G.B. Cornish, Grain Quality Research Laboratory, South Australian Research and Development Institute, Urrbrae, South Australia, Australia; F. Békés, CSIRO Plant Industry, Canberra, ACT, Australia; H.A. Eagles, The University of Adelaide, Glen Osmond, South Australia, Australia; P.I. Payne, Bury St. Edmunds, Suffolk, IP29 4BY, United Kingdom
Gliadin and Glutenin: The Unique Balance of Wheat Quality
Pages 243-280
DOI: https://doi.org/10.1094/9781891127519.012
ISBN: 978-1-891127-51-9
Abstract
The way a dough behaves when flour and water are initially mixed, and during further processing, are vitally important in determining the food quality of the end product. Rheology is the study of the flow of a material, which is deformed over time when a strain is applied. Dough is a viscoelastic polymer and hence its properties depend on how quickly the test is performed. Dough rheology has a major impact on the processing and quality of the end products such as bread, noodles and biscuits (cookies). Hence accurately defining dough rheology to predict end-product quality has been and continues to be a major challenge for the cereal chemist.
The rheological behaviour of a particular dough depends on the interaction of the genotype with the environment (G X E). The protein polypeptides, in particular the high-molecular-weight glutenin subunits (HMW-GS) and the low-molecular-weight glutenin subunits (LMW-GS), make a major contribution to the gluten macropolymer. The HMW-GS and LMW-GS are coded by the Glu-1 and Glu-3 genes, respectively. A wheat breeder-cereal chemist team can select for these six glutenin alleles and hence affect the genotype of a wheat variety. Environmental conditions, such as soil type, rainfall and temperature, can influence the proportion and amount of protein deposition in the developing wheat kernel. Hence, the environment modifies the genetic potential of a wheat variety. The grain received after harvest will have both G and E components. The G X E interactions affect the way the grain behaves during processing and hence the end-product quality of food. Cereal science has come a long way from the days when the total protein content was used as the main measure of processing quality. Not only is the total amount of protein important but also the percentage of different types of protein, such as the insoluble or unextractable polymeric protein (UPP), and the amount and type of the individual glutenin subunits. These affect the dough properties and hence the marketability of a wheat sample.
