I have only made and used a leaven once before and I am interested in putting a gap in the process. I started a leaven, foolishly, two days before I went away on a short break of four days. The leaven had been maturing for two days, so I popped it into the coldest part of the fridge then when I returned, because it looked very healthy, I continued feeding it. Effectively, it is now on its fourth day but I want to know if it will be useable in view of the four day break? Also, can a leaven be used, say after three days, if it is fermenting well?
Leavens are remarkably resilient, very high temperatures will kill the yeasts but this is only over 75 centigrade, cold really only slows the rate the yeast multiply, which is essential if you are going away and can't feed them.
I have found it an excellent plan to put the leaven in the fridge as it slows the whole process down, but you will need to be careful to make sure there is enough yeast food, i.e. fresh flour available, otherwise even though the process slows down it will begin to become very sour.
The balance in nurturing your leaven is to ensure the lactobacilli don't become too dominant, this balance is maintained by feeding the yeasts, if the yeast food runs short the yeasts will stop multiplying and the lactobacilli become more active and the acidity will rise, making the leaven sour not sweet.....this balance has to be regulated by you to suit you own preference...
You can dry the levain in a warm oven and then store it as a dried crispy product, which when rehydrated comes back to life!!
Have fun, and let me know how you get on.