Hello @keto-jen, I apologize for my delay in contributing.
yYeast requires simple sugars, or carbs, to ferment. The fiber in inulin is too complex for the enzymes to digest, just like for us humans. The oligiosaccharides are also more complex and provide only very little for the yeast to digest. Additional information will help distill responses to more effective application for you.
To start with I see this as a 2 part answer. Assuming you are adding inulin for fiber source, I would look to other sources, as inulin is not recognized as a fiber source for nutritional claims, and it contributes to gastro intestinal distress for most people. A soluble fiber source like beta glucan in the Soulanges heat treated oat flour, or other soluble fibers from maltodextrins you can obtain from MGP and other suppliers.
For the fermentation I suggest looking to IREKS for a suitable malt powder to add. You use only small amounts, 0.5-4% of the bulk “flour” weight, and get big results from the enzyme activity to aid fermentation, and flavor, as well as color if desired with some. IREKS have a Spelt Malt that is very nice.
I hope this is helpful, and please let us all know if you have any further questions, and what does or does not work for you.
