The quality of wheat-based food. products, especially bread quality, is significantly affected by the characteristics of the wheat flour, both in term of processing quality and nutritional value. White flour, by far the most used flour in breadmaking, derives from grinding of the grain starchy endosperm. Several studies have demonstrated that the endosperm tissue shows significant inhomogeneity in its chemical composition, with both quantitative and qualitative patterns of tissue distribution observed for all its main storage components. This project has focused on a detailed study of the spatial distributions of proteins and starch within the wheat endosperm, how they are influenced by genetic and environmental factors and how they affect the processing properties of the flour. Multiple technologies, including protein/starch chemistry, immunocytochemistry and microscopy, have been used to achieve the research aims. The results show a clear deceasing gradient in total protein in the endosperm from the subaleurone toward the centre of the grain. Strong spatial gradients were also observed in the composition of gluten proteins. These patterns were best visualised in vivo by Immunofluorescence microscopy. The SE-HPLC profiles, which can be used to predict processing quality, also showed gradients across the grain. The pattern of distribution of starch showed an opposite trend to that of proteins, being higher in the central endosperm cells than in subaleurone cells. 1 The amylose/amylopectin ratio also varied spatially in grain of some of the cultivars. Strong genotype effects were found for all parameters that were measured. Nitrogen fertilisation was found to have a strong impact on the amount of protein (both quantity and quality) and their distributions. Moreover, it also influenced, albeit to a much smaller extent, the amount of starch. The detailed information on protein and starch distribution within endosperm and effects of genotype and nitrogen fertiliser from this study provided knowledge that would lead to greater understanding of protein and starch synthesis as well as nutrition transport within grain. It is also potentially beneficial for improving milling technology and selecting breeding candidates for different purposes.
He, Jibin
Department of Sport and Health SciencesFaculty of Health and Life Sciences
Year: 2012
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