do all sourdough starter cultures become the same?

[Jackie Tran]

Okay Craig, I will keep the CY leaven going just for giggles, but will also start a room temp starter that I am familiar with to see if it will change in 2-3 weeks time.  Since I am committed to feeding it routinely twice a day, I should be able to detect any changes in flavor of the raw starter.

Do you think baking flour above 250f would affect the way the starter (yeast) uses it?  Also it would only make practical sense to bake a big batch of flour for multiple feedings.  Do you think that keeping this baked flour at room temps would allow bacteria to regrow in the baked flour?   It seems impossible or at leas improbable to sterilize flour of bacteria.

Chau

[JimmyG]

Chau,
I like the idea of using IDY, CY or any other commercial yeast culture as an experimental and control for a preliminary study like this one. I think the next stage would be to test sourdough culture like Craig is suggesting, however, I think it is important to have some sort of a baseline to compare your future result too.
If you wanted to ensure contamination from flour is not a contributing factor, I would think that the participating experimenters could heat some water–using one of the dough temp formulas posted on this forum– to 130F or above (where it is known to kill off sourdough microbes), add the heated water to the the flour, let it sit for 30 mins or more, like a standard autolyse, and then add in the yeast or culture once it has cooled to room temp. Hopefully, this would minimize any contamination from the flour and not interfere with the proteins in the flour at these low temps.
At this stage, I do not think it is important to worry microbe variety as none of us, myself included, are able to isolate changes in the flora at this time, only changes in taste and performance. If we do consistently find some differences, I can contact some folks in the biology or food science depts to look into the mater. Other than that, I think it sounds like a solid plan.  
  
BTW, what you're outlining for what you are wanted to do and how you are justifying it is very scientific for an unscientific experiment  .

[TXCraig1]

Do you think baking flour above 250f would affect the way the starter (yeast) uses it?  

I don't know. It might have an effect on the carbohydrates that could change it's value to the yeast and bacteria. If it was much of an effect, I'd think you'd notice it quickly.

[Jackie Tran]

With the aggressive discarding and feeding schedule you proposed, will you not keep the pH artificially low? If a low pH is a component of a healthy culture, and I believe it is, perhaps you give an artificial advantage to organisms that can't survive in a low pH environment - opening a door that would otherwise be closed?

Why not feed on a schedule typical of what one might ordinarily find? Once every two or three days or so, discarding and feeding 50%. Whatever Ed Wood reccomends is probably a good choice.

Craig, I might be mistaken here, but the idea with my proposed feeding schedule is to consistently keep a healthy and relative young starter.  So one that is probably more moderate in pH levels rather than artificially low.  I'm wanting to keep a relatively low acidic starter.  I was hoping to avoid feeding it every 2-3 days as I thought that would create a scenario whereby the food source was dwindling or gone and the over acidic environment would be inhospitable for the yeast.  I am somehow picturing this scenario to weaken the yeast culture thereby making it easier for a take over.  This is what I was hoping to avoid.   Sorry if my thinking is backwards here, but am I misinformed here?

Again with the proposed feeding shedule, the seed is only 8%, so it would slowly ferment over 12 hours and should be active around the 12th hour or at it's healthiest state.  

Chau

[TXCraig1]

If you wanted to ensure contamination from flour is not a contributing factor, I would think that the participating experimenters could heat some water–using one of the dough temp formulas posted on this forum– to 130F or above (where it is known to kill off sourdough microbes)

Some starches start to gelatinize around 130F.

[JimmyG]

Craig,
I am going to have to go back and find the source but if I remember correctly, wheat starches in general do not begin to gelatine until 180F during the baking process.  Corn, potato, rice and sorghum, if I remember right set at 160 or below negatively effecting dough volume and oven spring.

[TXCraig1]

Craig, I might be mistaken here, but the idea with my proposed feeding schedule is to consistently keep a healthy and relative young starter.  So one that is probably more moderate in pH levels rather than artificially low.  I'm wanting to keep a relatively low acidic starter.  I was hoping to avoid feeding it every 2-3 days as I thought that would create a scenario whereby the food source was dwindling or gone and the over acidic environment would be inhospitable for the yeast.  I am somehow picturing this scenario to weaken the yeast culture thereby making it easier for a take over.  This is what I was hoping to avoid.   Sorry if my science is backwards here, but am I misinformed here?

