Unveiling the factors affecting milling quality of durum wheat: Influence of kernel physical properties, grain morphology and intrinsic milling behaviours

High semolina milling yield is an important intrinsic quality for durum wheat. This research investigated durum kernel physical properties, grain morphology and fracture behaviour in relation to milling yields. By analyzing fifty-two durum lines, prediction of milling quality based on kernel size and shape was found to be genotype dependent. Total milling yield (TMY) was negatively related to bran yield (R-2: 0.58-0.70, p < 0.001), whereas semolina yield (SY) was also affected by kernel hardness and mill stream release pattern. Although differences in kernel size were small between genotypes, test weight or kernel density showed potential for predicting TMY due to its negative relationship with bran yield. Analysis of mill-stream distribution of genotypes with similar kernel morphology, but varying in milling yields, showed their differences in bran yield, kernel hardness and semolina release efficiency. When grain morphology, bran yield, or kernel hardness showed weak or no relationship to milling quality, genotypes with higher SY demonstrated greater semolina release efficiency, suggesting potential differences in kernel fracture behaviour during milling. To further improve durum wheat for milling yields, it might be important to select genotypes with low bran yield and efficient semolina release, especially at early and intermediate stages of milling process.