Here is one of the examples of making yeast in the 18th century where they prepare a batch of flour with some boiled hops, then a small batch of barm is added which turns into a large batch of leaven. And note the saving of a piece of “old dough” for the next baking.
The process of making yeast as practised at Edinburgh is as follows: Take two ounces of hops boil them for an hour in two gallons of water and boiling hot scald eight or ten pounds of flour and stir it very well into a paste. Do this about eleven in the forenoon. Let it stand till fix o clock in the evening then add about a quart of yeast to forward the fermentation and mix it well together. Next morning add about as much more flour and water sufficient to make it into dough and in the afternoon it will be sit for setting spunge and baking. Reserve always a piece of the old dough to mix with the new batch instead of the yeast which is necessary only the first time to hasten the process The above quantity of hops will suffice for an hundred and twenty quartern loaves.
From the “The Seaman’s Guide” John Cochrane 1797
Savoring the Past 
Your videos and now the Blog are great learning tools and I absolutely love them. I check my subscriptions every day to both.
My question today is about the saving leaven you talked about in your video and very much related to today’s blog post. You showed how to preserve leaven by salting a chunk of dough, then reconstituting and straining out the yeast.
This seems like a great way to preserve for the long term, but clumsy for the short term. Taking this concept from your video, I made a 1:1 slurry of water and flour and then threw in a pinch of fresh bread dough (about a teaspoon) and threw into the jar of slurry. I had a culture within hours. The simplicity and ease of this makes me think this would be the every day way of carrying leaven over for the average person. I have no historical documentation for this and is only an experiment based on what you have taught so far.
I am still in the experimental stage playing with this and have only made one loaf so far. Playing with the amount of fresh batch leaven (vrs. an aged sourdough), I still need to figure out the amount of time needed for rise and the amount of fresh batch leaven to use.
Just thought I would share what you have inspired and how it is working.
Thanks again, I really appreciate your historical teachings.
Dean,
In the videos it can be very hard to get all you want accross without making an hour long boring episode. You are talking about this “old dough” idea perfectly. Just like at the end of this blog article, it talks about saving back a piece of dough to use later. In this context they did not mean to preserve to dough for any length of time but use it probably the next day. Now you went ahead and made a slurry but you don’t have to go that far. Just take out the old dough from yesterday and plop it right into today’s flour, salt and water. Knead away until it is smooth and set it aside to rise. It is not as quick as instant yeast but in time. Possibly over night your bread will be ready to bake, but don’t forget to set aside a piece of dough for tomorrow.
Thank you.
John your doing an awesome job, I and my family enjoy your informative videos .
Kevin,
Thank you for your kind compliments. I do want to point out that this is not a one man show. While I do some research and write the occasional episode, Kevin C. does a lot of the research and most of the writing as well as the directing and camera work and Aaron B. does the sound and all the computer grunt work to turn out the episodes. And I can’t for get all our other great employees that slave away churning out orders while I do this stuff.
Jon