. Durum wheat Svevo missing Glu‐B1subunits 7 + 8 and Lira biotypes with low molecular weight glutenin subunits types 1 and 2 were evaluated for their breadmaking potential with and without high molecular weight glutenin subunits 2 + 12 or 5 + 10.FindingsBread made from blends of durum and a commercial baker's flour (10%, 25%, 50% w/w) assessed over two seasons in 10 different genotypes showed that as more durum was included in the mixture, loaf volume and texture score declined. Incorporation of the 2 + 12 subunit pair in the genotypes Lira42 and Lira45 improved bread quality but not in Svevo, whereas including 5 + 10 improved bread quality of Lira42 had no effect on Lira45 but reduced quality of Svevo. Low amylose Svevo had similar loaf quality to Svevo while adding 5 + 10 had minimal impact except at 50% with a small improvement in loaf quality. Bread stored up to 7 days became firmer partly due to increased starch retrogradation, and loaves were similar to bread made from baker's flour. Low amylose Svevo kept the loaf fresher but only up to 3 days of storage. Subunit pair 5 + 10 made the loaf firmer after 7 days compared to control.ConclusionsAddition of the 2 + 12 or 5 + 10 benefited the weaker type gluten as found in Lira 42 (LMW‐1, HMW 20) but not with stronger dough in Svevo even in the absence of HMW 7 + 8. It appears that while Glu‐D1 subunits are critical for good breadmaking in hexaploid wheat, they appear to have limited value in improving loaf volume and structure in durum bread.Significance and noveltySome improvements in bread quality can be obtained by introducing genes coding for Glu‐D1subunits 2 + 12 and 5 + 10 in durum wheat depending on the genotype, especially weak dough types, and the results presented comprise the first report of such effect.

Study of a gluten-free bread made from Gagome kelp (Kjellmaniella crassifolia Miyabe).

Gluten-free bread was made from Gagome kelp, wheat starch, sugar, compressed yeast, and water. When the Gagome kelp was digested with pepsin or treated with ethyl ether, bread baked with the deproteinized or defatted Gagome kelp did not display worse properties. However, when the Gagome kelp was autoclaved at 120 ?C for 100 min, its bread making properties deteriorated markedly. A mixture of Gagome kelp and water was homogenized and centrifuged at 1,700 g. The supernatant and precipitate were subjected to bread making tests. The results indicated that the supernatant fraction had good breadmaking properties. The supernatant was further dialyzed against a large amount of water and subjected to bread making tests. The undialyzable fraction display good bread making properties. The supernatant was divided into an upper transparent layer and a lower dark and viscous layer, and bread making tests were conducted. The upper transparent layer demonstrated better bread making properties than the lower dark and viscous layer.

Safety evaluation of transgenic low-gliadin wheat in Sprague Dawley rats: An alternative to the gluten free diet with no subchronic adverse effects

Gluten-associated pathologies have increased in recent years and there is a greater demand for low or gluten-free products. Transgenic low-gliadin wheat lines showed low T-cell response, good bread-making properties, and excellent sensory assets. The aim of this study was to evaluate the safety of the whole-wheat flour from one transgenic low-gliadin line (named E82) in a 90-day feeding study. In this study males (n = 50) and females (n = 50) SD rats were used. They were fed with doses of 1.42, 2.83 and 5.67 g/kg/day of the transgenic E82 line, 5.67 g/kg/day of the WT and a blank group. We found that there were no significant differences in the development of animals. Biochemistry for liver and kidney function were similar for males and females of all groups. Other haematological and metabolic blood parameters, as well as organ weight did not show significant differences in the five groups of animals. In the histopathological study performed for the higher dose of transgenic E82 line, WT and blank group no abnormalities were observed. The whole-wheat flour of E82 line administered to rats at tested doses for 90 days did not have any adverse effects and there was no difference with the rats which ate WT wheat.

