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.