The new study published in LWT - Food Science and Technology, reports that adding fifty per cent cassava starch to sorghum bread gave “the best overall crumb properties”, improving the overall quality of the nutrient-rich gluten free bread.
Sorghum is one of the world’s oldest known grains, and is one of a range of ancient grains that are naturally gluten-free. It has gained popularity as the market for gluten-free foods has grown, based on its greater nutritional value, compared withother gluten-free flours such as rice, corn or potato flour - however, it has physico-chemical properties that can negatively affect dough quality.
Sorghum dough lacks the consistency and elasticity associated with wheat flour dough, and when cooked, forms extended structures with embedded starch that can affect various technological properties of sorghum bread.
The dough mixture also retains gases produced from fermentation during proofing poorly, often resulting in rigid “brick-like bread with a low volume,” said the researchers.
The addition of starch to sorghum dough is thought to aid the development of a “cohesive crumb network that traps gas bubbles and prevents loss of carbon dioxide and crust collapse,” noted the authors.
Starches from different origins have different compositional and structural properties, and it is known such variance in starches can affect the properties of bread dough.
“It is … reasonable to assume that the botanical origin of starch will affect the rheological and crumb properties of sorghum batter and bread,” wrote the researchers.
The new research tested gluten-free sorghum bread made with varying levels of four different starches (cassava, maize, potato, or rice starch), investigating their effects on the properties of bread.
Crumb properties of sorghum bread were reported to improve with increasing starch content.
Increasing starch content was also seen to change the consistency from soft doughs to thin pourable batters, whilst increasing starch content decreased crumb firmness and chewiness, and increased cohesiveness, springiness and resilience in of all the breads.
The researchers noted that cassava sorghum and rice-sorghum breads had better overall crumb properties than maize-sorghum or potato sorghum breads.
The crumb properties of all breads declined upon storage, however, the formulation containing 50 per cent cassava starch was seen to retain the best overall texture.
Breads made from pourable batters were observed to possess better crumb properties than for those made from soft doughs - bread containing 50 per cent cassava was reported to have the best overall crumb properties.
Source: LWT - Food Science and Technology
Published online ahead of print, doi: 10.1016/j.lwt.2010.09.006
“Modification of gluten-free sorghum batter and bread using maize, potato, cassava or rice starch”
Authors: C. Onyango, C. Mutungi, G. Unbehend, M.G. Lindhauer