The Fresh Loaf

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Poolish Pride - notes on the zymurgy of set sponges.

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BvN's picture

Poolish Pride - notes on the zymurgy of set sponges.

I am a retired engineer, a baker of bread, and brewer of beer. This blurb is narrowly focused on what I have learned about the setting of sponge for the baking of bread (updated 6.May.09).

I have a very large supply of Saccharomyces cerevisia, the species of yeast used for baking. It is a by product of my brewing of ales. I cannot match the expertise and baking skills I have observed on this forum; but, I can contribute in this fairly narrow aspect.

The strain of S cerevisia is of little importance in baking. If it did, nobody would use instant or active dry yeast. Many students can attest, beer from these sources is not good. The bread turns out fine.

Stainless has no practical effect on yeast fermentation. Stainless steel is the rule for the construction of fermentation vats by both brewers and vintners. Yeast acidify their environment only slightly.

Oils and iodine (as in most table salt) are poisonous to yeast.. Small amounts MgSO4 (Epsom) & CaSO4 (Gypsum) cause no problems. Adding salts, is generally, a very bad idea.

Flour is a second rate food for yeast, they have to be starved into eating it (aclimate). Malt extract (malt liquor) is the finest yeast food. For baking, I recommend a dry malt extract - less than $5 / lb; almost a lifetime supply and it stores in anything airtight.

My understanding is that sponges differ from starters in that yeast propagation is not done with flour. Starters, quickly, get contaminated with wild yeast, molds, and bacteria - most commonly lactobaccilus which creates the sour dough effect. Maintaining a pure yeast culture is beyond the scope of this writing (at the moment). Good sanitary practices can maintain cultures for well over a year.

--- How I do it.

The objective of the following method is to impart a rich, full, and complex flavor to the dough without making it sweet. This is done by the maltose and dexidrines from the malt extract. It is more subtle than what occurs with sucrose, glucose, and fructose. The timing and measures are incredibly sloppy. Yeast can be very forgiving, if treated right. Minimize mechanical shock, thermal shock, light, and invadeing microorganisms.

I make as much sponge as possible. I put all off the dough's water requirement into my sponge.

Step 1 - Sanitize everything. Bleach water once, rinse twice. 1 capfull of bleach to a gallon of water.

Step 2 - Make lots of healthy, happy, well fed, yeast. Combine the water and at least 1 Tbs of malt extract powder for each 6 oz of water into a gallon jug. Temperature should be 75 ~ 85 F. Shake violently for a minute or so, to release the chlorine and to add oxygen (aerate). Decant into a bowl that holds twice the amount of water. I sort of add about 1 Tbs of yeast culture for each cup of water. It doesn't really matter as this is a propogation step, not a fermentation step. Cover and rest for 15 minutes to a couple of hours. The yeast will begin to reproduce very quickly. This is not fermentation, which is an anerobic process. Don't peek - at least not much. The longer this is left, the less maltose will remain and there will be more yeast to feed. You can add more malt extract at any time. The yeast are not as fussy about malt extract feeding schedules as they are about flour feeding schedules.

If using another source of yeast - split the water and follow the package directions. Add the malt powder, etc to the remainder. The source of the S cerevesia (yeast) is completly unimportant.

Step 3 - Make the sponge In a vessel, at least 4 times the amount of water (note: I use a small 2 gallon stainless steel pot with lid). Combine 1 cup of flour for each 12 oz of water - a very thin batter.

Step 4 - Set the sponge. Cover and keep warm 70 - 75 F for at least 6 hours. It can be kept for a couple of days without problems. If all goes well, the sponge will tripple in volume, and it will not separate. A fully set sponge will look uniformly bubbly and be very sticky.


ehanner's picture

I'm chuckling as I read your post BvN. I went to a brew pub with my son a few days ago to try to learn a little about brewing and the brewers environment. My son's friend is the brewmaster and they make some outstanding beers. We had a little more fun than I had planed on so I only remember a little of what I learned, if you get my meaning.

