>>21853514
>400mL Guiness
Why?

>>21853558
I’d say the alcohol evaporating below water boiling point would assist with leavening

>>21853558
Yeast

Interesting.
Buttermilk is the traditional acidic leavener helper for soda bread, but Guinness is a common alternative.
Buttermilk (pH ~4.4–4.8)
Guinness (pH ~3.9 to 4.3) is more acidic than many other ales

You can also use yogurt, sour cream, or lemon juice (mixed with milk).

>>21853629
There is no live yeast in guinness

>>21853558
>>21853566
>>21853629
Its the acidity, it creates a chemical reaction with baking soda which creates carbon dioxide gas to make the dough rise. The yeast in Guinness is dead and has flavor but does not act as a leavener.

Baking soda requires a chemical reaction with an added acidic ingredient.
Then it must be used quickly because the reaction starts immediately.
Baking powder is baking soda and an acid base; it will react when in contact with moisture.
Double-acting baking powder has baking soda and 2 acids, 1 that reacts with moisture contact and 1 that reacts to the hot oven temperature, which allows for delays between mixing and baking.