Soakers & Botanical Dogma
I'm a 'returning' baker. I did a short tour of duty at friends' Tassajara-inspired breadshop startup in the early 70's, but hadn't made a loaf since, until my son miracled me Lahey last year. NKB broke the ice, but didn't cut the mustard for flavor & texture. So I'm studying Reinhart, Magee, Buehler et al. to up my game. I have a question that none has answered. I apologize in advance for how long this post will probably be.
More preface: I teach university-level botany, including the physiology and enzymology of the hydrolytic reactions that release stored, polymerized substrates when a cereal seed imbibes water. Reinhart is warmly inspring in his fascination with enzymes and his consequent advocacy of pre-ferments. But there's something about soakers in particular that contradicts botanical dogma.
Imbibition of water by cereal seeds (barley being the longstanding research model here) allows the stored hormone gibberellin to diffuse from the embryo ('germ' in baker-speak) through the endosperm to its outermost aleurone layer where it binds to protein receptors in aleurone cells. That binding sets in motion a series of biochemical reactions that ultimately result in starch-degrading enzymes being made de novo in, and secreted from, aleurone cells. Among these enzymes are the amylases familiar to anyone reading this. Other stored polymers -- proteins, fats, nucleic acids -- are also hydrolyzed by newly syntheized and secreted aleurone enzymes. So far so good -- Botany 101 cereal seed germination physiology.
As far as I know, these aleurone-synthesized hydrolytic enzymes do not exist in desiccated cereal grains of the sort we mill into bread flour. They only get made (to be precise, translated de novo from messenger RNAs) in intact seeds that have imbibed water that allowed diffusion of the hormonal signal from the embryo. This implies that there shouldn't be any amylase enzyme activity in a soaker consisting of flour and milk, soy milk, buttermilk, etc., unless the milk introduces them. I don't recall any writers claiming that. So where do soakers' hydrolytic activities come from? Addition of yeast or diastatic malt changes everything of course. But I'm talking basic liquid+flour soakers.
On the other hand, if sprouted grains are used in a soaker, and perhaps importantly, if they are gently mashed first, to release these enzymes to better expose the flour's starch to them, then the latter might indeed be acted upon by aleurone enzymes to release simpler sugars (read: flavors) from the flour. (I'm dying to try this)
So why do soakers work? Starch-hydrolytic enzymes should not be present in them, because the cellular integrity of the seed that is required to initiate their synthesis is destroyed in milling. Empirically of course, soakers do work. It isn't the milk: I've used ultrapasteurized (Meijer organic -- good!) milk in my Reinhart soakers with delicious results. Ultrapasturization oughta nuke any enzymatic activities for sure. Is my dogmatic view of germination and amylases overly simplistic, ignoring rogue amylases conveniently present in milled grain? Or are these writers giving enzymes more credit than they're due, ignoring some non-enzymatic, physical process?
Sorry for the verbosity. Incorrigible. I have more questions, but they can wait. Thanks.
Hi, Toad.de.b, and welcome to TFL.
You pose an interesting question. I should warn you in advance that my education is in civil engineering and that I haven't seen a biology text, other than what my kids lugged home while they were still under my roof, in 35-40 years. Consequently, my response may not be as useful as you wish. If I knew the answer, I would provide it. Since I don't, I'm responding with questions of my own that will perhaps elicit further thoughts.
Is it possible that further investigation is required for your statement "As far as I know, these aleurone-synthesized hydrolytic enzymes do not exist in desiccated cereal grains of the sort we mill into bread flour."? Granted, the integrity of the germ and bran and aleurone are all destroyed in the milling process. Does that necessarily mean that the fragmentary remains of those components, particularly the aleurone, are incapable of producing enzymes as a result? Or that naturally resident microorganisms in the flour are restricted from producing ezymes of their own?
Short of irradiating flour samples, it is virtually impossible to eliminate some microbial presence. Milling temperatures are generally below levels required to pasteurize the flour. I don't know what percentage of native one-celled organisms (or aleurone cells) survive the bleaching process. I do know that grains aren't dessicated before milling; in fact, moisture is usually added to achieve a moisture level of about 14% to facilitate milling. It's true that farmers and elevator operators do dry the grains before sale to remove excess moisture that would lead to spoilage but the grains are still viable after the drying process.
I'm not sure if this gets you any closer to an answer but I hope that it will serve as fodder for further consideration.
Paul
I've thought about that Paul. Gibberellins should certainly still be present in whole wheat soakers, as they are presumably still present in the embryos happily littering whole grain flours. But so-called signal transduction in multicellular seeds is a pretty cellularized process. It's hard to imagine the gibberellin receptor finding its ligand (the hormone) floating around in a soaker and knowing what to do with it (all the downstream biochemistry). Getting an enzyme made means having all the protein synthesis machinery be intact, and that means an intact nucleus + cytoplasm, etc. That is, intact cells. So I don't see it happening without intact cells.
Yes, microorganisms naturally present in the flour -- they could do it, whole wheat or unbleached white. And I'm sure they're there (they're everywhere that we don't forcibly evict them from). Maybe I should borrow a plate of rich broth from one of our micro labs and streak some soaker on it to see what grows. There's gotta be a publication in this somewhere :-)
Great fodder. Thanks Paul
I'm not sure if this will help, as soakers can be made of just about anything. As far as milled flour is concern, millers add amylase from two sources: malted barely and Aspergillus oryzae, an amylase-producing fungi.
...a topic barley grazed by Reinhart and thus still pretty foreign to me. Thanks!
FWIW, I've used only Red Mill Organic flours. They don't say they add anything on the packaging and I've assumed there's nothing but powdered up wheat seeds in there. But like I said above, the bugs are everywhere. Mills are clean, but not sterile. Yeah, blame the bugs. Or thank them. It's their planet, after all.
Source. Hamelman. Bread. p. 369-370.
(My post was locked by your reply. I forgot to add the source of the information.)
SAUNDERS, H. NG, and L. KLINE quantified the sugars in a commercial flour in the paper at this link:
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&sqi=2&ved=0CB8QFjAA&url=http%3A%2F%2Fwww.aaccnet.org%2Fcerealchemistry%2Fbackissues%2F1972%2Fchem49_86.pdf&ei=-UILT6WJCMSWiQLswKiFBA&usg=AFQjCNEddjXkOVsr9smMj-297SCitZgypQ&sig2=8tZxN8SKE0woWuHOC20heQ
The sugars were present before hydration of the flour to form a dough, thus they are available irrespective of whether the miller adds enzymes or not.
If you want to check this, you can dry sterilize some flour with heat (190°F for 8 hrs should be enough to degrade any amylase enzymes) and make up two batches of starter - one using the sterilized flour and one using baseline unsterilized flour. Record the volume of each starter over a growth cycle and plot them side by side.