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Ideal feeding moment for starter, when?

NoNeed's picture

Ideal feeding moment for starter, when?

Hi all,

Normally I feed my culture once every 24 hours or so.

But what is the prefect moment to feed? Is that when the culture starts to cave in? I am talking about a culture here that's still developing. It's not maure yet. It did smell like acetone after not feeding it for 6 days days (I waited for bubbles to resume feeding).

Thanks, still learning a lot....

Davey1's picture

Many people (not me) wait till it rises and then falls. If you're staying a starter wait till it falls. Enjoy! 

tpassin's picture

It's not a complete question.  When is a good time (or the perfect time) to feed a culture ... for what purpose?

- Maintaining it;
- Using it to leaven dough;
- Making it more or less acidic;
- Using it to seed a build of levain.
- Changing the balance between yeast and bacteria;
- Fitting into a demanding schedule;
- Etc.


NoNeed's picture

What is the right moment to feed when you're starting a culture?

Basically I am in the process of changing the balance from bacteria towards yeast, as I understand it. 

I recently take bubbles or not as the guide to feed or not. So I resumed feeding when, "no bubbles" changed to "quite some bubbles" + acetone smell because these signs showed a clear shift in the kind of activity of the culture. This was after not feeding for six days without any bubbles. 

I fed and discarded for two days and got rid of the acetone smell, but the multiplying is still only 1/5 of the volume per 24 hours.

What feeding approach is good from here? And what signs should be watched most? 

  • Feed it a little bit each day?
  • Feed it every other day?
  • Go by thinness or smell?
  • Discard with each feeding or only when very acidic or acetoney?
  • Better under or over feed?

Sorry for the many questions.! I am here to really really understand the best I can. 

I am getting into it more and more... 

tpassin's picture

I fed and discarded for two days

There are several variables in play here:

- How long between feedings, or how did you choose when to feed?
- The feeding ratio.  For example, 1:2:2 (old starter:water:flour, by weight).
- The behavior of the starter between feedings.
- The fermentation temperature, but I'm going to assume you have a more-or-less normal room temperature, say between 70 and 75 deg F. Lower temperatures will slow things down, higher will speed them up.

If you are not getting much rising action, that suggests either very little yeast or bad growing conditions for the yeast.

Bubbles on the top aren't always to best indicator of activity.  Sometimes the top can be fairly smooth but you can see masses of bubbles through the sides of the container.  That's perfectly fine.  If you can't see through the sides of your container, get one where you can.  In this situation the top may not show bubbles yet still have heaved upwards by gas production, which also shows up as those bubbles below the surface.

It's helpful to think in terms of dilution of the yeast and bacteria (I'll say LAB though there can be many species).  Let's say you have 10g of old starter and you add 100g each of flour and water.  You have just diluted the concentration of the yeast and LAB by a factor of 10.  The yeast will take a long time to process all that flour, and multiply enough to get back up to the original concentration.  You have also reduced the acidity, which will recover over time as well.

Suppose you feed the culture again before it has returned to those original concentrations?  You will have diluted the mixture even more than the first time, so the culture is starting from a lower concentration than originally.  IOW, feeding  too soon can have the result of continually driving down the yeast concentration.  You don't want that.  Luckily you don't have to worry about being exact here, but overfeeding and feeding too often will tend to reduce the concentration of active yeast.  

This is why there is an emphasis on feeding a culture when it is fairly active.  In that phase, the yeast is not doing much multiplying so its concentration is fairly high and stable.  The longer you wait after this time, the more acidic the starter will get, and at some point the yeast will run out of food and tend to become inactive. If you are trying to change the yeast-LAB ratio in favor of yeast, you don't want that either.

Stirring or kneading the starter will tend to restore more growth.  So if  you want even more yeast, when it has gotten pretty active, or even started to subside, stir it up and watch it become active again.

If you feed using a low ratio, like 1:2:2, you won't be changing the concentrations much, so you won't be changing the starter's character much.  You also won't be making it much less acidic, so you may find over time and feeding that it gets more and more acidic, which may not be what you want.

To sum up, if you want to favor yeast over LAB, feed at higher ratios, say 1:5:5 or 1:7:7, feed when the starter is quite active or at least as active as it gets, and perhaps also stir it as it develops.

