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Is it possible to create an osmotolerant sourdough?

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nicodvb's picture
nicodvb

Is it possible to create an osmotolerant sourdough?

Hi,


since my sweet tooth (as Andy calls it) demands quite high percentages of sugar I always have a big problem with my leavened cakes: my rye starter  and the preferments I prepare with it are not made of osmotolerant yeasts, and it shows... making a cake is always a pain and I always have to proceed in incremental steps.


I wonder if I can give life to an osmotolerant starter using a selective approach: continually refreshing a part of my starter adding a non trivial amount of sugar and salt. My guess/hope is that at every refreshment only the osmotolerant yeasts should survive and colonize the starter.


But now the questions:


-first of all: does it make sense? Does my idea have any chance of succeeding?


-how much sugar and salt should I use? Yesterday I refreshed with 10% of sugar  and a touch of salt and now, after 12 hours, the starter has doubled a couple of times (the second time after a stir).


-should I keep the amount of sugar and salt constant until the growth rate is high or should I raise the percentages every time in small steps?


-finally: what would happen to the lactobacilli? Would they survive or die? Would my starter lose its enzymatic activity and it sourness?


 


Debra, I really hope to read your answer! I'm also very curious to know what which yeasts are osmotolerant and their properties. Can you can point me to something to read, please?


Thanks.

jeremiahwasabullfrog's picture
jeremiahwasabullfrog

what an interesting question. Its certainly not a silly idea.


I suspect if you try it, you will know as much as anyone, but I'll throw in my $0.02 worth.


The only easy part of the question is


"Would my starter lose its enzymatic activity?".


If you mean the ability to break starch into sugar, then no such enzymes will be activated as long as there is plenty of sugar handy, which is the salavation of them, because if the organism isn't wasting energy producing enzymes that aren't needed, then having the enzyme isn't a disadvantage and they won't get bred out. Having said that, they won't be activated in your dough either as long as there is plenty of sugar, so it doesn't really matter.


On the other questions,


"breeding" or acclimatising a starter is a biological process, but there are chemical processes at work here too, and no amount of acclimatising will make the starter perform better under high osmotic stress than it would have under kinder conditions.


There will certainly be a shift in the microbial balance which will shift the balance one way of the other, and I would guess it would be a shift towards the yeasts, which would tend to make it less sour.


How high were you hoping to go in terms of sugar?


"should I keep the amount of sugar and salt constant until the growth rate is high or should I raise the percentages every time in small steps?"


if you don't have the growth rate you want yet, don't increase anything, keep it stable till you do, or you find out that its just not happening.


All up, I suspect you're in the realm of experimentation, and if nothing else, by the end you'll know something which no-one else does!


Just a guess, I suspect you'll basically end up with some intersting, nicely flavoured osmotolerant yeasts, but not necessarily anything much "sour".


Let us know how you go!


 

nicodvb's picture
nicodvb

Writing of enzymatic activity I was thinking more of the proteolytic activity rather than the amylolitic one, since the starter is meant to be used in sweet doughs where sugars are plenty.


I'm aiming at a percentage of sugar between 25 and 33% with respect to flour (in weight, of course), that is quite high:-)


I agree with you that I'd better not raise the percentage of sugar and salt until the starter performs as well as I like.


If the lactobacilli died and if the starter became nothing else than a culture for the new yeasts the cakes may end up being not as "light" as I'm accutomed at and the starter itself may end up being subject to molds. Yes, I could restore the right acidity and keep the starter repaired adding some vinegar, but the proteolytic activity would still be lost.


I'm also a bit concerned that I might be growing some osmophilic beast or mold or something scary... I need reassurance:-)


In the meantime the starter has grown much faster at the second refreshment with 10% of sugar than it did at the first refreshment.


