Gliadin and glutenin : the unique balance of wheat quality

464 Pages·2006·4.843 MB·English

by  Colin Wrigley, Ferenc Bekes, Walter Bushuk, Colin Wrigley, Ferenc Bekes, Walter Bushuk

Cover: Stretching photos provided by S. Uthayakumaran
and C.W. Wrigley.

Library of Congress Catalog Card Number: 2006923537
ISBN-13: 978-1-891127-51-9
ISBN-10: 1-891127-51-9

©2006 by AACC International
This book was formatted from computer files
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Contributors
Robert P. Anderson, Autoimmunity and Transplantation Division, Walter
and Eliza Hall Institute, Parkville, Australia 3050
Ian L. Batey, Food Science Australia and Wheat CRC, North Ryde
(Sydney), NSW 1670, Australia
Ferenc Békés, CSIRO Plant Industry, Canberra, ACT 2600, Australia
Gerard P. Branlard, UMR INRA-UBP, Amélioration et Santé des Plantes,
234 Avenue du Brezet, 63100 Clermont Ferrand, France
Walter Bushuk, Food Science, University of Manitoba, Winnipeg, MB
R3T 2N2, Canada
Colin R. Cavanagh, CSIRO Plant Industry, Canberra, ACT 2600, Australia
Geoffrey B. Cornish, Grain Quality Research Laboratory, South Australian
Research and Development Institute, Urrbrae, South Australia,
Australia
James E. Dexter, Canadian Grain Commission, Grain Research
Laboratory, 1404-303 Main St, Winnipeg MB, R3C 3G8 Canada.
Howard A. Eagles, The University of Adelaide, Glen Osmond, South
Australia, Australia
Kevin R. Gale, Environment Protection Branch, Policy Coordination &
Environment Protection Division, Department of the Environment &
Heritage, GPO Box 787, Canberra, ACT 2601, Australia
M. Cristina Gianibelli, CSIRO Plant Industry, GPO Box 1600, Canberra
ACT 2601, Australia
Robert A. Graybosch, USDA-ARS, University of Nebraska, Lincoln, NE
68583, USA
Nigel G. Halford, Rothamsted Research, Harpenden, Hertfordshire AL5
2JQ, UK
Crispin A. Howitt, CSIRO Plant Industry, Canberra, ACT, Australia
Berne L. Jones, RR1, Box 6, Kooskia, Idaho 83539, USA
Angela Juhász, Agricultural Research Institute of the Hungarian Academy
of Sciences, 2 Brunszvik, Martonvásár, H-2462, Hungary
Domenico Lafiandra, Dipartimento di Agrobiologia ed Agrochimica,
Università degli Studi della Tuscia, Via San Camillo de Lellis, Viterbo
01100, Italy
George L. Lookhart, Department of Grain Science and Industry, Kansas
State University, Manhattan, KS, 66506 USA
Finlay MacRitchie, Kansas State University, Manhattan, Kansas, USA
Eugene V. Metakovsky, Calle Montera, 42, Piso 6, Madrid 28013 Spain
Craig F. Morris, USDA ARS Western Wheat Quality Lab., Pullman, WA
99164-6394 USA
iii
iv / Contributors
Manoj D. Oak, Genetics Department, Agharkar Research Institute,
Agarkar Road, Pune 411004, India.
Peter I. Payne, Bury St. Edmunds, Suffolk, IP29 4BY, United Kingdom
Peter R. Shewry, Rothamsted Research, Harpenden, Hertfordshire AL5
2JQ, UK
Laszlo Tamás, Eotvos Lorand University of Sciences, 1/C Pazmany Peter
stny, Budapest, Hungary
Surjani Uthayakumaran, Food Science Australia and Wheat CRC, North
Ryde (Sydney), NSW 1670, Australia
Herbert Wieser, Deutsche Forschungsanstalt für Lebensmittelchemie,
Garching, Germany
Colin W. Wrigley, Food Science Australia and Wheat CRC, North Ryde
(Sydney), NSW 1670, Australia
Preface
Recent decades have seen an unprecedented increase in our knowledge
about the chemistry, genetics and functionality of wheat gluten, and about
the balance between the component gliadin and glutenin proteins. These
advances now permit the intelligent tailoring of varieties to appropriate
dough-quality requirements. It is thus important to provide a review of this
information and of its potential application for the benefit of the wheat
industry. That is the purpose of this book.
The generation change
However, many researchers in the generation that has been responsible
for these advances are on the verge of retirement, so it has been critical to
have them contribute their knowledge before their expertise is lost to cereal
chemistry. This book offered AACC International the unique opportunity of
capturing the combined expertise and experience of these “father” figures of
cereal chemistry, whilst injecting the enthusiasm and new ideas of younger
co-authors.
A specific example of the potential for the loss of accumulated
knowledge is the case of Dr Eugene Metakovsky, a Russian scientist who
has made enormous contributions to our understanding of gliadin genetics.
A few years ago, Dr Metakovsky realized that he would be unable to
continue his research career, following the dramatic changes in Russian
funding of research. Accordingly, he summarized his many years of
research on gliadin proteins in 75 quarto pages of single-spaced typing,
copies of which he sent to Walter Bushuk (in Canada) and to Colin Wrigley
(in Australia), with the request that they should see to having it published!
Various avenues were pursued in attempts to fulfill this request.
Eventually, this stimulus led to the concept of this book. Much of Eugene
Metakovsky’s 75-page legacy is incorporated into Chapters 2, 3 and 4 of
this book, as well as in the exhaustive catalog of gliadin composition that is
now available on the web site of AACC International (see the Grain Bin
section at http://www.aaccnet.org). However, the editors deemed it essential
that this book should go beyond an up-date on the gliadin proteins, to
emphasize the combined roles of the gliadin and glutenin proteins in
providing the balance that gives wheat gluten its unique rheological
properties.
A major update on gluten proteins
This book reviews current knowledge about the composition and
functional properties of the gluten proteins, commencing with an
introductory chapter that is designed to set the scene for new-comers to the
v
vi / Preface
field, as well as providing a basis on which subsequent chapters might build
with more specific information.
Two triplets of chapters follow, first on the gliadin proteins (Chapters 2
to 4) and then describing the glutenin proteins (Chapters 5 to 7). These
review the latest details of the chemistry, genetics and function of these
proteins. An important aspect covered for glutenin is their structure and
function as polymers of polypeptides (Chapter 7).
Applying the new knowledge
Chapters 8 to 13 describe several ways in which our increased
knowledge of gluten proteins can be used in practical applications, such as
the prediction of dough properties (Chapters 8 and 9), for identifying
varieties (Chapter 10), and as diagnostic markers of various aspects of grain
quality (Chapter 11). A chapter that could not have been written a decade or
so ago follows (Chapter 12), telling of the potential for genetic
manipulation to provide new insights into gluten-protein function and its
manipulation. Finally, in this section, Chapter 13 explains how discoveries
in gluten research have assisted in the diagnosis and treatment of medical
conditions related to gluten proteins.
The “other” proteins
The full story of dough quality cannot be fully told in terms of gliadin
and glutenin, so Chapter 14 describes the various roles of several classes of
protein that are not normally considered to be in the category of a “gluten
protein”. The contents close with some speculation about future possibilities
for further elucidating and manipulating the gliadin-glutenin balance,
thereby exercising “intelligent” control over wheat quality and the
processing of wheat-based foods.
The appendix provides information about the sources of data on the
composition and genetic constitution of a wide range of wheat genotypes.
Overall, this information proved to be so extensive that the only feasible
possibility was to provide the list on the web site of AACC International
(http://www.aaccnet.org; See “Grain Bin”).
The review process: Acknowledgements
All chapters went through the traditional process of peer review,
criticism and consequent revision, plus editing of expression and format.
The editors greatly appreciate the contributions of many scientists who
acted as peer reviewers of the chapters. These include Ann Blechl, Sylvie
Cloutier, Frances Dupont, Brigitte Dupuis, Neil Howes, Khalil Khan, Finlay
MacRitchie, Hamid Naeem, Manoj Oak, Harry Sapirstein, Mike Sissons,
Surjani Uthayakumaran and Herbert Wieser. We also thank the authors for
the timely submission of their manuscripts. This book has only been
possible with the editorial and publishing expertise provided by the staff of
AACC International.
Preface / vii

