In the last few days there was a question in one of the posts about the timing of using a leaven.
(I can't find the exact poster - this forum has got too busy for its own good )
It might have been in relation to Teresa's interesting experiment with different starters - demonstrating different times of 'peak volume'
That got me thinking about a couple of questions that Chembake or Graham or anyone else out there might know the answer to.
When we refresh a starter, what are we aiming to do?
I am going to attempt an answer to my own question
Presumably there are several things happening simultaneously - there is multiplication of organisms (yeast and bacteria), consumption of some of the starches in the flour, production of some of the fragrant by-products of bacterial activity.
When the starter 'peaks' in volume, and then starts to shrink again I assume that the yeast and bacteria have run out of food. Presumably then the rate of multiplication would slow or stall, though I think that the starter would become more sour due to ongoing bacterial activity.
When new flour is introduced (in the form of mixing the dough), new food is added, and the yeast will presumably start to multiply and be active again.
I think that what we are trying to do is to maximise the number of yeast in the starter, as well as produce enough of the 'souring' by products to flavour our bread. But does it matter if you use a starter that is a little 'early' (by which I mean before 'peak'), or 'late' (after peak)?
Say for example that a starter peaks at 12 hours - does it matter if you use it at 8 hours or 10 hours or 14 hours or even 24 hours?
Do you get the best rise with starter 'picked' at peak, or doesn't it make a difference? What about flavour?
cheers
Dom
Replies
Hi Sourdom?.this had been my experience with different starters , If supposing the peak time is 12 hours I can use it at 8-10 hours but I give the dough more fermentation time to compensate for it say around an hour and half to two and the result is just the same if the starter has peaked before used.. It also helps if the dough temperature is about a degree or two higher.
Now if the starter reached its peak more than two hours the level of activity is slower. I also give the dough the same treatment say an extension of bulk fermentation of an hour or more.... But I don?t raise the dough temperature as the dough from overfermented starter tends to be warmer.
Some cultures are robust and even better when it has reached beyond its prime when used.
If you are in a hurry to use the starter say two three hours earlier, I stir the starter briskly for a minutes more than halfway its total fermentation time to aerate and invigorate the critters. And the result is the same if the starter reached its peak before use..
Those really active cultures are more tolerant to under and over fermentation than slower cultures,.
Stirring the starters briskly for a minute is similar to punching a bakers yeast raised dough
A dough whose fermentation time was prolonged due to the youngness or oldness of starters benefit if its knocked down stretched and folded a few times during the dough bulk fermentation.
The bread appears bolder looking and produces better oven spring when baked.
In addition to that even if the dough is full proofed with slashed it tends to have better baking tolerance.
It appears that the knocking down and stretch and folding oxidizes the dough giving it strength.
Thanks Chembake, though I still wonder a little what exactly is going on in the starter.
The amount of rise of a dough must be proportional to
a. the amount of live yeast
b. the amount of yeast food
c. the temperature (determining yeast activity)
d. the presence/absence of inhibitors of yeast activity (fats, salt etc)
So if a 'late' starter (or 'post-peak' starter) has less rising action on a dough (assuming constant temperature, and similar amounts of 'food' in the form of new flour added), does that mean that the yeast numbers have started to drop off after reaching the peak? Are they perhaps starting to make spores? Are there more inhibitors around to yeast activity (perhaps the fall in pH?)?
Another thought. In yeasted breads, there is a definite cost to having too much yeast added to the bread. Although the bread rises faster, the crumb structure and flavour is better if smaller amounts of yeast are used.
Is there a similar phenomenon with sourdough? Could you have too much yeast? Is less better? (I remember Mick did an experiment a while back comparing different proportions of starter in dough, and didn't find any discernible difference between bread with say 30% starter (percentage dry flour weight), and 60% starter)
[quote]
The amount of rise of a dough must be proportional to
a. the amount of live yeast
b. the amount of yeast food
c. the temperature (determining yeast activity)
d. the presence/absence of inhibitors of yeast activity (fats, salt etc
[/quote]
Whether its bakers yeast or levain the principle remains the same but in the levain culture the ratio of the starter to dough is what determines dough performance in terms of fermentation and proofing time. The higher the quantity of starter the more vigorous is the microbial activity.
The other things you mentioned are similar such as temperature , yeast nutrients, and inhibitors.
[quote]
So if a 'late' starter (or 'post-peak' starter) has less rising action on a dough (assuming constant temperature, and similar amounts of 'food' in the form of new flour added), does that mean that the yeast numbers have started to drop off after reaching the peak? Are they perhaps starting to make spores? Are there more inhibitors around to yeast activity (perhaps the fall in pH?)?
