The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Leftover starter properties

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GregS's picture
GregS

Leftover starter properties

I've seen recipes using leftover starter, English Muffins for example, but I'm not sure if there is supposed to be any activity in the leftover. Some of what I have saved looks like a proteolytic goo. I'm sure there are bacteria in there, but is that important or is the remainder just a flour/water paste?

GregS

Ford's picture
Ford

Refresh it and see.  After all, if the starter raised your bread the left over starter should be active as well.

FlourChild's picture
FlourChild

Often times leftover starter is a sticky, gooey flour/water paste with questionable yeast activity and a lot of acid.  Most recipes that utlize it add additional flour to take care of the sticky/gooey part and then use baking soda both for leavening and to neutralize some or all of the acid.  I freeze my discards and then when I have enough, use them for pancakes.  If I want mild pancakes I use more baking soda to neutralize the acid, and if I want tangy pancakes I switch some of the baking soda to baking powder (multiplying by four to get same leavening power).

Frequent Flyer's picture
Frequent Flyer

...in a buttermilk biscuit recipe - strictly for flavor.  I use 1/4 cup starter per 2 cups flour and dissolve the starter in a scant cup of buttermilk before adding to the dry ingredients.

FF

cooperph's picture
cooperph

Hey guys, I am trying out using some leftover, i.e. rather inactive, starter as a replacement for some of the flour and water in a no-knead recipe. I keep my starter at a 100% hydration level. This one is for Einkorn flour, which is what I feed my starter with, and uses an 10-14 hr rise with 1/4 tsp AD yeast for 600g flour, and about 415g of water (1 3/4 cups). I simply assumed that my leftover starter, which was actually deliberately created just for this purpose and had displayed a very small, but non-zero amount of activity in the fridge, was still 50% water and 50% flour. I used 300g of the leftover starter and so reduced the flour and water by 150g each. My dough/batter came out noticeably wetter than usual (haven't eaten any of the bread yet) but I am thinking that in this leftover starter, the yeasts and bacteria having pretty much completed a "life-cycle" already, some of the flour had effectively been "eaten". This would make the ratio of water to flour more than 50% by weight.

Does anyone have any knowledge on this? I'd like to adjust the recipe, but would prefer not to just do it by trial and error, or "feel". I'm wondering if there is some way for me to measure the water content accurately? A colleague suggested taking an accurately-known mass of the starter, drying it out completely somehow, and then measuring the dry mass, then inferring the water from that. I'm going to try this, as I have a very accurate scale (0-100g in 0.01g increments, plus a set of calibration weights).

Will report back but thought I'd put it out there for comment also.

FlourChild's picture
FlourChild

I doubt that the starter is actually gaining more water.  With sourdough starters, there are enzymes that break down proteins and starches in the flour, and in the process make the dough seem much more sticky/wet.  I keep a 60% hydration starter which feels pleasantly firm and dry when first mixed, but after 12 hours of fermentation it is a soft, sticky mess.  This process is less noticeable in a wet (100% hydration) starter because the starter is liquid to begin with, but the same sort of enzyme activity goes on.  Some would argue that it goes on even more robustly in a liquid starter than in a firm one.

To compensate in your no-knead dough, you can either reduce hydration a bit, and maybe also reduce the quantity of sourdough starter used in the dough.  You may also need to reduce the amount of time that the no-knead dough ferments, as the starter is probably still somewhat active.  

You might also consider freezing the leftover starter when it is first discarded, both to arrest the enzymatic deterioration of the flour and to kill off some of the microbes, so that it is less active once added to your no-knead dough.

cooperph's picture
cooperph

Well, as the great Debra Wink explained in extreme detail here:

www.thefreshloaf.com/node/10375/lactic-acid-fermentation-sourdough

The life-cycle of of the sourdough culture should lead to an increase in liquid content, if not water exactly. The fermentation process is twofold, sugar is converted to ethanol and carbon dioxide by the yeast present, while the bacteria ferment sugars into various acids and other alcohols, and carbon dioxide. So the end result once the culture has consumed most of the readily available sugars will certainly be more liquid than at the beginning, with various acids and alcohols having been produced.

I am currently trying to dehydrate a 100.11g sample of my starter, simply by leaving it in the oven at 170F, which is the lowest temperature setting on my oven. Once I have reduced it to a bone dry powder, I'll weigh that and I'm expecting it to be less than 50.05g. My guess is something like 35-40g.

Mini Oven's picture
Mini Oven

the powder will still contain about 10% or more moisture yet feel dry.  If left to room temp to cool, depending on relative humidity it may be more.  Most flours contain roughly 14% humidity on the store shelf.  As you are weighing the solids, I will guess that it weighs more than 50g.  Maybe 55g.  Weigh it when hot and dry and after it has stood out to cool.  

I think if mixed it with equal weights water and flour, it is still pretty much the same unless it isn't covered, alcohol will evaporate along with some of the water.  170°F will certainly kill the yeast. and most delicate bacteria.  Can also be done without the oven.  Spread thin on parchment or plastic, peeled up and turned over.  The yeast will retreat into spores and take a few days to awaken when hydrated.  If the powder is used as flavoring, it won't be competing with added yeast for a while and may work as a dough enhancer.

cooperph's picture
cooperph

Shoot, I think you are right that I'll never be able to dry it out enough to get a useful answer.

I guess unless I want to do some serious literature research into the matter I'll have to just proceed by trial and error, combined with the feel of the dough. The way a real baker should!