Baking tests: Effect of sucrose and water on yeast gassing power
Gélinas, P., McKinnon, C. (2018). Baking tests: Effect of sucrose and water on yeast gassing power. Cereal Chemistry, [online] 95(6), 822-828. http://dx.doi.org/10.1002/cche.10100
Plain language summary
Each year, new varieties of bread wheat are developed in Canada. Their main market is the very voluminous sandwich bread wheat market. To meet the needs of buyers, breeders need to know the qualities and defects of wheats. Some flours seem to inhibit baker’s yeast, which delays the rising of the dough and results in dense breads. The reason for this is not known.
In sweet dough, the yeast’s gas capacity increases with the flour’s water absorption capacity. This is not the case for unsweetened dough, which gives consistent results. During fermentation of the dough, the yeast is inhibited by osmotic pressure, mainly because of the presence of sugar and, to a lesser extent, the lack of water. In current tests to assess the bread-making quality of wheat, flours that are not very absorbent are penalized because sugar is added to the dough.
In conclusion, flours that are not very absorbent should be assessed in sugar-free bread recipes. This is the case for winter wheat intended for unsweetened breads in the French tradition. It will be necessary to optimize wheat assessment tests in sugar-free dough.
Background and objectives: Baking tests must be performed with formulations giving controlled gas production. The aim of this study was to investigate the effect of sucrose and water on yeast gassing power in dough. Total gas production, gas production rate, and residual fermentable sugars were determined in dough made with white flour and ten wholemeal samples. Findings: With white flour adjusted for diastatic activity, gas produced after 3 hr at 38°C was constant in dough containing up to 6% sucrose. In the latter, yeast gassing power increased according to water content contrary to non-sugared dough which gave uniform gas production. Yeast inhibition was seen with all flour samples tested. Gas production in dough also varied according to the yeast lot. Conclusions: Sucrose and lack of water inhibited yeast gassing power in dough. Depending on the water content, fermented dough with 6% sucrose produced 10%–30% less gas than non-sugared dough. Significance and novelty: Yeast was inhibited by osmotic pressure in dough containing too much sugar and, to a lesser extent, too little water, resulting in variable gas production and potential bias in bread volume. Baking tests on flour with low water absorption should be performed with non-sugared dough.