I guess it depends on where you start. I think if you start with baker's yeast, yes, letting the pH drop will make a takeover easier as it will weaken the yeast. If however, the question is what happens to a sourdough starter, it think the opposite is true; by discarding and feeding large quantities often, I think you may keep the pH artificially high - not low. Sourdough species of yeast thrive in low pH - too low for other yeast to invade. That is a key part of the system.

This is why I don't see the value of a baker's yeast culture in this experiment as it is fundamentally different from sourdough.

CL

[Jackie Tran]

But if we heat the flour, won't that also kill off any yeast present in the flour thus making next to impossible for any take over to occur, assuming that the source of yeast for the take over is coming from the flour used for feeding?  

Again, the idea is to see if a takeover is possible at room temps using a somewhat normal and routine feeding schedule with regular flour.  We are seeing if we can recreate a takeover scenario that has been reported is probable.  I am fairly positive that these reported take overs weren't occurring with sterilized flour.

Jimmy, it's still a good idea though as long as the bacteria and yeast don't mind their food cooked.

[TXCraig1]

Craig,
I am going to have to go back and find the source but if I remember correctly, wheat starches in general do not begin to gelatine until 180F during the baking process.  Corn, potato, rice and sorghum, if I remember right set at 160 or below negatively effecting dough volume and oven spring.

It is a function of the amunt of water and other variables, but this indicates that the onset is around 130F. (Scroll up to page 294).
http://books.google.com/books?id=F9FoNy06qvcC&pg=PA300&lpg=PA300&dq=wheat+starch+gelatinization+temperature&source=bl&ots=WYvEw5Deap&sig=aHVZrYhIOSpvUqSsh_NWMAlCt60&hl=en&sa=X&ei=5wNwT-eVA6Oo2wXz-fzxAQ&ved=0CCYQ6AEwAA

[Jackie Tran]

I guess it depends on where you start. I think if you start with baker's yeast, yes, letting the pH drop will make a takeover easier as it will weaken the yeast. If however, the question is what happens to a sourdough starter, it think the opposite is true; by discarding and feeding large quantities often, I think you may keep the pH artificially high - not low. Sourdough species of yeast thrive in low pH - too low for other yeast to invade. That is a key part of the system.

This is why I don't see the value of a baker's yeast culture in this experiment as it is fundamentally different from sourdough.

CL

Good point.  Yes I want to keep the pH moderately low, not too low and not too high.  When I said that I wanted to keep a low acidic environment, I meant a moderate to high pH level, not a low pH level.  I did read that yeast thrive at slightly acidic environments, but just how acidic is the question.  I guess I want a culture that is semi active all the time, not under or over active.  So adjusting the seed amount so that the culture will become active quicker is easy to do if need be.  But even in a high a pH scenario, we are talking a 8-10% (of the new starter) seed versus dormant/inactive/ or weak yeast in the flour (the bad guys).  As long as a starter culture can become active in under 24hrs, I still don't believe the take over possible, at least not yet.  But here we are talking about the starter becoming active in 12 hours.  I can also adjust it down to 6hr if that would make everyone feel better.

I am trying to keep things as simple and fair as possible for everyone including the yeast.  JK, maybe not a great joke.  

[JimmyG]

But if we heat the flour, won't that also kill off any yeast present in the flour thus making next to impossible for any take over to occur, assuming that the source of yeast for the take over is coming from the flour used for feeding?  

 
Chau,
Good point! Especially given that most folk (myself included) will continue to keep their starter in the fridge regardless of the outcome. I'm sure, standard, unaltered flour will work just fine.
Any thoughts on pizza dough formula to apply this?

[TXCraig1]

But if we heat the flour, won't that also kill off any yeast present in the flour thus making next to impossible for any take over to occur, assuming that the source of yeast for the take over is coming from the flour used for feeding?  

Again, the idea is to see if a takeover is possible at room temps using a somewhat normal and routine feeding schedule with regular flour.  We are seeing if we can recreate a takeover scenario that has been reported is probable.  I am fairly positive that these reported take overs weren't occurring with sterilized flour.

Jimmy, it's still a good idea though as long as the bacteria and yeast don't mind their food cooked.

That's why I only wanted to use sterilized flour for one side of the test. That way if the non-sterilized fed culture changed and the other didn't, we'd have a pretty good indication of the source of the invading flora.

