[Sca-cooks] potash leavening

[Terry Decker]

Lye (caustic potash) is the liquid produced by leaching wood ash containing 
potassium hydroxide.  Potash is the potassium carbonate produced by 
evaporating lye in a pot.  The chemistry is rather complex (which means I 
don't fully understand the process), but drying the leach concentrates 
carbonic acid that in turn produces a high percentage of potassium carbonate 
in the solids.  When exposed to water in the dough, the potassium carbonate 
reverts to potassium hydroxide freeing carbon dioxide.

Use of the term potash in English begins in the latter half of the16th 
Century, so its use in German and Dutch predates that.

The lye in German baking is as a solution brushed on the crust to alter the 
crust in the baking process.  Potash is used as a leaven.  Without some 
accurate records, there is no way to tell how the two are related other than 
both result from leaching wood ash.

Bear



> Bear replied to Kirk with:
>> >>>
>> Has anyone tried hardwood ashes in quickbreads and such, I have a few
>> receipes calling for them as a leavener, and was wondering how well they
>> work.
>>
>> Kirk
>> <<<
>> What you are after here is potash, potassium carbonate, which was 
>> originally
>> leached from wood ash.
>
> Is this liquid leached through the ashes, lye? I seem to remember those 
> directions as the starting point for making soap.
>
>> If the authors of the recipes are really calling for
>> hardwood ash, then they probably didn't know what they were talking 
>> about,
>> since you need to concentrate the potash for it to be effective.
>
> How? Boiling it? Or putting the solution through the ash several times? 
> The latter is what I seem to remember from soapmaking directions.
>
>> Potash leaven is primarily a Dutch and German thing.
>
> Prior to 1600 CE? Or only later?
>
> If this solution is indeed lye, I wonder if there is a connection to the 
> use of lye in such things as pretzels and bagels? Because those were of 
> German origin, right?
>
> Stefan