Interactions between Glu-1 and Glu-3 loci and associations of selected molecular markers with quality traits in winter wheat (Triticum aestivum L.) DH lines

The quality of wheat depends on a large complex of genes and environmental factors. The objective of this study was to identify quantitative trait loci controlling technological quality traits and their stability across environments, and to assess the impact of interaction between alleles at loci Glu-1 and Glu-3 on grain quality. DH lines were evaluated in field experiments over a period of 4 years, and genotyped using simple sequence repeat markers. Lines were analysed for grain yield (GY), thousand grain weight (TGW), protein content (PC), starch content (SC), wet gluten content (WG), Zeleny sedimentation value (ZS), alveograph parameter W (APW), hectolitre weight (HW), and grain hardness (GH). A number of QTLs for these traits were identified in all chromosome groups. The Glu-D1 locus influenced TGW, PC, SC, WG, ZS, APW, GH, while locus Glu-B1 affected only PC, ZS, and WG. Most important marker-trait associations were found on chromosomes 1D and 5D. Significant effects of interaction between Glu-1 and Glu-3 loci on technological properties were recorded, and in all types of this interaction positive effects of Glu-D1 locus on grain quality were observed, whereas effects of Glu-B1 locus depended on alleles at Glu-3 loci. Effects of Glu-A3 and Glu-D3 loci per se were not significant, while their interaction with alleles present at other loci encoding HMW and LMW were important. These results indicate that selection of wheat genotypes with predicted good bread-making properties should be based on the allelic composition both in Glu-1 and Glu-3 loci, and confirm the predominant effect of Glu-D1d allele on technological properties of wheat grains.

Wheat Flour Dough Rheological Properties Measurement: Effects of the Target Values on the Attained Results

Lubricated squeezing flow experiments on wheat flour dough have been performed in constant plate speed and constant extension rate modes. The objective of this work was to assess the effects of the target values on the attained results obtained during wheat dough rheological properties measurement. Different rheometers were used to allow these operations. In both cases, each constant target speed used increases with the increasing time before reaching its stability. These increasing effects versus time are higher with greater speeds. It was obtained 20.1–41.5% of increasing time ratio between the two modes from the lower to higher speeds and for each given speed (0.005–1.5 [mm·s−1 or s−1]). The target speed increasing in order to reach the attained value caused sample dough deformation. These strain effects of dough are more important for high initial thickness of dough. Whatever the types of dough strain needed and target speed level used, the limit force measurable in many cases was 40 N (newton). It was a constrain factor for measured values. The data processing to obtain dough rheological properties remains too long and difficult with both measurement methods. Practical Applications In search of viable ways to study dough rheological properties, the uses of empirical and fundamental methods are of appropriate possibility. Several methods are further able to be used to measure and record dough rheological properties under conditions of unsteady flow. They are used to assess flour ability and provide dough with good breadmaking performance, to mimic dough stretching and to measure its resistance to rupture. Consequently, efficient and versatile methods have opened new possibilities for studying viscoelasticity behaviors related to cereals science and processing. These benefit effects make basic new methods used in breadmaking process, a powerful tool for monitoring the consistency and structural changes in dough and final bread. Because of their major importance in breadmaking process, it is essential in this study to assess the effects of the target values on the attained results in dough rheological properties measurement methods. They can help understand their implications on the data processing of these tests for reliable research on dough rheology.

Low-Calorie Bread Baked with Charred Cellulose Granules and Wheat Flour to Eliminate Toxic Xanthene Food Dye in the Alimentary Canal

We baked low-calorie bread by mixing charred cellulose granules with wheat flour, using the charred cellulose granules to eliminate toxic xanthene food dyes contained in processed foods from the alimentary canal. The size of the charred cellulose granules played an important role in determining good breadmaking properties in respect of the bread height (mm) and specific volume (SV, cm3/g). Charred cellulose granules with a diameter above 270 μm were blended with wheat flour at 10% to obtain bread with a lower caloric content (1020 kcal/gram of bread) than the control bread (1126 kcal) made solely from wheat flour. The charred cellulose granules taken out from the bread adsorbed toxic xanthene food dyes at around pH 6.5, such that toxic food dyes taken into the alimentary canal were excreted in the feces with the non-digestible cellulose granules.

Effects of two barley β-glucan isolates on wheat flour dough and bread properties

Abstract The effects of wheat flour fortification with two different molecular weight barley β-glucan isolates (1.00 × 10 5 , BG-100 and 2.03 × 10 5 , BG-200) on the rheological properties of dough and bread characteristics, using flours from two wheat cultivars that differ in their breadmaking quality, have been examined. The farinograph water absorption of doughs and the moisture content and water activity of the breads increased with increasing β-glucan content; the β-glucan isolate with the higher molecular weight (BG-200) exerted a greater effect than did BG-100. The addition of β-glucans to the dough formula increased the development time, the stability, the resistance to deformation and the extensibility of the poor breadmaking quality doughs, as well as the specific volumes of the respective breads, exceeding even that of the good breadmaking cultivar. Furthermore, the colour of the bread crumbs got darker and their structure became coarser, whereas the bread crumb firmness decreased with increasing level of β-glucan addition. Generally, the BG-200 was more effective in increasing the specific bread volume and reducing the crumb firmness, especially when used to fortify the poor breadmaking quality flour. The results further indicate a requirement for optimisation of the fortified doughs (level and molecular size of the β-glucan) to maximise bread quality attributes (loaf volume, texture, and staling events).

