Properly prepared beer won't cause acceleration, if it did then some of the alcohol was still left in it. I simmer a 16 oz bottle of double dark chocolate stout down to 2-3 ounce then add that at emulsion. That way I don't have to mix the lye directly with the beer and I can reserve a bit of batter that has no beer for the head. This is my double dark beer soap, no FO or added color, just the beer.