[/quote]
There is the time that the microbial growht varies according the active populations; microbes has a lifespan and in time gets weakened and replaced by new ones,. pH is also another determining factor as it tends to slow down microbial growth as the values goes lower.
Spore formation does occur but as its considered a seed it is irrelevant to the microbial activity of the starter. Its this new cells that are young and more active will take the place of the expired ones.
The stirring of starter is one way to introduce air so that the microbes can multiply and grow. The conditions of undisturbed starter fermentation is anerobic and promotes catabolism and gradual destruction of microbial cells , but as its aerated the younger cells are invigorated , food sources are reintroduced from other parts still contains storage areas for food and growth factors. Keep mind that flour is a complex food and is not completely solubilized so not all of the nutrients are released in solutions but some are kept inacccessible to the critters if its undisturbed .The protein and carbohydrate structure has equal propensiity of introducing food sources in forms of sugars and nitrogenous substances, the turning of the dough literally exposes unused areas not in the immediate vicinity of the microbes where the nutrient sources are are already depleted.
[quote]
Another thought. In yeasted breads, there is a definite cost to having too much yeast added to the bread. Although the bread rises faster, the crumb structure and flavour is better if smaller amounts of yeast are used.
[/quote]
I don't think so...bakers never worry about that matter, yeast is cheap and is used only in little amounts, but if compared to levains which are self perpetuating its a different matter
Yes,
Indeed the flavor of bakers yeast raised bread is inversely proportional to the amount of yeast added which corresponds also to slower fermenation activity in the same way as levains do to sourdough.
For a particular bread recipe the smaller yeast used results in better tasting bread
[quote="chembake"]
Whether its bakers yeast or levain the principle remains the same but in the levain culture the ratio of the starter to dough is what determines dough performance in terms of fermentation and proofing time. The higher the quantity of starter the more vigorous is the microbial activity.
[/quote]
I'm afraid I don't have a scientific cell in my body, so, this is from my experience. When I use Ed Woods' recipes...requiring some 4 cups of starters for 2 regular-sized loaves (compared to 1/4 of that for most other recipes)...yes, the dough proves much quicker but I can hardly detect any sourness/flavour in the bread. Not enough time for development, perhaps?
[quote]
For a particular bread recipe the smaller yeast used results in better tasting bread
[/quote]
Yup. Yup. Yup.
[quote]
When I use Ed Woods' recipes...requiring some 4 cups of starters for 2 regular-sized loaves (compared to 1/4 of that for most other recipes)...yes, the dough proves much quicker but I can hardly detect any sourness/flavour in the bread. Not enough time for development, perhaps?
[/quote]
TP ... likely it had something to do with the nature of your starter culture.. It may requires different conditions to promote more acidity....If its contains more homofermentative microbes ( lactic acid forming bacteria)than the heterofermentative ones( acetic and lactic acid forming) then it will be difficult for you to get the required tanginess that you want.
Your microbes may contain more of the L plantarum,L fermentie specie (, L homofermentatvie)than the L. Brevis,L Sanfranciscencis.
So...to pay me back for going Spanish, you're going all Latin on me, huh?
On the sourness issue, my breads can get pucker-up-face sour, especially on long proofs. What I meant above, was the amount of starter was so big that the bread was ready to be baked in just a couple of hours. So, my question a priori (probably) is, the L.homofermentative, didn't get a chance to 'perform'?
[quote]
So...to pay me back for going Spanish, you're going all Latin on me, huh
[/quote]
Dispensa por favor mi amor
I love your way of speaking in Spanistch
It is just I am trying to explain the essence of your problem in precise terms, unfortunately it contains the exact nomenclature of the microbes responsible for such....
[quote]
On the sourness issue, my breads can get pucker-up-face sour, especially on long proofs. What I meant above, was the amount of starter was so big that the bread was ready to be baked in just a couple of hours. So, my question a priori (probably) is, the L.homofermentative, didn't get a chance to 'perform'?
[/quote]
If that is the case then the ratio of the homofermentative and the heterofermentative critters is more of the former and less of the latter.
Hence it results in milder flavor if a large amount of starter is used in relation to the dough ingredients
However if longer fermentation is applied the heterfermentatives being more robust than the homos will take place producing sufficient quantities of acetic acid which is responsible for the distinctive sour taste.,
Again, muchas gracias, mi travieso. This forum is going to make a rocket-scientist-baker out of me yet! 3-2-1.........
Yes TP the first Malaysian a stronaut shot into space with the sourdough leaven?