Ferenc Békés

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

ABSTRACT 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, ...

The characterisation and mapping of a family of LMW-gliadin genes: effects on dough properties and bread volume

Abstract.Analysis of a cDNA library from wheat cv Wyuna endosperm, indicated a significant size and sequence variation among seed-endosperm protein genes. In this study, a family of low-molecular-weight seed protein genes are analysed that are related to the gliadins and the low-molecular-weight glutenin subunits. Sequence analysis and comparison of these proteins showed that they are closely related to a 17-kDa protein from barley, ε hordein, which plays a role in beer foam stability in the brewing industry. Mapping of these genes in wheat shows that they are located on group 7 and 4 chromosomes, as opposed to a group 1 and 6 location for the glutenins and gliadins. It is possible that this family of proteins forms a new class of seed-endosperm proteins important in defining the quality characteristics of wheat flour. Therefore, a representative gene from this family was expressed in Escherichia coli and the purified protein was supplemented into a base wheat flour. Rheological analysis showed that the protein effected dough strength and resistance break down during mixing of the dough, and provided a 20% increase in loaf height after baking.

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.

Effect of storage of adzuki bean (Vigna angularis) on starch and protein properties

Differential scanning calorimetry was used to evaluate the effect of storage at 10degreesC, 20degreesC and 30degreesC, and 40% and 65% relative humidity (RH) on adzuki bean starch gelatinisation and protein denaturation temperatures. Storage for 6 months at an elevated storage temperature (30degreesC) caused increases in the starch gelatinisation onset temperature (T-o) and gelatinisation peak temperature (T-p) for both Bloodwood and Erimo varieties. Storage at 40% RH resulted in higher T-o and T-p values than storage at 65% RH. The T-o of starch from Bloodwood and Erimo beans stored for up to 1.5 months at 10degreesC and 65% were similar to those of fresh beans. The changes in the salt-soluble protein component were less clear cut than those of the starch. Nonetheless, protein extracted from beans stored at 40% RH exhibited significantly lower T-o and T-p values compared with those stored at 65% RH. This indicates some destabilisation of the protein at the higher RH. These results suggest that detrimental changes occur in starch and, to a lesser extent protein, of adzuki beans stored under unfavourable conditions. On the basis of these results, the best storage conditions to maintain the characteristics of fresh beans are low temperatures (e.g. 10degreesC) and high RH (e.g. 65%)

Measurement of the protein composition of single wheat kernels using near infrared spectroscopy

Near infrared (NIR) spectroscopy of single seeds of cereal grains would allow their quality testing to be performed at earlier stages in breeding programmes than at present and for seeds of individual lines to be sorted into fractions of contrasting quality. Previous single-kernel NIR research involving cereals has been directed at traits such as protein content and seed colour for which NIR analysis is well-established. However, the development of methods for more complex traits such as wheat protein composition, which relate directly to end product performance, would be of particular use in plant breeding applications. NIR spectra of 200 single wheat seeds representing varieties with different protein composition profiles were measured using both a dispersive and a diode array instrument together with specially-designed sample accessories. The same seeds were then subjected to biochemical analysis using HPLC methods to determine their protein compositions. Predictive models were developed which showed that NIR measurements of single seeds could be used to determine the uniformity of a wheat sample, or to sort seeds, with respect to the concentrations of protein components.

Preparative Method for In Vitro Production of Functional Polymers from Glutenin Subunits of Wheat

ABSTRACT An in vitro method for preparative-scale production of artificial glutenin polymers utilizes a controlled environment for the oxidation of glutenin subunits (GS) isolated from wheat flour to achieve high polymerization efficiency. The functionality of in vitro polymers was tested in a 2-g model dough system and was related to the treatment of the proteins before, during, and after in vitro polymerization. When added as the only polymeric component in a reconstituted model dough (built up from gliadin, water solubles, and starch fractions), in vitro polymers could mimic the behavior of native glutenin, demonstrating properties of dough development and breakdown. Manipulating the high molecular weight (HMW)-GS to a low molecular weight (LMW)-GS ratio altered the molecular weight distribution of in vitro polymers. In functional studies using the 2-g mixograph, simple doughs built up from homopolymers of HMW-GS were stronger than those using homopolymers of LMW-GS. These differences may be accounted ...

