Effects of water deficit and high N fertilization on wheat storage protein synthesis, gluten secondary structure, and breadmaking quality

The content and composition of wheat storage proteins are the major determinants of dough rheological properties and breadmaking quality and are influenced by cultivation conditions. This study aimed to investigate the effects of water deficit and high N-fertilizer application on wheat storage protein synthesis, gluten secondary structure, and breadmaking quality. Reverse-phase ultrahigh-performance liquid chromatography analysis showed that storage protein and gluten macropolymer accumulation was promoted under both independent applications and a combination of water-deficit and high N-fertilizer treatments. Fourier-transform infrared spectroscopy showed that water deficit and high N-fertilizer treatments generally improved protein secondary structure formation and lipid accumulation, and reduced flour moisture. In particular, high N-fertilizer application increased β-sheet content by 10.4% and the combination of water-deficit and high N-fertilizer treatments increased random coil content by 7.6%. These changes in gluten content and secondary structure led to improved dough rheological properties and breadmaking quality, including superior loaf internal structure, volume, and score. Our results demonstrate that moderately high N-fertilizer application under drought conditions can improve gluten accumulation, gluten secondary structure formation, and baking quality.