Milling and baking quality of hexaploid spring wheat starch synthase IIa (ssIIa) mutants with elevated amylose content

Abstract

AbstractBackground and objectivesNovel 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.FindingsTriple 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.ConclusionsHigh 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 noveltyOur results demonstrate that flour with increased amylose levels can be used to create bread with increased protein and dietary fiber.