New aspects in quality related wheat research: II. New methodologies for better quality wheat

The aim of this two-part review is to highlight some of the numerous newer aspects of quality related wheat research and its achievements in the last two decades. The first part described the directions of more and more multi-interdisciplinary wheat quality oriented research with an enlarging gap between breeding — and industry oriented quality research. These general comments were followed by the session describing our understanding the role of components of wheat flour determining bread-making quality. This second part of the review overlooks the new directions of quality related basic and applied research in pre-breeding and breeding as well as in the wheat industry, including genetic, molecular biological, biochemical chemical, instrumental and model-making/predictive methodologies. A brief coverage of the directions and achievement in the more and more important two non-traditional quality areas, the nutrition- and health-related quality attributes are followed by a short conclusion and speculation on future direction.

Comparative Study of the Effect of Incorporated Individual Wheat Storage Proteins on Mixing Properties of Rice and Wheat Doughs

The aim of this work was to compare the effects of incorporated wheat storage proteins on the functional properties of rice and wheat flours. The advantage of rice as a base flour compared to wheat is that it does not contain any wheat flour components and, therefore, has no interactive effect between wheat glutenin proteins. The incorporation of individual HMW glutenin subunit proteins (Bx6, Bx7, and By8) in different ratios had significant positive effects on the mixing requirements of both rice and wheat doughs. Reconstitution experiments using two x+y type HMW-GS pairs together with a bacterially expressed LMW-GS have been also carried out in this study. The largest effects of polymer formation and mixing properties of rice flour dough were observed when Bx and By subunits were used in a 1:1 ratio and HMW and LMW glutenin subunits in a 1:3 ratio. However, using the same subunit ratios in wheat as the base flour, these synergistic effects were not observed.

Wheat beta-expansin (EXPB11) genes: Identification of the expressed gene on chromosome 3BS carrying a pollen allergen domain

BackgroundExpansins form a large multi-gene family found in wheat and other cereal genomes that are involved in the expansion of cell walls as a tissue grows. The expansin family can be divided up into two main groups, namely, alpha-expansin (EXPA) and beta-expansin proteins (EXPB), with the EXPB group being of particular interest as group 1-pollen allergens.ResultsIn this study, three beta-expansin genes were identified and characterized from a newly sequenced region of the Triticum aestivum cv. Chinese Spring chromosome 3B physical map at the Sr2 locus (FPC contig ctg11). The analysis of a 357 kb sub-sequence of FPC contig ctg11 identified one beta-expansin genes to be TaEXPB11, originally identified as a cDNA from the wheat cv Wyuna. Through the analysis of intron sequences of the three wheat cv. Chinese Spring genes, we propose that two of these beta-expansin genes are duplications of the TaEXPB11 gene. Comparative sequence analysis with two other wheat cultivars (cv. Westonia and cv. Hope) and a Triticum aestivum var. spelta line validated the identification of the Chinese Spring variant of TaEXPB11. The expression in maternal and grain tissues was confirmed by examining EST databases and carrying out RT-PCR experiments. Detailed examination of the position of TaEXPB11 relative to the locus encoding Sr2 disease resistance ruled out the possibility of this gene directly contributing to the resistance phenotype.ConclusionsThrough 3-D structural protein comparisons with Zea mays EXPB1, we proposed that variations within the coding sequence of TaEXPB11 in wheats may produce a functional change within features such as domain 1 related to possible involvement in cell wall structure and domain 2 defining the pollen allergen domain and binding to IgE protein. The variation established in this gene suggests it is a clearly identifiable member of a gene family and reflects the dynamic features of the wheat genome as it adapted to a range of different environments and uses.Accession Numbers: ctg11 =FN564426Survey sequences of TaEXPB11ws and TsEXPB11 are provided request.

Applications and limitations of immunochemical analysis of biopolymer quality in cereals

The mixing and baking properties of wheaten doughs are determined largely by the content, composition and interactions of the major groups of flour proteins, the disulphide‐bonded glutenin subunits and monomeric gliadins. Prediction of dough and bread quality is currently based on medium‐scale rheological and baking tests, but the slow throughput of such tests limits their use both by millers and baking companies and in early‐generation screening by plant breeders. Thus identification and quantification of specific flour proteins by immunoassay has the potential advantages of speed, simplicity and applicability to small samples in breeding. Technical problems can arise from the low solubilities of these proteins and their high degrees of sequence homology (which often give rise to extensive antibody cross‐reaction). These problems can be minimized by modifications to methods and combining monoclonal antibodies with selected extraction conditions to enhance the functional specificity of the assay. Limitati...