A few weeks ago I got some kefir grains and I've been really enjoying making my own kefir. The smooth sourness and wonderful flavors made me wonder about brewing with kefir grains so I launched the grand experiment. I'm brewing a small batch tonight for part 1 of the experiment. The grain bill is classic lambic, nothing too crazy. I'm going to split the batch in two and start one with US-05 then finish with kefir grains. The second half gets all kefir grain fermentation. I'm hoping for something lambic like. Batch two will be a similar experiment with a milk stout grain bill.
1lb Belgian pilsen malt
12oz US torrified red wheat
2oz Belgian aromatic
0.2oz aged Saaz
I did a 75 minute BIAB mash at about 152-154°F for a pre-boil gravity of 1.046. (84.5% efficiency...pretty standard for a small batch BIAB for me). I boiled for 60 minutes with the hops in for the full time (and a pinch of irish moss for the last 10 minutes or so). I had some hops in the freezer from quite some time ago (at least a year). It was mostly Saaz but probably had a little of something else mixed in. Chilled in the sink to about 70°F then split to two growlers. OG is 1.054. Pitched 1g of US-05 in one container and 0.5oz of rinsed kefir grains in the other.
I checked this morning and the yeast half is fermenting nicely. The kefir portion has pushed the water through the airlock with an occasional bubble so it seems to be doing ok although it's starting out slowly.
On Monday evening the yeast half had slowed significantly so I took a gravity reading. At 1.021 it seemed mostly finished (40% unmalted wheat and a low mash temp leaves lots of unfermentables). I racked to a secondary and pitched 0.5oz of lightly washed kefir grains. The kefir only half is fermenting fairly well now. Not a full on yeast fermentation but a couple of bubbles a second.
The kefir half had slowed and cleared by Wednesday evening. The gravity is at 1.022 which is essentially the same as the yeast half. There's not any sourness but I didn't compare the two. The estimated FG for the batch is 1.013 so there may be room to drop still but it might need brett to get the rest of the way. I'll give them a few more days and see if it's steady then do a comparison. I'm thinking I might need to move on to experiment 2, a milk stout. Maybe the addition of lactose will give the kefir something more to chew on.