Nitrogen Management for Enhanced Protein: Consideration of Protein Quality for Breadmaking C. Rawluk 1, C. Grant 1, O. Lukow 2, A. Johnston 3 and R. McKenzie 4 1 AAFC Brandon Research Centre, 2 AAFC Cereal Research Centre, 3 PPIC, 4 Alberta Agriculture

Protein Content and Quality Grain protein concentration increases as N availability increases Higher protein content generally equated with higher protein quality for breadmaking Does higher protein content necessarily mean better quality?

Protein Content versus Quality Of particular concern at high N rates or late in-crop N applications How do components of breadmaking respond to N? How are components of breadmaking related to protein content?

Evaluating Protein Quality –flour and dough quality: capacity for water absorption by flour evaluation of dough during mixing and development Optimization of viscoelastic properties for dough expansion and retention –bread loaf quality: baking evaluation - size of loaf High gas production and elasticity for gas retention to produce large loaf

Protein Quality and Gluten Gluten proteins largely determine protein quality –Glutenins - elastic component of dough polymeric HMW and LMW proteins –Gliadins - viscous component of dough monomeric single-chained polypeptides Relative proportion of glutenin and gliadin and glutenin structure and distribution (HMW-GS/LMW-GS)

Effect of N Rate: Flour Protein and FAB Melfort 1998 AC Barrie r = 0.88 P <

Effect of N Rate: Flour Protein, FST and FDDT Brandon 1999 r = r = 0.84 P < Katepwa

Effect of N Rate - Bread Baking

Protein Content and Quality: Cultivar Difference

Effect of N Source and Timing: Flour Protein and FAB

Effect of N Source and Timing: Flour Protein and FDDT

Effect of N Source and Timing: Flour Protein and FST

Effect of N Source and Timing: Flour Protein and FTBD

Effect of N Source or Timing

N Rate, Timing and Source What benefits protein content tends to also benefit protein quality protein content, flour water absorption, dough strength and stability, and loaf volume increased with increasing N rate combination of timing and source more important than source alone possible exception at very high N rates where may have other limiting factors eg. N:S ratio in grain