The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Truth regarding LYES

copyu's picture
copyu

Truth regarding LYES

Hi all,


I'm getting tired of repeating myself on "Pretzel-Related" threads where discussion of "Lye" is concerned and I always have to resist the temptation to turn the whole discussion into a Chemistry lecture. I decided a few days ago to do a little "Kitchen Science" and do an incomplete, but slightly more detailed explanation of what alkalis are all about


What I wanted to do was examine some of the claims I've read here, and on many other pretzel-making/baking/soap-making sites. I got tired of reading YahooAnswers, where someone says "If you can't get Sodium Carbonate (Na2CO3), use Sodium BI-Carbonate, because they are very similar chemicals..." This is a true, but totally vapid and rather stupid statement. Common Salt, Sodium Chloride, (NaCL) is also a 'similar chemical' to Sodium BI-Carbonate, (NaHCO3) and similar to Caustic Soda, (NaOH) because they all have only one sodium ion, per molecule, when in solution...It doesn't mean they will perform similar chemical reactions on your bread or noodle dough, however


Understanding pH in detail isn't that straightforward or easy, but as a guide-line, pH7.0 is completely 'neutral' (or in balance) and it's the measurement you should get from pure distilled water. Lower numbers are found with sour, acidic foods, such as lemon juice and vinegar, around pH3-4. Numbers above 7.0 indicate a 'basic' or 'alkaline' property. Any liquid you test will be either acidic, [low pH, well-under pH7.0]; neutral [pH7.0 or pretty close to it]; or alkaline [pH higher than 7.0]


The problems arise when people fail to realize that the pH scale is "logarithmic" [or negative logarithmic] in the same way that dB [deciBels] are in electronics. This is an "engineering solution" to dealing with ridiculously big numbers. What this means is that the difference between one point on the pH scale represents a difference of a power of ten: pH8.0 is about TEN TIMES more alkaline than pH 7.0; a solution of pH9.0 is 100 times more alkaline; pH10 is 1000 times more alkaline, and so on...A tap-water reading in many cities around the world could be as high as pH8.5, which is also the most-often quoted pH figure for Baking Soda. Caustic Soda, or 'Pretzel Lye', on the other hand (one of the strongest known alkalis), is at least 5pH points higher, meaning that it is at least 100,000 times stronger than baking soda. It is this which allows the alkali to attack the surface starch of your pretzel dough quickly and that gives the brown color and the perfect crust that many pretzel fanatics love!


What I did was make solutions using 'Aqua Purificata', the nearest thing you'll find to pure, ion-free, distilled water at a reasonable price. I measured 3g each, using my most accurate scale, of Baking Soda, Kansui Powder (the ingredients of Chinese Lye Water) and Caustic Soda (or 'Pretzel lye') and mixed the powders with 100g of purified water. I mixed each solution for two minutes in brand-new plastic containers, rinsed with the pure water and dried with heavy paper towels. I measured the pH using an $80 pH meter that is fairly well-calibrated. After 3 minutes in each solution, I took photos of the meter readings. I now think I should have delayed the photography until 5 minutes had passed, but the pics I have will give you an idea of the differences among the three main chemicals I tested


http://www.flickr.com/search/?q=different+alkaline&m=tags&w=71323838%40N00&z=m&s=int


I hope this is clear enough and useful to somebody,


Best,


copyu


 


 

Comments

charbono's picture
charbono

Thanks for the test results.

The next time you have your meter calibrated on the basic side, you might want to test CaOH. Someone posted here about a year ago that he had tried it while making bagels. It worked a lot better that baking soda and almost as well as lye.

For those who don’t know, CaOH is calcium hydroxide, commonly available in food grade as “cal” or pickling lime. Although it has a high pH, it’s pretty safe to use. The solubility is quite low.

copyu's picture
copyu

I hope it wasn't too long-winded...I tried to keep the 'Science' down to home-kitchen level. However, I would guess that there are many kitchens around the world that do NOT have a pH meter in the top drawer... ;-) That's why I thought it might help


Thanks for the info about Calcium Hydroxide...I've heard and read of 'pickling lime' but have never seen it for sale, (except, perhaps, in hardware stores! It wasn't 'Food-Grade', though!) It should be basically [a pun! HAHA!] the same stuff 'chemically' as builders'/bricklayers' "Slaked Lime", if I'm not mistaken...?


Cheers,


copyu


PS: Just wondering, though, about the chemical formula...Ca(OH)2 would be the way to write 'Calcium Hydroxide', I think? [I could be wrong, of course...copyu] 

EvaB's picture
EvaB

and yes lye is much stronger than soda pickier to use too!


However I think a whole lot of fuss is being made over the lable food grade, and when its actually thought about, its only purified to some standard somewhere, and who says what that standard is?


My mo9ther used plain old Gillete's lye off the shelf in the store, she used it for cleaning pots (not aluminum, it eats that) making hominy (corn soaked in lye solution to dehull it, commonly used for masa harina in the southwest and mexico) and for making soft soap for washing.


My brother liked using just plain old lime (you can't buy slaked lime in Canada at least here in BC, since there was a serial killer who buried his victims in slaked lime) he just bought a bag of lime at the building hardware store, and used a small amount in the water to dehull dried corn for hominy. And NO ONE DIED FROM IT!


Lye was a common ingredient in Colonial times and even into the early 20th century, its easy to make, and you can purify it simply by wahsing the lye chrystals several times and allowing them to rechrystalize each time.


