Why using ammonia bicarbonate and baking powder for deep fried bakery product? This is my main bakery product:
https://en.wikipedia.org/wiki/Youtiao

I have been importing the raising agents. But now I can't import anymore...

From my experience, the recipe used 2 kinds of raising agent:


ammonia bicarbonate
baking powder (they only write down sodium bicarbonate and doesn't write the leavening agent)


And the sodium bicarbonate, I think it is a slow raising agent that only activates by heat. Because when I mix the baking powder with normal temperature water. There are no effects. But when I pour with hot water and stir with boiling water, lots of bubbles coming out, and rise up.

So my question is:

1.why they use 2 types of raising agent? Ammonia and slow acting baking powder (we deep fry the product in 200°c)

2.the dough, have a quite a few small holes after we rest 6-8 hours on freezer, is it because of the slow raising agent baking powder?

3.how to make the baking powder? I'm planning to combine sodium bicarbonate and sodium acid pyrophosphate... how much is the ratio?
1) the various ionic interactions with proteins in the batter can determine its characteristics. 

Some information are at https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/leavening-agent

I can't judge if a model can be really draw out of it but using different mixtures of salts in baking powder formulation reasonably leads to difference.

This is already a comment to your other recent question.

2) Both ammonium and sodium bicarbonate are the leaving agents. Different to yeast in which gas and volatile compound are results of the little organisms metabolism, using the above salts is based on their thermal decomposition. The leaving effect is due to carbon dioxide and ammonia released at the high temperature concomitant with frying/baking. There is no need to wait for raising a dough, with chemical leaving agents.

Unless you need a very special formulation, you should be able to reproduce the previous results without importing anything. Just experiment with the ratio of the two and it should be fixed.