THE EFFECTS OF PROTEIN-CONTENT AND STARCH DAMAGE ON THE PHYSICAL DOUGH PROPERTIES AND BREAD-MAKING QUALITY OF CANADIAN DURUM-WHEAT

Samples of no. 1 and no. 2 Canada Western Amber Durum wheat from two consecutive Canadian Grain Commission harvest surveys were composited according to protein content. The resulting composites were milled to achieve three levels of starch damage. When the standard ICC Alveograph test at constant water addition was performed, the curves became higher and shorter as starch damage increased, owing to the increasing flour water absorption. When Alveograph water addition was adjusted, the shape of the Alveograms was almost independent of starch damage. As protein content increased, Alveograph extensibility (length) increased. Starch damage was the predominant factor influencing Farinograph water absorption, development time and stability. Protein content exerted a moderate influence on Farinograph absorption. At low protein content, Farinograph development time and stability decreased as starch damage increased. Depending on protein content, starch damage and baking procedure, durum wheat loaf volume was 65 to 85% of that achieved for a high-quality Canadian bread wheat of comparable protein content. Remix-to-peak baking (long bulk fermentation) performance was influenced positively by protein content and was influenced negatively by starch damage. When baked by the Canadian short process (no bulk fermentation), the negative effects of starch damage on baking performance were not apparent. Bread-crumb properties of all Canadian short-process breads were much better than the corresponding remix-to-peak breads, approaching those of high-quality Canadian bread wheats. When potassium bromate was eliminated from the Canadian short process formula (which includes 37.5 ppm ascorbic acid), no negative effects on bread quality were apparent.