Tequesquite as a baking ingredient -- from the Pinedo cookbook

An interesting ingredient that appears in Encarnación Pinedo's cookbook,  El Cocinero Español, is tequesquite.  I had never heard of it when I began translating the book, so I did some reading to learn more.

Here is what she had to say on pages 264-5:

My Translation

Miss Pinedo gives several recipes that require tequesquite, listing it as just tequesquite or as "settled tequesquite water."  It is used as a leavening agent in breads, pastry dough, and a fruit-based bread pudding.  She also uses it to remove the skins of garbanzo beans before they are added to beaten eggs to make a "torta" or omelet.

Searching around the internet, I learned this from a translated article on the history of tequesquite:  https://es-us.noticias.yahoo.com/tequesquite-cu%C3%A1l-uso-cocina-110954296.html

This alkaline salt was sold in rock or ground form.  Among the many uses of tequesquite, the one that stood out was seasoning food, just as it is done with common salt today.

When adding salt to food, pre-Hispanic groups noticed that it helped to soften legumes.  From there, its use began to soften corn and bean kernels, adding the powder to the water during cooking, a use that is still given, as well as to cook herbs or nopales, since it softens them while maintaining their natural color, in addition to help their digestion.

Inside the kitchen, the discovery of the properties of tequesquite continued, as it was noted that whether in powder or mixed with water, if added to corn dough, it worked as a leavening agent, which helped the tamales and other preparations "sponged", a function similar to what baking powder does today, while, in addition to its culinary uses, tequesquite was used as a detergent in the homes of pre-Hispanic Mexico. 

This site, https://gustausted.com/2019/12/el-tequesquite-que-es/, added more information:

Tequesquite serves as yeast.  For this purpose, this decoction is prepared:  ten transparent green tomato peels and a tequesquite stone are boiled in a cup of water.  Once the latter is broken up and the water has come to a boil, it is removed from the heat and allowed to settle.  When it cools, it is strained and that little water is added to any dough to make it fluffy.  In the center of the country it is customary to add it to the dough for tamales.

I was concerned about making the mixture with tomato peels, as Miss Pinedo did not discuss that at all.  I appreciated the reference to allowing it to "settle", as that matched with her words.  

I kept looking, and then I came across video food blogger Max Miller, where he shows how to make tequesquite water here:  https://youtu.be/NPxjQetKPoo?t=298.  To quote from the video:  "Use 1 tablespoon of tequesquite powder and pour over 1/2 cup boiling water.  Let it settle, let it cool, and then skim off the water, leaving the rocks on the bottom behind."

So I was convinced that I did not need the tomato peels.  I was also curious about what, exactly, was in tequesquite, and I found this information from a science article analyzing tequesquite composition:  https://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0188-62662016000500031

From its introduction:

In former Lake Texcoco basin, salinity of natural water outcrops can reach up to 80 g/L to 90 g/L in the dry season, so salt crusts covering extended areas can be observed.  These crusts are called tequesquite (from nahautl tetl: stone, and quixquitl: sprout, sprouting stone), a mineral complex that has been used in Mexico since pre-Columbian times to cook and flavor foods like corn, cactus pads (nopal), and beans.  Nowadays it is still commercialized in some local and regional markets as little stones.  Importance of tequesquite in other parts of ancient Mexico is mentioned by Williams (2010), in Lake Cuitzeo margins, where this mineral was also collected and commerce for human consume [sic].

 Tequesquite is an amorphous and solid material, crystallized or in powder form, that depicts varying colors ranging from white to dark-grey, depending on the degree of purity and clay content.  It is classified in five categories with the following local denominations:  confitillo, cascarilla, espumillo, polvillo, and dark tequesquite, depending on the collecting season and place of origin.

The article presenting a chemical analysis: 

And gave us a discussion of the results:

Traditional use of tequesquite in Mexico is mainly in food cooking, after its solubilization in water to eliminate clays, sand and other impurities that could negatively affect the quality of the processed food.  ... [T]equesquite's solution contributes with sodium and potassium ions, responsible of salt taste otherwise added as NaCl during cooking.  Concentration of bicarbonate and carbonate and high pH value (related to NaOH and KOH content), act as softener of hard seeds and cactus and help to preserve a vivid green color in vegetables.

Presence of NaCl and Na2CO3 in tequesquite samples agrees with incomplete composition reported previously and explains (at least partially) the reason for its culinary use in Mexico.  As is show, no toxic elements were detected that could question culinary use of this saline complex.

I was pleased to see that I didn't have to consider toxic elements.  

One day I found tequesquite for sale in a local Mexican market.

At this point, I had not read much on the ratio of powder to water, but I did try to make some settled tequesquite water.  First I mixed water and powder together (sorry, I didn't really measure the amount of powder).  I used 16 ounces of water and several large spoonfuls of powder.

Once I had stirred it and felt that something had dissolved into the water, I strained the mixture.  My goal was to decant the liquid and leave the chunks behind, which I did with good success.

The floaties that were strained out.

The chunks that were left behind

So now I had tequesquite water, but I needed to let it settle.

Unsettled water

I did not know when I would use it, so I labeled the container and left it, mostly undisturbed, in a cupboard for a long time.

Settled.  See the grey at the bottom?

Of course, I had to taste it.  It was not salty, as I expected, but only mildly so.  Mostly I tasted what I think of as alkaline water.  It was strong but not off-putting.  The taste was not appealing, but it was not awful, either.

I had no idea if it was strong enough to do the job.  What amount would go into a recipe?  I found one recipe on the internet that gave me an idea:  https://www.mexicanrecipes.me/SantaRitaEmpanadas.htm

I suspect my mixture was not considered strong enough, but there was only one way to find out.  I needed to make something!  See the next post for that experiment.