Both in Bilux flour and Terroir whole meal doughs, wheat grain fructans were the primary source of fermentable sugars during the early stages of fermentation. Only when glucose and fructose, derived from fructan, sucrose and raffinose hydrolysis, were largely depleted, yeast cells started consuming maltose, resulting in a temporary lag phase in CO2 production. During a 2 h fermentation process, about half of the sugars consumed in Bilux dough were derived from damaged starch through the action of amylases, while the other half are sugars were released from fructan, sucrose and raffinose by yeast invertase. In Terroir whole meal dough, the role of invertase activity was even bigger, with 70% of the sugars consumed being released by invertase activity, which emphasizes the importance of invertase activity for sugar release in dough. Since degradation of fructan and also sucrose, leading to the sugars that are primarily consumed during the first hour of fermentation, is completely independent of the amylase activity of the flour, the amylolytic activity of the flour does not determine the fermentation rate during the first one or two hours of fermentation. The amylolytic activity of the flour, which is determined by the FN and the damaged starch content, mostly influences fermentation period after the lag phase has occurred. Indeed, higher maltose levels prolong fermentation, which is of importance for dough leavening during proofing and baking when longer productive fermentation times are required.