All grains contain peptides that mimic morphine or endogenous opioid substances. This is where I deal with my latest loaf craving. Get your bread-based exorphin fix here.

Wednesday, November 7, 2012

18% Rye Bread and thoughts about getting Stale






I made this 18% Rye Bread at Halloween.  It is the last bread I make before the kitchen is ripped apart, and I have no ovens, or counters, or cupboards, or even walls and floor for the next few weeks.

  • 82% ww
  • 18% rye
  • 72% water
  • 2% salt
  • 20% starter
  • 5% wheat germ




Why Write about Bread?
It has become old hat now for me to make bread on my days off, and to write about the bread (and what I'm thinking about as I make the bread).  Often the thought is about how to make bread better, or healthier, or my thoughts about food in general; sometimes my thoughts range far afield.  Occasionally I'm introspective.

Today I'm recapping for myself why I began writing about my bread.  I originally simply wanted to make a whole grain bread because I couldn't buy one I liked anywhere.  I wanted to learn how to make one myself.  I wanted to understand how others did it (or if they didn't make whole grain bread, why not?).  As I taught myself through recipes, and reading about bread, and grain, as I experimented, I discovered a lot of stuff I had never thought of before, and I began passing it on.  My curiosity drove me deeper into a lot of different subjects.

But why write at all, once one has a handle on making bread?  Why continue to write?  Why write in the first place?

Obviously, to me writing is a compulsion every bit as addictive as the bread I make.  And it began at a time when I sorely needed to express myself again in words, when due to the nature of my work, as a nurse in a hospital palliative care unit, I wasn't allowed to write much of anything that was significant to me.  Bread was a hobby, blogging about it became a way to discuss things that were everyday, but intrinsic to life.  It became  a way of expressing life in the midst of death.  My way of saying to the world at large, "I may be just talking to myself, but I won't be muzzled."  And I felt like I was being muzzled, at work.  I felt like I was told that I had to shut up and be silent, as I watched patients die, as I watched co-workers bear the brunt of the terrible emotional toll, as I watched the healthcare bureaucracy undermine nursing care at every corner.   Writing about bread became for me a distraction, a purpose, a way to reclaim some small core of silly personal meaning in a life consumed with everyone's ultimate meaninglessness.  It was a way for me to temporarily take my mind off things too profound to contemplate any longer.

So suddenly take all that away -- force me to eat only bread that I've managed to squirrel away in the freezer, in preparation for this season of no-oven, no-baking; stop me from writing, while my frozen stockpile dwindles; muzzle me, once again -- and what will happen?

I feel my patience wearing thin, my raw emotions numbed, my thinking growing as stale as my thawing bread.  Anyone following this blog will know that I've been fasting 2 days a week; now, not only am I refraining from eating bread on certain days, I will be stopping from writing about it, for the duration of the kitchen renovations at least.  Will my frayed nerves be able to take it?

Or will I just end the blog here, and move on to something different?


How Bread Stales
Ever since I visited Red Cat Farm to try Master Baker Christian Burdan's Passion Bread (and was astonished to see how quickly his loaves staled, compared to my own homemade sourdough loaves), I have been trying to research bread staling in my spare time.  

The wiki on bread staling is currently little more than a stub.  But as you can imagine, there is a LOT of information on this topic "out there."  The baking industry** has wanted to slow staling, since it represents loss (Gomez reported that "3% of the production of bread is returned for problems of staling in the shape of unsaleable bread," and I have conjectured that the true loss is much higher); so lots of dollars have been spent to study staling from virtually every angle imaginable.  

But the strange thing is, despite over a century of applied science, "bread staling is still not completely understood"  (D'Applonia).  Even defining staling can be tricky.  "Staling refers to all changes that occur in bread after baking" (D'Appolonia), and so "commences as soon as the loaves are cool, if not before" (Cornford).  

Some scientists have looked at staling as a continuation of the process that begins with mixing and baking.  Temperature changes are important to this process, and so oven temperatures, cooling and even freezing have all been studied for their effects on staling, as have pH and the micro-organisms involved in fermenting. 