Easiest method is to burn some nice clean wood (no garbage, and no collected waste wood that might be contaminated) take the ash, and make a box on one end of a plank of clean untreated wood (maple, or oak would be good) This is made with the same wood as the plank, The end of the box towards the end of the plank has several small holes drilled along the edge to allow water through. This all requires a safe place to put this out of the reach of children and pets. Then you put the whole thing on a slight slant over a bucket (stainless steel or wood, possible a food grade plastic) and put your wood ashes into the box, and water, gently or you will have ashes in the lye! Let the water drain through the ash, adding more water for several days, the holes should not be large, just enough for the water to drain slowly out. Replace the ash as often as you wish, then when you have drained all the water through, you will have a bucket of probably rather grey looking water (DO NOT TOUCH) pour this out into shallow pans, and allow to evaporate, this you can strain through a clean muslin cloth, not cheesecloth, it needs to be a tightly woven cloth, and the cloth needs to be washed out imediately or the residual lye will eat it! This should take out the grey from the charcole, and then the resulting chrystals will be lye.

charbono's picture
charbono

Thanks for the gentle correction of my calcium hydroxide formula.  "Cal" is found in Mexican markets.  Pickling lime is found in the canning section of supermarkets, sometimes only seasonally, and less often than in prior decades.


The base called wood ash is potassium carbonate; not everyone calls it lye.


Here is a study which shows lime pH at about 12 and wood ash at about 11.


http://www.springerlink.com/content/n1614663835863v1/


 


 

mgbetz's picture
mgbetz

*Very* helpful discussion, no lie! (lol)

copyu's picture
copyu

...and this subject is just 'begging' for some good puns, isn't it?


Nice response. Thank you very much!


Best,


copyu

copyu's picture
copyu

Most dentists use Calcium Hydroxide [Ca(OH)2] in their work and they often write its chem formula as 'CaOH', too, in their surgeries and on the internet. I just assumed it's a good 'short-hand' for professionals...Ca = Calcium...OH = Hydroxide, so...NO PROBLEM!


Still, it doesn't 'balance' chemically and I am a bit of a stickler for the things I do know...you were not 'wrong', at least according to the bad-old-internet, and everyone knows exactly what you meant...good communication, bro! That's what is important!


Your link was very informative


Thank you very much, charbono, and best wishes,


copyu 

breadforfun's picture
breadforfun

Since I've dabbled into making pretzles, I've experimented with a few things.  I came across an article a few weeks ago from food science and lore expert Harold McGee (On Food and Cooking) and urge you to read it.  He suggests baking the baking soda (no this is not redundant).  Chemically, when the soda is baked at 250-300 degrees, the bicarbonate breaks down and gives up water and carbon dioxide, yielding sodium carbonate.  The result is a much more alkaline product to use in cooking.  It is easier and safer to handle than lye.


http://www.nytimes.com/2010/09/15/dining/15curious.html

breadforfun's picture
breadforfun

[Sorry, but unless I misspelled pretzels above it triggered a spam filter.]

copyu's picture
copyu

Thank you very much for the link.


I've seen the article before and someone else explained that very technique, here on TFL, to which I responded about a week ago. I'll read the article again, though, so thanks


Sodium Carbonate is the major ingredient of "Kansui Powder", which also contains Potassium Carbonate. It is approximately 1000 times stronger (more alkaline) than Baking Soda, with a pH of around 12, while Baking Soda hovers around pH8.5--about the same as untreated alkaline tap-water in many cities.


Na2CO3 is strong enough to make soap, so it might even work as a paint-stripper or drain cleaner and I wouldn't doubt anyone who said it's useful for pretzel-making.


The only question I would have concerns how long people would be prepared to wait for the oil in paint to 'saponify' (turn to soap) or for their drains to run smoothly. (There may be serious timing issues with pretzels, as well?) Since I have access to a reasonably large range of alkalis, I just use the recommended stuff; Baking Soda (or B-Powder) for American biscuits and deodorizing; Washing Soda in the laundry; Sugar Soap for removing grease from painted surfaces; Kansui for noodles and Sodium Hydroxide for pretzels, etc


I'm sure many TFLers would be reluctant to use NaOH, or might have trouble sourcing it, so it might be just the right option for some people. Notice, though, that the article says to dip the pretzels in Na2CO3, for 3-4 minutes! NaOH will do the job in 15 -20 seconds.


Thank you and best wishes,


copyu

copyu's picture
copyu

I'm wondering how a 'simmering' solution of Na2CO3 would go...


I certainly wouldn't want to go to the trouble of making pretzels, just to have them dissolve or come 'undone' by sitting in an alkaline liquid for several minutes. I remember I used to simmer my pretzels in baking soda, about 25 years ago (just as all the recipes I had told me to do! Most of us didn't have the internet back then) The results were always delicious, but also slightly disappointing, due to the texture


I still have some of those old recipes and books. They say to 'simmer the pretzels until they rise to the surface...' That took less than 30 seconds, if I'm remembering correctly...It could be worth a try with some sodium carbonate doing the work...Anyone got any thoughts on the simmering?


Cheers,


copyu


PS: As for making Na2CO3; I can buy Kansui powder for about $1 per 30g (1oz) sachet and that would make a decent  one-litre solution. I reckon that might be cheaper than roasting a trayful of baking soda in the oven...at least here in Japan. copyu


 

breadforfun's picture
breadforfun

I typically boil or simmer pretzels for 1-2 minutes.  I have never experienced the dough dissolving.  It is a pretty dry and firm dough.


You are lucky to be able to buy Kansui.  Here I can buy 10 lbs. of baking soda for under $5, so this option works.