Environmental, grain ultrastructural and biochemical properties influencing rice milling quality

A.S. M. Thushara Abayawickrama

Research output: ThesisDoctoral Thesis

134 Downloads (Pure)


Maximising head rice yield is of central importance to the global rice industry. Higher head rice yield increases the economic return to growers and millers and, more importantly, increases total edible rice production. Fissure formation in rice grains is one of the major contributing factors to grain breakage during milling. It is known that genetic variability exists for fissure formation. Moreover, adverse environmental conditions during the pre- and post-harvest periods may also influence grain fissuring. Around 10-30% of rice grains break during milling, depending on the genotype and environmental conditions. One way of reducing grain fissuring is to avoid unfavourable environmental conditions pre- and post-harvest. Another way of reducing grain fissure formation is through the development of resistant varieties. This study was conducted to ascertain the influence of: the environment, grain ultrastructure and biochemical properties on fissure formation. The results revealed that high temperature during grain filling and low grain moisture at harvest causes fissuring. This is the first demonstration of an interactive effect on fissure formation of temperature, during grain filling stage, and relative humidity, at harvesting.Also, during storage, any degree of moisture adsorption or desorption caused fissuring. It was discovered in this study that varieties with less permeable hulls, showed better resistance to fissure formation. Grain with higher protein content were less likely to fracture. Novel profiling of metabolic products in fissure resistant and susceptible varieties revealed that core metabolic products did not reveal any differences that could be used as a means to determine fissure resistance. Future work should be directed towards a search for less abundant metabolites.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Charles Sturt University
  • Harper, John, Principal Supervisor
  • Burrows, Geoffrey, Co-Supervisor
  • Reinke, Russell, Co-Supervisor
  • Fitzgerald, Melissa A., Principal Supervisor, External person
Award date25 May 2016
Place of PublicationAustralia
Publication statusPublished - 2016


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