Bread and other products made of wheat dough are the basis of nutrition for a significant part of the world's population. The international wheat science community have long been concentrated on the study of complex processes leading from wheat grain to a loaf of bread. A huge amount of data has been accumulated during this struggle for improving bread quality. This book details actual successes and problems of wheat storage-protein genetics, and discusses discrepancies, doubts and confusions of some recent experimental data. As such, it will be beneficial not only for advanced students interested in plant genetics, but also for wheat scientists and breeders.
This monograph provides a review of the knowledge that makes possible the intelligent tailoring of wheat proteins to provide for specific dough requirements. It emphasizes the combined roles of the gliadin and glutenin proteins in providing the balance that gives wheat gluten its unique rheological properties. The book gives a major update on the composition and functional properties of the gluten proteins, but it also includes introductory chapters to "set the scene" for young scientists and anyone new to this area of food science.
This book brings together recent, international contributions to the study of gluten proteins from leading experts in the field. Gluten proteins have gained greater importance due not only to their fundamental role in determining technological quality of wheat end products, but also to the apparently increased number of people showing different degrees of gluten intolerance or allergy. Along with classical subjects such as gluten genetics, quality and rheology, The Gluten Proteins covers new tools and research fields, including the use of proteomics and genomics. Furthermore, information dedicated to intolerances and allergies is included and opens the possibility to widen future research opportunities, promoting cooperation between wheat breeders, medical researchers and gluten chemists and geneticists. The Gluten Proteins provides an authoritative source of information for researchers, professionals and postgraduate students wishing to increase their knowledge of the molecular bases of gluten functionality and nutritional role, as well as touching on possible future research opportunities.
Annotation Some 120 papers continue the centuries-long research into gluten proteins, that component of wheat that confers unique visco-elastic properties to doughs and so allows the grain to be made into bread, pasta, noodles, and other human food. They cover genetics and quality correlations; biotechnology; analyzing, purifying, and characterizing gluten proteins; disulfide bonds and redox reactions; improvers and enzymic modification; quality testing; non-food uses; viscoelastisity, rheology, and mixing; gluten protein synthesis during grain development and effects of nutrition and environment; and non-gluten components. Distributed in the US by Springer-Verlag. Annotation c. Book News, Inc., Portland, OR (booknews.com).
Wheat (Triticum aestivum) is one of the world's major staple food crops, with flour produced from starchy endosperm being used for breads, cakes, noodles and various other wheat-based foods. The unique bread making properties of wheat are primarily attributed to its gluten-forming storage proteins: gliadins and glutenins. This study investigated the gluten proteins from functional and historical perspectives. The first study examined primarily the functional role of gluten proteins in the outcomes of the standard Falling Number (FN) test. The FN test is used in the grain trade to screen delivered wheat for the presence of pre-harvest sprouting by indirectly measuring [alpha]-amylase through it effects on the physical consistency of a cooked flour-water suspension. Grain protein content (GPC) has been implicated as a potential modifier of FN independent of [alpha]-amylase or sprout status. In the gluten functionality study, we proposed a protein unfolding and crosslinking model, and hypothesized that gluten proteins with higher molecular weight distributions (MWD) would heatset faster, tightly cover starch granules, restrict water entry, and slow their disintegration. In contrast to our hypothesis, our results showed that samples with lower MWD had faster heatset times than samples with higher MWD according to a controlled heating test. We also hypothesize that increased granularity of hard wheat flour reduces the surface area to volume ratio so the starch granules embedded in the particles need more time to hydrate or swell. However, our results indicated that natural variations in flour particle size from a standard grinding procedure that used a 0.8 mm screen had no impact on FN. The second study looked at potential changes in gluten proteins in a historical set of wheat varieties spanning more than 110 years of production. The wheats were in two sets: soft wheats where there has been no systematic selection for increased dough strength in breeding programs, and hard wheats where there has been a concerted effort to increase overall dough strength over the last century. The sample sets also covered the eras before and after the introduction of the semi-dwarf wheats to the USA. The reason for this investigation is related to the circumstance that wheat is the cause of celiac disease (CD) and is implcated in the