So if I understand your words above, you are creating a culture fed with malt and inoculated with "yeast culture". Is Instant dry yeast (IDY) acceptable for this? Also the malt extract, is it dyistatic or non dyistatic?

Then as far as using the sponge for rising and fermenting bread, what are the ratios that work to deliver the deep flavor you are striving for? Do you have a formula you like?

A bread as good as a well crafted IPA would be some kind of accomplishment. I await your reply.

Welcome to the Loaf BTW. I think you will enjoy the group.


BvN's picture

As far as I know, "active dry" and "instant" should work just fine - for bread, not beer :-). As far as the malt extract goes, the subject of diastatic is not of much use. This is the end product of enzyme action. SInce, I use a powder, I assume it's non-diastatic. The malt extract powder is easer to keep than malt liquor.

I am still working on the details. I have a pre-sponge in propagation stage as I write. My bread calls for 3 cups of water, so I put 3 cups of water (85 F) + 4 Tbs malt extract powder in a plastic milk jug and shook it  (aereated and de-chlorinated) for a minute or two. This liquid can be compared to a wort. I innoculated it with a couple of Tsb of my yeast culture and covered it. It's gassing off a bit right now. When my wife finishes cooking our pasta (for dinner), I'm taking the pot and creating a sponge in it. Hopefully it will have set by tomorrow morning.

The culture and sponge have been remarkably forgiving as to formula. Doubling or halving doesn't have as much effect as temperature and time,

My recipie for basic French calls for some sugar. It is too sweet. The malt extract creates much the same "mouth" but without the cloying sweetness. I've been using extra bitter in lieu of sugar in my Pizza sauses and such for decades. I was looking for a similar effect in my bread. It's too early to tell for sure, but I think I have found it.


foolishpoolish's picture

BvN, if I understand correctly what you wrote , your method of using malt extract (I presume non-diastatic?) maximises yeast population/activity by encouraging aerobic respiration and metabolism of the added maltose. Since the products of this are carbon dioxide and water, I'm not sure I understand how this results in a 'rich, full, complex flavour'. Perhaps you could explain further? 




DrPr's picture

This is very interesting. i was wondering how I could use yeast from a local brewery for my bread baking. However, I do have a question. You say that sourdough starters quickly becoming "contaminated" with wild yeast, molds and bacteria, including the lactobaccilus which creates the sourdough effect, and that cultures can be maintained over a year with good sanitary practices.  When you say "contaminated" you imply that wild yeasts and lactobaccilus are undesired guests, yet these are the very creatures we invite into our flour and water mixtures as they are necessary for the baking of sourdough bread. Perhaps I am misunderstanding your explanation.

Also, I am aware that starters are often maintained for multiple years. I have never encountered mold in my own starter and I am by no means a professional at this time nor do I have special equipment to maintain my starter. As for sourness, bakers easily control this by knowing how to feed the starter.

If your experience with yeast is from the world of microbrewing, I wonder if you find molds and other problems to be a regular part of brewing.  I would love to visit a brewery to see how beer is made (one day I will)!

Weatherwax's picture

I've done a little homebrewing and I'm fascinated to try your method.  I'm curious, though, about why it doesn't matter what strain of yeast you use for your initial slurry.  It seems like a baker's yeast strain would be acclimated to flour already, while ale yeast would really need the malt to raise the dough. All of which might make ale yeast good for doughs that call for a little sugar, but odd for ones that don't.

In any case, am I right in thinking that you are generally aiming at using your home-propagated ale yeast for bread?  It seems like it really would taste different.  Or is the difference in flavor coming mostly from the freshness of the yeast? Or the malt in the bread? This is probably a chicken-and-egg question, but I'd be interested to hear your opinion.

I'd also love to hear more about emptins.  Do you bottle them like Simmons, or are you just referring to a recovered yeast culture from a batch of beer?

I can see where this is leading me. It is leading me to spend five dollars on a tube of yeast, just to gratify my curiosity.