Background and objectives Novel alleles of starch synthase II (ssIIa) homeologs were
created in a soft white spring wheat using chemical mutagenesis and then combined
to create four unique ssIIa triple mutant haplotypes. Previous research found the
resultant triple ssIIa mutants were hard in texture and had increased seed amylose
and protein content that was strongly correlated with decreases in individual seed
weight and seed starch content. The objective of this research was to examine how
these changes in amylose content affect milling and bread baking characteristics.
Findings Triple ssIIa mutant haplotypes yielded significantly less flour that had
a higher protein and ash content, decreased brightness, and increased yellowness and
redness compared to controls. Solvent retention capacity tests on flour from ssIIa
mutant lines had significant increases in water, sucrose, and sodium bicarbonate absorption
but similar lactic acid absorption and poor gluten performance indexes compared to
controls. Flour dough made from ssIIa mutants had increased water absorption with
increased mixing tolerance and produced bread with significantly reduced loaf volume,
crumb grain score, and crumb brightness with increased crumb yellowness and redness.
Attempts to restore loaf volume using up to 6% vital wheat gluten were unsuccessful.
Conclusions High amylose ssIIa triple mutants have significant decreases in flour
yields as a result of their diminished starch content and seed size. The unique composition
of flour from ssIIa triple mutants does not readily lend itself to producing a functional
dough for bread making and resultant bread has significant decreases in loaf volume.
Significance and novelty Our results demonstrate that flour with increased amylose
levels can be used to create bread with increased protein and dietary fiber.