Still, there remains a subjective element to staling -- we know it when we see it --  and Bales defined staling entirely in terms of customer organoleptic perception:

"The staling of bread can be defined as the decrease in consumer acceptance caused by changes in the crumb and crust undue to microbiological action. The percentage of consumer acceptability of white bread declines in relation to storage duration [8]. This is caused by a declination of bread’s sensory qualities as the length of storage increases [20]. Since eighty percent of bakery sales are impulse purchases motivated by perceived freshness [19], the qualities of bread that indicate freshness are crucial to any acceptable loaf."  

Cornford reported that "Differences of only 2% in crumb moisture are distinguishable by taste."  

While we do not require the many techniques that have been used (X-ray crystallography, electrical conductivity, digital imagery, differential scanning calorimetry, CP MAS (cross-polarization magic-angle spinning), DSC (differential scanning calorimetry), DTA (differential thermal analysis), MRI (magnetic resonance imaging), NMR (nuclear magnetic resonance spectroscopy), etc. ) to detect staling, these various scientific investigations have revealed a lot about structures beneath our perception, and a picture of the micro-processes involved (e.g. "increase in crumb firmness, loss of flavour, decrease in water absorption capacity, amount of soluble starch and enzyme susceptibility of the starch" (D'Appolonia)) is beginning to emerge.

Gray and Bemiller have organized for us and reported on much of the most important research done on staling, and is perhaps our best, easily accessed source.*  

"Bread is an unstable, elastic, solid foam, the solid part of which contains a continuous phase composed in part of an elastic network of cross-linked gluten molecules and in part of leached starch polymer molecules, primarily amylose, both uncomplexed and complexed with polar lipid molecules, and a discontinuous phase of entrapped, gelatinized, swollen, deformed (wheat) starch granules. Neither the bread system nor the staling process is understood well at the molecular level."  

In other words, it has long been known that "starch retrogradation is the most important single factor causing crumb firmness, but there are many contributing factors" (D'Appolonia).  

My understanding, based on my reading, is that bread crumb is a latticework of mostly gelatinized starch made up of interwoven layers of amylose and amylopectin, and this network is variously affected by the addition of fats and protein (whether from the grain itself, or as further ingredients of the recipe), some of which also bond to the starch, and exchange (attract and repel) water molecules (hydrogen and oxygen atoms).  The net also traps gases, which have been incorporated into the lattice through the mechanical process of kneading, and through fermentation, and these add to the network's structure upon baking more than to the later staling process.

How the bread lattice structure continues to change over time remains a mystery, and rheological models, foam models, chemical polymer models and models of kinetics have been variously used to describe it, as have the physics of emulsions and colloids. 

Often in the science literature one finds bread dough or a finished loaf described with the terms "dispersed phase," "continuous phase," "discontinuous phase," "elastic foam" and "crystal" and these refer to where the starch in the loaf fits in the hydrocolloid scales.  At one time or another, bread dough or baked and staling loaves will fit into one or more of these several categories.

Things get complex fast.  But it would appear that we still don't have an appropriate single model that will describe for us how crumb forms and firms during mixing and baking, and without that, we cannot hope to explain further changes due to staling that happen hours, and days, after the loaf is cooled.

It would appear that the amylose (20-30%) begins to retrograde almost immediately upon the bread's cooling, and this happens even before humans can detect it, within about 5 hours (Lee and Lee).  It is the retrogradation of the amylopectin (70-80%) layers that is detectable by us, and this happens over a time period of days.  It may be that in the first 2-3 days, water is leached from the amylopectin, and beyond 3-4 days, water is leached from the protein bonds, as the loaf stales further.  At least, we currently assume that the way the protein (gluten) interacts with the amylopectin, and how water is exchanged between the molecules, likely has something to do with the perceived staling.  

D'Appolonia created this triad of the main elements of bread to provide a visual aid to the interactions that are possible in how we may view staling.  Essentially, if we strengthen and/or optimise the elements that build bridges between the different layers to stabilize them, we can theoretically retard the leaching of water from one element to the next, and thereby slow staling:

What the home baker needs is not merely a list of ingredients that can be added to dough to keep it from staling (like what the Big Boys use).  Rather, we simply need a list of things to do that will improve the freshness and keeping ability of our loaves.  Unfortunately, there are a lot of variables, and even a table as simple as this is going to be true sometimes, and false at others.  This is the best I can do with what I know.


