Improvement of fonio dough properties through starch modification by sourdough fermentation

Fonio is a West African millet with potential for gluten-free products. Sourdough fermentation improves fonio bread quality. To determine the cause, the effects of sourdough fermentation on the dough quality and starch characteristics of two white and two black fonio types and a white sorghum type were investigated. Sourdough fermentation substantially improved the dough consistency making it more similar to bread wheat flour, as measured by the Mixolab. Sourdough fermentation also increased pasting viscosity, an indication of effects on starch. SEM indicated that sourdough fermentation caused some slight swelling and starch leaching from the fonio starch granules. This was confirmed by an increase in damaged starch. It also caused a substantial reduction in starch gel firmness. Principal component analysis clearly separated fermented and unfermented fonio flours. Damaged starch was associated with fermented fonio, as were Mixolab parameters related to dough stability. Sourdough fermentation thus improves fonio dough and bread quality by bringing about slight changes in the starch granules, which probably increase water absorption and hence improve dough strength and gas holding.