I also made a liquid rye starter (150%) with the same method. The first one with 10% of sugar raised very slowly; the second refreshment with 15% of sugar raised quickly. Rye is always very mysterious. What the hell does it have inside? :-)


Am I correct in assuming that a more liquid dough leads to a lower osmotic pressure than a firmer one due to the lower concentration of sugar and salt?

nova's picture
nova

Add the sugar to the final dough mix....I frequently use 25% sugar together with 15% fat in my dough, when using a hi gluten flour...the starter is never the issue...the strength of the gluten is....in my experience, if you do not want to keep osmostolerant yeast on hand, sour dough works very well. Grow your sourdough as usual and then add the sugar to your final mix.
nova

jeremiahwasabullfrog's picture
jeremiahwasabullfrog

Am I correct in assuming that a more liquid dough leads to a lower osmotic pressure than a firmer one due to the lower concentration of sugar and salt?


yep


If the lactobacilli died and if the starter became nothing else than a culture for the new yeasts the cakes may end up being not as "light" as I'm accutomed


when you say cakes, do you mean a sweet bread, or a cake as in baking powder activated by the acids from the starter? If it is a quick chemical rise, and you want proteolytic activity to give you a lighter crumb, then there might not be enough contact time to make the difference? not sure how you're doing this, so I could learn something here.


 


In terms of whether you are going to lose proteolyic activity, as you've already alluded to, that probably depends almost entirely on how the balance of the culture shifts, rather than how the individual strains adapt.


I'm also a bit concerned that I might be growing some osmophilic beast or mold or something scary... I need reassurance:-)


I don't know enough to give you a definative answer except to say - I would try it:)


Jam doesn't grow anything very nasty though.


You might want to have a look around at salt raised dough. I think that relies on very osmotolerant beasts, not that I would want to try it!


 


 


 

RonRay's picture
RonRay

I posted 2 links elsewhere on TFL to YouTube videos that show how to make a very simple sourdough starter based on sugar, water, and instant potato flakes. The bread looked great, and while I did not make the bread, I did try making the starter and have maintained it for a couple months - I might add that it was the fastest sourdough starter I've ever made from scratch! It is loaded with sugar. You might want to check out the videos.


Potato Starter: http://www.youtube.com/watch?v=XkZ-q6P-ioA
Sourdough Bread from Potato Starter: http://www.youtube.com/watch?v=DnXZCuQoeio


Ron

nicodvb's picture
nicodvb

Jeremia: my intention is to use this starter in sweet bread, as in the traditional Panettone, Pandoro and Colomba of italian cuisine.


The typical recipe for the panettone I prepare requires 380 gr of high gluten flour, 4 yolks, 130 grams of water, 120 gr of butter, 120 of sugar, 20 gr of honey, vanilla and 300 gr between raising and candied fruits.


I read the thread pf the salt-risen bread, but I'm a bit scared by that strain of beasts.


 


My starters are going very well. I decided to refresh them only once a day because I don't want to add more variables (such as the headstart that yeasts get from early and repeated refreshments).


The rye starter at 20% tripled very fast as usual. It has a more orange-ish color and a more sour aroma, moreover its PH fell to an all-time low: 3.7 (24hours after the refreshment). Previously the PH never went below 4.0. Now I raised the percentage of salt+sugar to 25% wrt flour.


The high-gluten flour is going equally fast. Last refreshment was made 17% of sugar+salt and the starter tripled in 4 hours.


 

nicodvb's picture
nicodvb

I forgot to ask if you can explain how fats inhibit fermentation. Do they still have to do with osmotic pressure or for some other reason?


Thanks.

nicodvb's picture
nicodvb

At 20% the starter keeps on tripliing in ~4 hours, so it's healthy.


A couple of aspects that surprised me were the incredible acidity  (PH 3.5) and the massive amount of proteolitic activity. Apparently my fear of killing the lactobacilli wasn't founded, yet what is happening is totally unexpected. Who knows what's going on...


 


Can someone explain how fats hinder fermentation? I read something very synthetic still regarding the osmotic pressure, but I have the impression that the effect of fats on yeasts is not the same as the effect of sugar and salt.

Debra Wink's picture
Debra Wink

Hi Nico,


Sorry to take so long to get back to you. Better late than never, right? You've probably already figured some of this out on your own, but I'll weigh in anyway.


"Rye is always very mysterious. What the hell does it have inside?"


