The conversation between human and AI assistant.
[|Human|] Extract the different kinds of leavening agents mentioned in this passage. Separate them with a comma.
[|AI|] sourdough, baker's yeast, barm, purpose-cultured yeast, commercial yeast, baking soda, cultured yeasts, bread improver, flour improver
[|Human|] 
Extract the different kinds of leavening agents mentioned in this passage. Separate them with a comma.