CL

[Jackie Tran]

Chau,
Good point! Especially given that most folk (myself included) will continue to keep their starter in the fridge regardless of the outcome. I'm sure, standard, unaltered flour will work just fine.
Any thoughts on pizza dough formula to apply this?

Actually, I was thinking that baking with the starter(s) would even complicate things further.  Because now we are introducing many other ingredients and variables that have their own flavors that can further complicate testing.  Also, participants may not be able to agree on what formula is best suited for the test.  

I was just going to be tasting the raw starter and making a judgment from there.  I know not everyone is im the habit of tasting raw starters or dough, but it is relatively harmless and an easy test for varying levels of acidity and sourness.   I think it would be easier and more accurate to taste the raw active starter than compared to a baked product.  

Just to be clear, I am only taking a small bit of the active starter and tasting it with the tip of my tongue.  I am not actually eating spoonfuls of this stuff.  You can really get a good idea of the acidity and flavor of a starter this way.  Also be careful not to put the stir back into the starter after its been in your mouth.  We don't want to introduce enzymes and bacteria into the test starter.

If there is a perceived takeover, then baking with the new starter would be a good confirmation step.

[JimmyG]

Craig,
So it appears that the onset of gelatinization begins around 130F (Tgi) and finishes near 190F (Tge) and water inhibits gelatinization to some extent.  That is pretty interesting and explains a lot of my semolina hole structure at 72% hydration, thanks for the resource!

[Jackie Tran]

That's why I only wanted to use sterilized flour for one side of the test. That way if the non-sterilized fed culture changed and the other didn't, we'd have a pretty good indication of the source of the invading flora.

CL

So let's see if we can standardize the test after all.  Let me know if you would rather keep the initial test simple to start with and just use plain unsterilized  flour for the first leg of the test.  If it proves true that we can create a takeover, then we can retest with either just cooked flour or both.  Or we can go full force and do both at the same time.  As it is, I may not have the extra time in the morning before work to wait for the cooked flour to cool, although I think the starter can be added as long as the cooked dough temp is below 100f.  So it may only require a 10min wait.  

Also is a 8-10% seed okay or do you think We should up that?   I am still planning on keeping the hydration of the starter around 70%, but a 50/50 mixture (100% hydration starter) works for me as well.  A 10% seed with a 100% hydration dough will probably be active in 6-8hrs?  Im guessing here.  

Let me know.  Crap it's 12:30am here and I need sleep.  Thanks for all the feedback gentlemen.

[JimmyG]

So let's see if we can standardize the test after all...

In my experience the simpler the design the better the outcome. You can always expand in the future but that is my two sense. 10% seed culture I would think would be  more than sufficient.  

[bakeshack]

I would suggest to keep things more manageable, those members who found that they can maintain unique starters do the room temp test to see if one of their starters will change compared to their original starter after 2 weeks or so and vice versa.  Since we are already convinced that one of these scenarios are true (based on our personal experience), then we should do the opposite and see what will happen.  In this way, we already have a baseline starter to compare the test with.  I keep my starter at room temp (fed once a day) so I will do the refrigerated starter test and see what will happen.  My experience is similar to Brian S.

Maybe it will help if we can share the maintenance conditions and schedule that we are currently doing now with our starters so the other group can replicate the process.  My starter is always kept at room temp (65-75F).  I feed it (10-15% seed amount) everyday at 12mn but you can always pick a time that works in your schedule. 

Marlon

[Jackie Tran]

Good idea Marlon.  The more manageable and simple the test and routine, the more ppl we can get to particpate and the more likely members will see the test out. Marlon, your starter is 50/50 (half water half flour)?  Also what flour do use for feeding with, is it bleached?

Do you taste the raw starter before feeding, and if so what does it taste like?  Can you describe the starter prior to feeding it?  Does it still show some activity?

[bakeshack]

Chau, I use unbleached bread flour for feeding and it's kept at 100% HD.  During feeding, the starter still has some activity at the surface although it has already started declining, maybe halfway down.  I taste it once in a while but not on a regular basis.  It has sour notes to it but you can still taste the flour.  The aroma is more to the level of smelling wine instead of smelling alcohol.  When I am making bread, I feed it again around 12nn for use a few hours after. 

Marlon

[widespreadpizza]

Hey guys,  may have been mentioned,  but would it be possible to sterilize the flour using extremely low temps,  maybe using dry ice or liquid nitrogen,  therefore not messing with the starch/sugar conversion etc.  Just a thought.