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Wheat milling quality and its measurement Brian G Osborne BRI Research Pty Ltd, PO Box 7, North Ryde, NSW, Australia Abstract Purpose of review: The understanding of the structural and biochemical factors that control wheat (Triticum aestivum L.) milling quality has progressed rapidly over the past few years. This in turn has led to the development of mathematical models of grain morphology, endosperm structure and wheat breakage during milling. This review presents a critical interpretation of the recent peer-reviewed literature and a summary of the current state of the art in the measurement of wheat milling quality. Findings: Wheat milling quality is a complex property that involves interaction between grain morphology, separability of bran from endosperm and endosperm fracture. Detailed studies into the fracture behaviour of isolated bran and endosperm have led to a fundamental mechanical understanding of wheat milling quality. A model based on the breakage equation for roller milling now encompasses measurements of grain hardness, size, shape and moisture content in the prediction of the particle size distribution from first break milling of wheat. This enables milling quality of wheat to be better understood and measured. Limitations/implications: While the key grain properties that influence wheat milling quality have been identified and methods for their individual assessment have been devised, no single practical method can currently provide the complete information that is derived from experimental milling and analysis of the resulting flour. Perhaps the Single-Kernel Characterization System 4100 comes the closest to this goal. Directions for future research: The current breakage function does not include information on the mechanical properties of the bran layer that has been found to play a significant role in milling quality. In addition, this review does not include the role of pin genes or puroindoline proteins, since they have been studied mainly in the context of hardness rather than milling quality. However, the possible involvement of these factors in the genetic control of milling quality needs to be investigated. Keywords: Bran structure, endosperm structure, flour milling, morphology, Single-Kernel Characterization System, wheat Stewart Postharvest Review 2007, 6:11 Published online 01 December 2007 doi: 10.2212/spr.2007.6.11 |