Yeast as a thickener?
So I made two batches of cake donuts the other day which contained significant amounts of starch. They were identical in every aspect, except I used 1/2tsp yeast for one and 1/2tsp baking powder for the other. For whatever reason, the baking powder batch was significantly thinner.
My question is, why would such a tiny ingredient make such a world of difference in viscosity? I don't think the yeast provided much leavening (since it was a batter), but it made the dough much thicker. Is there anything I can use in place of yeast to make batter thicker? I've tried xanthan gum, potato starch, and tofu, but they drastically change the texture of the finished product. Is there a difference between active dry and instant yeast in terms of thickening power?
Thanks, you guys are the best.