disputed condition, non-celiac gluten sensitivity (NCGS). Recently, diagnoses of CD at least have increased and there are suggestions that changes in gluten proteins in the modern era are responsible. Since it is primarily gliadins that trigger CD, it was considered worth investigating whether or not there have been any changes in the composition of gliadins over the last century. Sixty-two soft and 61 hard U.S. high production wheat varieties from 1900 to the present (with one from 1800) were collected and analyzed by RP-HPLC. These varieties were investigated to begin to answer whether wheat breeding for higher dough strength, or the incorporation of dwarfing alleles after the 1960s, was associated with observable changes in gliadin composition. ANOVA showed that there was no significant difference between soft and hard wheats in the relative abundance of [alpha]/[beta]-gliadins. However, there were significant differences between hard and soft wheats in the relative abundance of [omega]- and [gamma]-gliadins. ANOVA also showed that there was no significant difference between tall and dwarf wheats in the relative abundance of any of the three gliadin fractions. The ANOVA results suggested that deliberate breeding for dough strength, as illustrated by the hard versus soft wheat contrast, had not systematically changed the relative abundance of [alpha]/[beta]-gliadins across the last 110 years, but had altered the relative abundance of the other two fractions. ANOVA results indicated no change in proportions of the three gliadin fractions after deployment of the dwarfing alleles suggesting the tall to dwarf change was independent of gluten composition. Second order polynomial regression analyses showed that the relative abundance of [alpha]/[beta]-gliadins increased until around 1960 then decreased. The changes were more noticeable in the hard wheats. The converse was observed for [gamma]-gliadins. This stepwise change questioned the association between CD increase and breeding for increased dough strength in hard wheats, since the relative abundance of [alpha]/[beta]-gliadins did not keep going up, and [alpha]-gliadin is considered the major trigger force for CD initiation. In contrast, linear correlation analyses with each of 700, three second long fractions of the RP-HPLC chromatograms suggested that most changes were related to the soft wheat population. The discrepancy between the regression analyses of the three major fractions and the 700 small fractions may be related to the use of linear correlations in the latter when some relationships were clearly non-linear. Overall, our results did not fully support speculations that there have been profound changes in gluten composition related to the dwarfing alleles or selection for increased dough strength in hard wheats.
Understanding the structural, compositional and physicochemical properties of the wheat used in bread, biscuits, pasta and other consumer products is important. This book brings together international experts to provide an overview of the progress made to date and also to give an insight into the new approaches that can be used to solve outstanding problems. It covers progress in areas including: what grain structure; structural features of the gluten proteins; structual-functionality relationships of wheat protein; lipid-binding proteins; rheology of dough systems; and the importance of non-starch polysaccharides.
Gluten consists principally of intrinsincally disordered storage proteins (glutenins and gliadins) from wheat grains. During the breadmaking process these proteins form a network that is responsible for the extraordinary viscoelasticity of wheat dough that determine the quality of bread. This book sums up the pioneering simulations of gluten proteins, aimed for recreating their unique viscoelastic properties. The computer simulations use the Dynamic Structure Based model, which enables molecular dynamics of thousands of amino acids. The corresponding time-dependent properties are studied through shear and axial deformations of the simulation box. The two types of deformation turn out to have a different impact on the proteins. Glutenins are shown to influence the mechanics of gluten much more than gliadins. The measured quantities include the response force to the deformation, the number of entanglements and cavities, the mobility of residues, the number of the inter-chain bonds, etc. The dynamic shear modulus and critical strain are also calculated. The results are consistent with the existing ideas about gluten elasticity, e.g. the slip-bond theory which assumes that the gluten proteins can be treated as an interconnected network of polymers. The simulations emphasize the role of entanglements and hydrogen bonding. Five different systems are simulated: in addition to gliadins, glutenins and gluten (a mixture of both), storage proteins from maize and rice are also considered. The last two constitute a control group, that (according to expectations) has weaker elasticity. This validates the methodology used in this approach.
From the Preface:...provides standard protocols for the extraction and analysis of wheat gluten proteins based on methods that have been tried and tested in the authors' laboratories. Extensive practical details and tips are provided, as well as suggestions for modifications and examples of applications.