Influence of water and barley β-glucan addition on wheat dough viscoelasticity

The effects of the addition of two barley β-glucan isolates (0.2–1.0% of wheat flour), differing in molecular weight, and water (53–63% in a poor breadmaking wheat flour, cv. Dion, and 58–68% in a good breadmaking wheat flour, cv. Yekora) on the viscoelastic properties of wheat flour doughs were investigated. A response surface model (CCF) was used to evaluate the effects observed on the dynamic and creep-recovery parameters of the dough. The evaluation was done separately for each combination of β-glucan isolate (BG1 of ∼10 5 Da and BG2 of ∼2 × 10 5 Da) and flour type. Besides the contents of β-glucan and water, the molecular size of the polysaccharide and the flour quality were important determinants of the dough’s viscoelastic behavior. Compared to BG1, the higher molecular weight β-glucan (BG2) brought about major changes on all the rheological responses of the fortified doughs. The addition of appropriate levels of β-glucans and water in the poor breadmaking cultivar (Dion) doughs could yield similar viscoelastic responses to those observed by a non-fortified good breadmaking quality flour dough (Yekora).

Effect of barley β-glucan molecular size and level on wheat dough rheological properties

The effect of adding low (10 5 Da) or high (2.03 × 10 5 Da) molecular weight barley β-glucans in two wheat flours of different breadmaking quality were studied. Mechanical spectra and creep–recovery analysis data within (low stress) and out (high stress) of the linear viscoelastic region were obtained. The results revealed that the rheological behavior of β-glucan-enriched doughs depend on concentration and molecular weight of the polysaccharide as well as on the flour type used. Addition of β-glucan increased the G′ values of the good breadmaking quality flour doughs, whereas decreased the G′ of the poor quality wheat cultivar. Supplementation with β-glucans increased the resistance to deformation, flowability and elasticity of the doughs under low stress. Significant correlations between frequency sweep and creep–recovery parameters of optimally developed doughs from both flours were found. The addition of β-glucan in the dough recipe of the poor breadmaking wheat flour may result in similar rheological responses to those obtained from a non-fortified good breadmaking quality wheat flour.

Detection of High Molecular Weight Glutenin Subunits in Triticale (× Triticosecale Wittm.) Cultivars by Capillary Zone Electrophoresis

An improved method for separating and characterizing high molecular weight glutenin subunits (HMW-GS) in hexaploid triticale by capillary zone electrophoresis (CZE) was developed. A low-concentrate mixture of hydrophilic polymers, poly(vinylpyrrolidone) (PVP) and hydroxypropylmethylcellulose (HPMC), in an isoelectric buffer was employed for dynamic coating of the capillary inner wall. In separation buffer PVP with lower concentrated poly(ethylene oxide) (PEO) was replaced. The CZE electropherograms of HMW-GS showed two group peaks in accordance with x- and y-type subunits with migration times of 6.8-7.8 and 8.4-11.5 min, respectively. In total, 14 HMW subunits (2 subunits encoded by Glu-A1 locus and 12 by Glu-B1) were identified. The CZE analyses revealed that each of the subunits Bx7 and By8 determined by SDS-PAGE makes up three subunits (Bx6.8, Bx7, and Bx7* and By8, By8*, and new By8**, respectively), with different migration times. It was also shown that the subunits By18 and By20 in triticale determined by SDS-PAGE have different migration times in comparison with the same subunits in bread wheat. For these new HMW-GS, the following names were assigned: By18* instead of By18 and By20* instead of By20. The presented CZE method is an efficient alternative to the SDS-PAGE procedure for early selection of useful triticale genotypes with good breadmaking quality.