Pentosans. Pentosans are strings of 5-carbon, "pentose" sugars, in a similar way that starches are strings of glucose. Remember that lactobacilli produce more acetic acid when pentose sugars are available.


"The rye starter at 20% [added sugar] tripled very fast as usual. It has a more orange-ish color and a more sour aroma, moreover its PH fell to an all-time low: 3.7 (24 hours after the refreshment). Previously the PH never went below 4.0."


"A couple of aspects that surprised me were the incredible acidity  (PH 3.5) and the massive amount of proteolitic activity. Apparently my fear of killing the lactobacilli wasn't founded, yet what is happening is totally unexpected. Who knows what's going on..."


Actually, this isn't surprising at all. You added a fair amount of sugar---sucrose---which is a disaccharide composed of glucose and fructose. Lactobacilli love fructose, because it helps them squeeze more energy out of glucose and maltose. And in the process, they make acetic acid in place of ethanol. In other words, more acidity.


"If the lactobacilli died and if the starter became nothing else than a culture for the new yeasts the cakes may end up being not as "light" as I'm accustomed"


I think you're looking at this from the wrong perspective. Proteolysis is not your friend in the type of bread you're wanting to make. I agree with nova on this one---you want to keep the gluten as strong as possible, because the sugar and fat are already working against it. Lactobacilli are working against it. Unfortunately, you can't get rid of them.


"I decided to refresh them only once a day because I don't want to add more variables (such as the head start that yeasts get from early and repeated refreshments)."


Yes, you do :-)


"my intention is to use this starter in sweet bread, as in the traditional Panettone, Pandoro and Colomba"


Traditional processes generally come to be traditional, because they work and they've stood the test of time. A firm mother dough, refreshed frequently with only white flour, is what works for these breads, because this is the best way to reduce the number of lactobacilli in relation to yeast. It's the yeast that will raise your bread, and gluten that will trap and hold on to their gases. So, you'll want to do everything you can to help them.


Best,
dw

nicodvb's picture
nicodvb

Hi Debra,
I'm very pleased to read you intervention, for which I thank you.


Now it's very clear what's so special about rye and why the PH dropped more than usual, but I have a doubt concerning the proteolithic activity. I completely agree that the gluten is the structure itself of the raising, but I was under the impression that a modest proteolytic activity would (or could) result in a gummy crumb, even more so when using a high gluten flour (necessary for this kind of dough). Am I mistaken?


Finally, I think it's time to show how the puppy is doing. What better than some pictures to explain it? This is a pandoro, (very) sweet dough laminated with a lot of butter:-). Actually it's one of the most challenging sweet doughs I know because of the massive amount of fats, sugars, because of the consistence of the dough and for the lamination itself (a personal nightmare).


From the point of view of the raising I declare very satisfied: the culture raised the dough remarkedly faster than my other cultures, at least before the dough entered the fridge.


This is the best pandoro I ever made.



 



 


zoom of the crumb:



Again, thanks a lot!

PMcCool's picture
PMcCool

It looks as though you nailed the "shreddy" texture for the crumb.  Nice work!


Paul

Debra Wink's picture
Debra Wink

"I was under the impression that a modest proteolytic activity would (or could) result in a gummy crumb, even more so when using a high gluten flour (necessary for this kind of dough). Am I mistaken?"


Proteolysis isn't the only thing that can cause gumminess, but if/when gummy crumb is the result of proteolytic activity, I would call that excessive. When the gluten network develops so many holes from being clipped by enzymes that it gets leaky instead of just extensible, it stops expanding, and eventually may even begin to collapse. It's all a matter of degree.


A dough made from high gluten flour, having a stronger, more reinforced gluten network to start with, will withstand these negative effects longer. But to get the lightest breads possible from it, the best strategy is still to inhibit proteolysis and enhance lift by repressing bacteria and promoting yeast. You'll get more than enough extensibility from all the fat.


Best baking to you :-)
-dw

nicodvb's picture
nicodvb

Debra and Paul!


Debra, I take your word and will base the next work on it.