Influence of genotype and protein content on the baking quality of hearth bread

The relationships between protein content and quality and the loaf characteristics of hearth breads made from the respective flours were investigated for 20 wheat genotypes, comprising both commercially grown cultivars and advanced breeding lines, grown in 1997 and 1998. In both years the average protein content was increased by increasing the level of nitrogenous fertiliser application, this effect being more pronounced in 1997 than in 1998. Grain samples were milled and evaluated for endosperm hardness, protein content, SDS sedimentation volume, mixing properties and baking quality determined by a hearth bread baking test using optimal mixing and fixed proving time. When producing hearth bread, both the form (height/width) ratio and loaf volume are critical external characteristics. Genotype differences, mainly due to differences in protein quality, were more important for both form ratio and loaf volume than differences in protein content. The dough development time of the Farinograph, operated at high speed (126 rev min^-1), was the best indicator of heart bread baking quality, giving high positive correlations to both the volume (r = 0.89) and form ratio of the loaf (r = 0.90). Climatic differences between the two years, in particular temperature during ripening, also affected the quality parameters studied.