Effect of Variety and Environmental Factors on Gluten Proteins: An Analytical, Spectroscopic, and Rheological Study

Four cultivars of winter wheat with contrasting qualities for breadmaking were selected to study the effects of environmental factors on grain protein composition and properties. They were grown in the field and under two controlled regimens designed to mimic typical "hot/dry" and "cold/wet" conditions experienced during grain development in the United Kingdom. The composition of the gluten proteins determined by SDS-PAGE and their size distribution determined by SE-HPLC were consistent with the presence of higher proportions of high M r polymers in the two varieties with good breadmaking performance (Spark and Soissons) with limited environmental effects on these parameters. Gluten protein fractions from three of the cultivars were analyzed by Fourier transform infrared (FTIR) spectroscopy and this, combined with creep measurements using a texture analyzer, showed that a conversion from beta-turns to beta-sheets occurred during extension, irrespective of the growth conditions. However, the breadmaking varieties Soissons and Spark showed greater differences related to environmental conditions than the variety Rialto, which has poorer processing quality.

Expression Analysis of HMW-GS 1Bx14 and 1By15 in Wheat Varieties and Transgenic Research of 1By15 Gene

High-molecular-weight glutenin subunits (HMW-GSs), one class of seed storage proteins in wheat, play an important role in determining bread-making quality of flour. More and more proves support that HMW-GS-1Bx14 and -1Bx15 subunits are strongly positively associated with good bread-making and excellent noodle-making quality. The two subunits are encoded by two genes, Glu-1Bx14 and Glu-1Bx15, which are tightly linked and located on the 1BL. Protein assay by SDS-PAGE indicated that the expression of Glu-1Bx14 gene was always much stronger than that of Glu-1By15 in the same variety. But, variation of expression level for Glu-1By15 gene existed among varieties, such as in Xiaoyan 54, Xiaoyan 6, Yanzhan 1 and Shanyou 225. We also investigated the transcription difference of Glu-1By14 and Glu-1By15 genes in Xiaoyan 54 and Shanyou 225 by semi-quantitative RT-PCR method. The Glu-1By14 always transcripts much more than the Glu-1By15. This was basically consistent with the translation difference between the two genes. Promoters of 1Bx14, 1By15, 1By8, 1Dx2 and 1Dy12 were cloned from Xiaoyan 54, Chinese Spring and Aegilops tauschii. Sequence analysis indicated that the HMW-GS genes had high homology at their promoter regions. However, significant difference existed between sequence of 1Bx14 promoter and those of other HMW-GS genes. The transient expression experiment showed that the promoter of 1By15 has lower activity than that of 1Bx14, which was consistent with their transcription level of the two genes in varieties. In addition, transient expression of the gus driven by the promoter (P2) of HMW-GS 1Dx2 gene was higher than by other HMW-GS promoters. Therefore, we constructed 1By15 gene expression vector driven by the 1Dx2 promoter, and transformed the 1By15 gene into wheat commercial variety, Jimai 20 by pollen tube method. Of 45 independent transgenic lines identified by PCR, 3 were confirmed to contain the HMW-GS 1By15 gene via Southern hybridization. The delivered 1By15 gene expressed the expected HMW-GS protein in the seeds of transgenic plants.

Formation of Dityrosine Cross-Links during Breadmaking

To establish its significance during commercial breadmaking, dityrosine formation was quantified in flours and doughs of six commercial wheat types at various stages of the Chorleywood Bread Process. Dityrosine was formed mainly during mixing and baking, at the levels of nmol/g dry weight. Good breadmaking flours tended to exhibit a higher dityrosine content in the final bread than low quality ones, but no relationship was found for dityrosine as a proportion of flour protein content, indicating that the latter was still a dominant factor in the analysis. There was no correlation between gluten yield of the six wheat types and their typical dityrosine concentrations, suggesting that dityrosine cross-links were not a determinant factor for gluten formation. Ascorbic acid was found to inhibit dityrosine formation during mixing and proving, and it has no significant effect on dityrosine in the final bread. Hydrogen peroxide promoted dityrosine formation, which suggests that a radical mechanism involving endogenous peroxidases might be responsible for dityrosine formation during breadmaking.