Our audience
The topic for this book is the “core business” of the AACC. The
intended audience is all those who have an interest in wheat quality. Dough
properties, the main focus of the book, are critical to all parts of the wheat
industry, because it is the unique rheological properties of wheat that make
it the grain of greatest value and widest use in the world. The readership
thus includes all users of wheat from breeders to food scientists in industry,
plus staff, researchers and students in universities and research institutes
world-wide.
We three editors feel privileged to have had the experience of living
and working through the past 40 to 50 years—the period of history during
which the greatest strides ever have been made in understanding the
chemistry of wheat quality. We trust that this book will provide a long-term
reference book for cereal chemists by providing current knowledge in the
context of the historical background to these research advances.
Colin Wrigley
Ferenc Békés
Walter Bushuk
Contents
Preface...........................................................................................................v

Section I. Introduction
Chapter 1. Gluten: A Balance of Gliadin and Glutenin.................................3
C.W. Wrigley, F. Békés, and W. Bushuk

Section II. Gliadin
Chapter 2. Gliadins of Common Wheat: Polymorphism and Genetics.......35
E.V. Metakovsky, G.P. Branlard, and R.A. Graybosch

Chapter 3. Gliadin Alleles in Wheat: Identification and Applications........85
E.V. Metakovsky and R.A. Graybosch

Chapter 4. Some Gli Alleles Related to Common Wheat
Dough Quality...........................................................................................115
G.P. Branlard and E.V. Metakovsky

Section III. Glutenin.............................................................................141
Chapter 5. The High-Molecular-Weight Subunits of Glutenin.................143
P.R. Shewry, N.G. Halford, and D. Lafiandra

