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Feeding ferment (Bertinet method) - how much to take out/replenish?

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ajkessel's picture
ajkessel

Feeding ferment (Bertinet method) - how much to take out/replenish?

I'm doing the best I can to follow Richard Bertinet's sourdough method set out in "Crust." One thing I'm quite confused about is the volume of ferment. I bake about once per week. Bertinet suggests you should have 800g ferment; take out 400g for two loaves, and then refresh with an equal mass of water (i.e., 400g) and twice the mass of white bread flour (i.e., 800g). So after taking out the 400g and feeding the ferment, I have 1200g of mixture. If I kept this pattern up, the ferment would just keep getting larger and larger.


Is there an undocumented assumption that you will be throwing out 400g every week in addition to the 400g that you take out to bake with? Or is the mass supposed to magically decrease? Or are Bertinet's measurements just wrong in the book? I'm wondering if I'm missing something obvious here.


Thanks in advance for any tips/suggestions/advice!

dmsnyder's picture
dmsnyder

Yes. The assumption is that you will discard most of your "ferment" and just save enough to feed back up to 800 g. I don't have "Crust" (the book), but I suspect you are misinterpreting Bertinet's instructions.


Look for his instructions for feeding the ferment. It sounds like he wants you to make it at 50% hydration. The missing piece is the amount of ferment to retain and feed. My best guess is that, by "equal mass of water," he means equal to the retained ferment. Thus, the feeding formula would be:


800 g = x g + y g + 2y g, where x = ferment, y = water, and x = y.


This calculates to 200 g ferment + 200 g water + 400 g flour = 800 g of refreshed ferment.


I hope this helps.


David

ajkessel's picture
ajkessel

Thanks, I'll try that! The directions are a little confusing -- I've written Bertinet separately directly based on the other forum comment. The directions say (page 52):



So, to the 400g of ferment you have kept back..., add 400g of water and 800g of white bread flour.



And then in the actual recipe of the bread, it calls for 400g of ferment. So if you follow that literally, I think you'll always end up with extra ferment.

Richard Bertinet's picture
Richard Bertinet

Hi - if you can email us at queries@bertinet.com Richard will gladly answer your query in person.


Best wishes


The team @ The Bertinet Kitchen, Bath, UK

spriolo's picture
spriolo

You're supposed to get rid of ferment?  I have a 55 Gallon drum of it in my living room! (( Just kidding I don't )).


Although, from what I can see your ferment must be HUGE.  1200g addition is bigger than most loaves of bread!  How many loaves and what shape does the formula call for, and how much are you throwing out?


A second thought.  I've notice that when I quadrupal my Barm I get the best taste and performance from it.  So if I have 200g held back and I add 300g of water and 300g of flour (I keep mine at 100% hydration) those wild yeasts jump for joy and go crazy (end wieght at 800 g).


It make really good sourdough bread when they are so agressive.

ajkessel's picture
ajkessel

 


I add the following to 400g of ferment:


 



  • 90g spelt flour

  • 700g strong white flour

  • 650g water

  • 20g salt


 


I end up with two decent size round loaves. For scale, this is a very large knife:




 

ajkessel's picture
ajkessel

 


I add the following to 400g of ferment:


 



  • 90g spelt flour

  • 700g strong white flour

  • 650g water

  • 20g salt


 


I end up with two decent size round loaves. For scale, this is a very large knife: