Is it a single reaction slow raising agent? It only activates when on a heat right?
My product is a Chinese fried dough known as youtiao... And also going to add with ammonia bicarbonate
A quite readable explaination from a supplier of leavening agents : http://www.lallemand.com/BakerYeastNA/eng/PDFs/LBU%20PDF%20FILES/1_12CHEM.PDF
According to them, sodium acid pyrophosphate has indeed a "slow to very slow action, slightly bitter aftertast". But the bicarbonate will produce CO2 when reacting with the acid, regardless of heat.
I wouldn't use ammonia bicarbonate as its "ammonia taste limits [it] use to low-moisture products" : your batter might still contains too much moisture to get rid of the ammonia taste.