Action Increases
Staling?		 Decreases
Staling?		 Comments
Refrigerate Y
Experiments have shown that bread stales quicker in the refrigerator.
Freeze it
Y Stops the movement of water, which leads to retrogradation.  But when thawed, the bread will stale quickly.
Sourdough
Fermentation
Y Spontaneous sourdough fermenting decreases staling, if the sourdough starter is kept to a baker's % of around 20%.  At zero, or 40%, detrimental effects will be seen in the loaf firmness, and increased staling.  The mechanism appears to involve lowering pH, and may be yeast-specific, meaning certain wild yeasts may produce proteolyses, and some will produce amylases, which will affect the loaf.  It is suspected that hydrolysis of the starch (and thereby the production of dextrin, which interferes with starch crystallization) is involved, but experiments on this have so far been inconclusive.
More Lactobaccilus
Y Lower pH of dough through increased lactic and acetic acids brought about by natural fermenting generally decreases staling
More Pentosans
Y Wheat contains pentosans (non-starch pentose polysaccharide polymers), but rye contains more.  You can add some rye to wheat breads and it will improve staling.
More Fats
Y Neither grain's native lipids nor added oil or shortening will slow retrogradation of starch, but staling is reportedly slowed; the suggested mode of action is through the formation of lipid-protein bonds, but the full mechanism is unknown
More Glycolipids
Y The more glycolipids in the dough, the fresher the loaf appears.
Put it in the Oven again
Y It is well known that you can improve a bread's staleness temporarily by heating it in the oven again.  This liquifies the gums of the network of crumb structure -- but upon cooling, it will stale even quicker.
Increased Hydration
Y If there is more moisture incorporated, it will take longer to retrograde the starch.  The caveat being, it has to be incorporated into the structure of the crumb; the dough has to actually absorb it.
Adding Sugar Y
Adding sugar has an effect on the starch gels.  With increasing sugar concentration, the water's plasticizing ability is reduced, and the gelatinization temperature increases.  Disaccharides hydrate water molecules, and inhibit ice formation, leading to better freezing for doughs.
Increased Baker's Yeast
Y ? Lowers the firmness and the firming rate of the loaf, which is not quite the same thing as the staleness, but has similar organoleptic properties.
Increased Fermentation
Time		 Y
? Increases protease activity, which will affect the bonds of the proteins and starches.
Increased
Enzymes
Y Alpha-Amylases have been used alone or with other enzymes, to improve the staling of loaves.  Proteases, Lipases, Hemicellulases and Xylanases have also been shown to reduce staling over long periods of storage.
Adding Emulsifiers and Hydrocolloids
Y These are commonly added to store-bought bread these days.  On labels, you might see sodium stearoyl lactylate, monoacylglycerols, lecithin, carboxymethylcellulose, hydroxypropylmethylcellulose, alginate, diacetyl tartaric acid esters of monodiglycerides, etc.  For home baking, you might try adding locust bean gum, xanthan, whey protein, dried baker's yeast, and guar gum, if you must
Adding
Maltodextrins
Y Unknown mechanism; dextrins are formed from the hydrolysis of starch, and ordinarily hasten staling.  But adding dextrins may somehow keep starch molecules larger and intact for longer.
Adding
Fibre
Y Reduces bread staling, possibly because the fibre holds the water in place longer.


Results
This 18% rye was a fine bread.  It actually held up pretty good -- and I find that rye breads made with sourdough generally do not stale as quickly as wheat breads.  I suppose that this is because by adding rye, we are increasing the percentage of pentosans (non-starch polysaccharides, mostly arabinoxylans) in the dough.  This was only 18% rye, and it still had a positive effect on lengthening the time until it staled.  It lasted through a couple of fasts, so one loaf lasted all week long.

If I can manage on that amount of bread, I might just have enough loaves frozen to last me until I get my kitchen and oven back in working order.






Notes to Myself

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