Molecular cytogenetic characterization and seed storage protein analysis of 1A/1D translocation lines of durum wheat

Two durum wheat [Triticum turgidum L. ssp. durum (Desf.) Husn.] lines carrying the high-molecular-weight (HMW) glutenin subunits (GS) 1 D x 5 + 1Dy10 encoded by Glu-D1d, L252 and S99B34, were characterized using fluorescent genomic in-situ hybridization (FGISH) and microsatellite markers. These two durum lines were derived from the crosses in which the common wheat (T. aestivum L.) 'Len' and durum wheat 'Langdon' (LDN) and 'Renville' were involved. FGISH patterns of the mitotic chromosomes indicated that these two durum lines have one pair of 1AS.1AL-1DL translocated chromosomes in which the terminal region of 1AL was replaced by a homoeologous segment of 1DL. The 1DL segment spans approximately 31% of the long arm of the translocated chromosome. Microsatellite marker analysis confirmed the 1AS.1AL-1DL translocation and determined the translocation breakpoint to be distal to Xgwm357 on 1AL. Seed storage proteins (GS and gliadins) were analysed in these two 1AS.1AL-1DL translocation lines and three sib lines (L092, S99B19 and S99B33) using SDS-PAGE and A-PAGE. The SDS-PAGE and A-PAGE profiles demonstrated that the two low yielding lines (L252 and S99B19) had the low-molecular-weight (LMW) -1 GS encoded by Glu-A3k and Glu-B3s and 1B-encoded gliadins from LDN, and the other three lines (L092, S99B33 and S99B34) with higher yield had LMW-2 GS and 1B-encoded gliadins from Renville, suggesting that undesirable genetic components from LDN might limit substantial improvement of yield. Thus, the translocation lines with 1 D x 5 + 1Dy10 and LMW-2, which are associated with good bread-making and pasta qualities, respectively, in a good genetic background will be useful for developing durum cultivars with dual-purpose end-use. Results from this study demonstrate that the D-genome could play an important role in the genetic improvement of durum wheat and evolution of the A- and B-genomes in tetraploid wheat.

Heat and additive induced biochemical transitions in gluten from good and poor breadmaking quality wheats

Glutens from poor breadmaking quality wheat, cv. Riband, had a higher SDS extractability than glutens from good quality cv. Hereward. Heating of gluten, especially above 70 °C, caused a reduction in the amount of SDS-extractable gluten proteins. Treatment of gluten with redox additives (ascorbic acid, potassium bromate or glutathione) affected extractability, being highest for bromate treated glutens. The SH content of gluten was lower for poor breadmaking Riband and heating resulted in greater decrease in SH content of gluten from good breadmaking Hereward. Hereward gluten had a higher SS content than Riband. The alteration of SS content on heating was not significant and may indicate the heat-induced involvement of non-covalent interactions. SDS-PAGE revealed that oxidants, especially bromate, affect polypeptide composition leading to a more heat stable/tolerant protein structure.

The physics of baking: rheological and polymer molecular structure–function relationships in breadmaking

Molecular size and structure of the gluten polymers that make up the major structural components of wheat are related to their rheological properties via modern polymer rheology concepts. Interactions between polymer chain entanglements and branching are seen to be the key mechanisms determining the rheology of HMW polymers. Recent work confirms the observation that dynamic shear plateau modulus is essentially independent of variations in MW amongst wheat varieties of varying baking performance and is not related to variations in baking performance, and that it is not the size of the soluble glutenin polymers, but the structural and rheological properties of the insoluble polymer fraction that are mainly responsible for variations in baking performance. The rheological properties of gas cell walls in bread doughs are considered to be important in relation to their stability and gas retention during proof and baking, in particular their extensional strain hardening properties. Large deformation rheological properties of gas cell walls were measured using biaxial extension for a number of doughs of varying breadmaking quality at constant strain rate and elevated temperatures in the range 25–60 °C. Strain hardening and failure strain of cell walls were both seen to decrease with temperature, with cell walls in good breadmaking doughs remaining stable and retaining their strain hardening properties to higher temperatures (60 °C), whilst the cell walls of poor breadmaking doughs became unstable at lower temperatures (45–50 °C) and had lower strain hardening. Strain hardening measured at 50 °C gave good correlations with baking volume, with the best correlations achieved between those rheological measurements and baking tests which used similar mixing conditions. As predicted by the Considere failure criterion, a strain hardening value of 1 defines a region below which gas cell walls become unstable, and discriminates well between the baking quality of a range of commercial flour blends of varying quality. This indicates that the stability of gas cell walls during baking is strongly related to their strain hardening properties, and that extensional rheological measurements can be used as predictors of baking quality.