Again, none of these items are critical, so don't worry that you won't get it right.  They are only generalities and you will learn better from your own experience with your own starter.

tpassin's picture

If you want to reduce the LAB in your starter, you could salt the starter heavily.  I did this, as an experiment, with a starter I kept on the countertop and fed as needed or convenient.  I kept increasing the salt content.  2% of flour weight doesn't do much except slow down the fermentation a little (and it reduces protein degradation, which why I'm doing it these days).  But stepping up to 4% and 6%, I found that after several weeks of refreshment with 6% salt, the LAB dwindled away to nearly nothing, judging by the flavor of the bread it made. The bread just didn't have much taste any more. 

TMac's picture

...that 2% salt added to starter reduces protein degradation. I might play with that, especially as you said you do that regularly. First time I've heard of adding salt to the starter. What concrete benefits to the end result have you observed (if any). It was my thought that salt had more effect on yeast than LAB, but what do I know...

tpassin's picture

One change has been that my 100% hydration starter, refreshed just before bedtime, used to be on the thin side 8 hours later.  Now it's not, and if I stir up the starter it springs back to vigorous life instead of being done for.  I'm using bread flour instead of AP, but that alone didn't have the effect.

It's hard to be sure but the bread I've been making is not worse and probably better.  I've been making the same kind - the one I posted about using 80% WW atta flour - and now I'm getting the best loaves ever.  The loaves have been getting fabulous oven spring and the best flavor to date.  Here's an example:

Years ago I tried using just a pinch of salt because I read that the SFBI said it only took 1/10 of the usual amount of salt to counteract protein degradation.  But it never seemed to do anything I could notice.  The 2% - and actually I've moved to 1% day in and day out - really seems to make a positive difference.

Another difference I've noticed is that after sitting for 8, 10, even 12 hours after refresh, the starter doesn't smell acrid or acidic, which it would have done before I started adding the salt.  The pH is about where you would expect, but the smell is different.

To be complete, I should say that this starter consists of 10 - 20% of that atta flour, the rest bread flour, and I have been throwing in a few grams of rye bran because I have a lot of extra.  Refreshment has been around 1:5:5.  But I started with the salt before I began adding the rye bran, and still got good results.

TMac's picture

Good explanation and it seems like something worth playing with. I'll give it a try! Thanks!

Davey1's picture

If baking on a schedule - feed about enough to last till the next bake - if - and it's a big if - the starter is ready. If not baking on some kind of schedule disregard. Enjoy! 

NoNeed's picture

That sure helps. Good explanation... I noticed that stirring can be a good check to tell if there was any food left in the culture that facilitates some rising again - if it does rise again you know you can leave it without food for some longer.

Finetuning the lactobacillus is not an issue here. I just want the starter to be as active (yeast) as possible. Don't want to make it more complicated than that atm.

I do work with a 3 stage fermentation recipe though. Especially "my" 3 stage 70% rye bread with raisins is my favorite...

I am getting there, knowledge wise :)

tpassin's picture

I noticed that stirring can be a good check to tell if there was any food left in the culture

Stirring can also introduce more air into the culture, and more air (with its oxygen) allows yeast to multiply more.  I'm not sure how effective this factor is, but it's in the right direction.

Abe's picture

The starter feed/levain build for Tartine's Country Bread Sourdough. They do the levain build when it comes to Starter %, Hydration and Flours used but they allow it to fully mature and use when ripe. However if one looks at the instructions it's fermented at cool temps and only left to expand by 20% before it used. This produces a milder sourdough... On the website itself, and in many others making this bread, they simply say mix and use when mature which is most understood as peaked. But here's a snippet from the book itself...

So as you can see it is a big feed, fermented at 65F and only left to expand by about 20%. Also, by bakers percentages, the levain is 20% - so quite a high amount. The resulting bread should be quite mild. I don't think Chad aims for a very tangy loaf. He has recently taken to making it more mild I believe.


EDIT: Just read a comment of your further down and you aren't looking to make bread yet. You are trying to get your starter off the ground. So please ignore my comment above as it won't really apply to your starter yet. 

Acetone = hungry. Feed more but wait till there are signs of fermentation before feeding again. Right now don't think about gearing your starter for one thing or another. You are  trying to get it to a stage where it supports the yeast and bacteria for a starter, you wish to keep it fed but at the same time you don't wish to upset the balance. 

So I would think increase the amount of food but still wait enough time till you see activity before feeding again. If it takes 24 to 36 hours then fine. 

What you could do is when feeding again take some of the discard and try a side experiment. With the discard, and in a new jar, try a 1:5:5 feed - e.g. 10g discard + 50g water + 50g flour (a big for this early stage but it's just a side experiment) and don't feed it again for however long till it springs to life.