noun
leavening agent; raising agent
A substance used in baking to make dough rise, such as yeast, baking powder, or sourdough.
パンを作るときは、膨張剤としてイーストを使います。
When making bread, I use yeast as a leavening agent.
このケーキのレシピには膨張剤とし
This cake recipe requires baking powder as a raising agent.