Keeving is a old-world cider technique that has largely been forgotten, but is still done by some traditional cider makers in the UK and France. Simply put keeving releases natural pectin into the apple juice which then coagulates, removing much of the nutrients from the juice. As the yeast ferments the keeved juice, it uses the remaining nutrients, but runs out before it can ferment all of the sugar. Traditionally, this has been done to create a naturally sweet cider. For more information on the process, read this.
When I learned about this process and how it works, I thought about how lambic wort is brewed to have a lot of complex sugars that Saccharomyces can't eat, which leaves a portion of the sugars for the Brettanomyces. I began to wonder if Brett would survive in a nutrient poor environment after the Saccharo died out. So the purpose of this experiment is to see what will happen if I pitch lambic yeast into keeved cider.
However, this turned out to be a very difficult and laborious process. I started with nearly 4 bushels (160lbs) of apples. They had to be sent through a mill and the pulp left to sit for 24 hours (to release the pectin). The next day we pressed the pulp, but our efficiency was about half that of a commercial cider press (and 10 times the work). Leidel's Orchard actually spoke with a couple commercial presses keeving, but they were unable to do this process without a major rework of their set up. I was hoping to get 8+ gallons, so I borrowed a friend's 12 gallon glass carboy to use as a keeving tank. I only ended up with 6 gallons.
Then the keeving process starts. The first step is to allow the pectin to coagulate in the cider. Some modern additives help this process, but it is still a bit of an art. The carboy was stored in my refrigerator for 10 days where it is cold enough to stall fermentation until the coagulated pectin gel has formed.
|Most of the gel that formed fell to the bottom and is sitting on top of the sediment|
|Separation of cider and pectin gel.|
|Pectin gel pushed to the top by CO2 bubbles.|
|5 gallons of keeved cider with lambic blend yeast added.|