Chapter 6. Low-Molecular-Weight Glutenin Subunits: Insights into This
Abundant Subunit Group Present in Glutenin Polymers...........................171
A. Juhász and M.C. Gianibelli
Chapter 7. The Polymeric Glutenins.........................................................213
H. Wieser, W. Bushuk, and F. MacRitchie

Section IV. Practical Uses of Gluten-Composition
Knowledge
Chapter 8. Prediction of Dough Properties for Bread Wheats...................243
G.B. Cornish, F. Békés, H.A. Eagles, and P.I. Payne
Chapter 9. Chemistry, Genetics and Prediction of Dough Strength
and End-use Quality in Durum Wheat......................................................281
M.D. Oak and J.E. Dexter
Chapter 10. Genotype Identification.........................................................307
S. Uthayakumaran, C.W. Wrigley, I.L. Batey, W. Bushuk,
and G.L. Lookhart
ix
x / Contents

Chapter 11. Diagnostic Markers for Quality.............................................333
C.A. Howitt, K.R. Gale, and A. Juhász

Chapter 12. Genetic Manipulation of Gluten Structure and Function.......363
P.R. Shewry, D. Lafiandra, L. Tamás, and F. Békés

Chapter 13. Medical Applications of Gluten-Composition Knowledge....387
R.P. Anderson and H. Wieser

Section V. A Wider View of Wheat Quality
Chapter 14. Proteins that Complement the Roles
of Gliadin and Glutenin.............................................................................413
B.L. Jones, C.F. Morris, F. Békés, and C.W. Wrigley

Chapter 15. Manipulation of the Gliadin-Glutenin Balance......................447
C.W. Wrigley, F. Békés, C. R. Cavanagh, and W. Bushuk

Appendix: Gliadin and Glutenin-Subunit Composition Data
Provided on the AACC International Website..........................................453

Index.........................................................................................................461
SECTION I
Introduction
The terms “gliadin” and “glutenin” were adopted in the
1890s by T.B. Osborne, as the names for the apparently
“single” proteins of wheat gluten in the classes of prolamin
and glutelin, respectively. Researchers of that era had
an appreciation, possibly more intuitive than experiential,
that these two proteins were complementary, and that an
understanding of the balance between them would lead to the
elucidation of the chemical basis of dough quality.
More than a century later, we have an enormous reservoir
of research results, telling us about the chemistry of the many
protein components of gliadins and glutenin. The concept of
a balance between gliadin and glutenin is still appropriate,
and is the theme of this book and the illustration below. The
mixing curves (top row of illustration), dough extension traces
(middle row), and bake-test loaves show that flour with too
much gliadin (left column) or too much glutenin (right column)
has lower dough and baking quality than flour with optimal
balance of gliadin and glutenin (center column).
This introductory chapter sets the scene as an overview,
a basis for reading the subsequent specific chapters.
Figure courtesy of H.D. Sapirstein, unpublished.
Chapter 1
Gluten: A Balance of Gliadin and Glutenin
C.W. Wrigley,1 F. Békés,2 and W. Bushuk3
1Food Science Australia and Wheat CRC, North Ryde (Sydney), NSW
1670, Australia
2CSIRO Plant Industry, Canberra, ACT 2600, Australia
3Food Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada

INTRODUCTION
The simplicity with which gluten can be purified from flour by water-
washing made it one of the first proteins to be isolated in reasonably pure
form. This achievement was first reported by Beccari of Bologna, in 1728
(see Bailey 1941), but it was still many years before the chemical
constitution of proteins was elucidated, and before the term “protein” was
coined. This occurred in 1838 when Berzelius wrote to Mulder; see
Hartley (1951). The term “gliadine” predated even this, being suggested
by G. Taddei in 1819, based on the demonstration by Einhof, in 1805, that
gluten could be separated into two fractions, based on the extractability of
gliadin in aqueous ethanol. The insoluble residue was named “zymom” by
Taddei, “plant albumin” by Berzelius in 1826; also “glutin” by de
Saussure in 1833 and by Dumas and Cahours in 1843 (Osborne and
Vorhees 1893; Wrigley 1993). By the end of the nineteenth century, the
terms “gliadin” and “glutenin” were established to describe the two halves
of gluten that were extractable and residual, respectively, using 70%
aqueous ethanol (Osborne and Vorhees 1893). Significantly, the chemical
distinction between these two fractions was demonstrated on the basis of
their respective contents of proline and glutamic acid, and the degree of
amidation (Osborne and Clapp 1906). Nevertheless, there was the
erroneous assumption that each of these components was a pure
homogeneous protein.
Researchers in America, Australia, England and France pursued the
concept that variations in gluten quality (and thus in dough properties)
could be explained by varying the balance between these two major
components of gluten. Pursuit of this hypothesis led to the appearance of
several conflicting reports of the ratio between gliadin and glutenin in the
literature of the late nineteenth century, with values for this ratio ranging
from 0.59 to 4.0 (see Tracey 1967). Reasons for these wild variations
appear to relate mainly to differences in extraction procedures, but also to
difficulties in obtaining reproducible results with extraction as the method
of fractionation.
3