My first experiment with sour beers was a kettle soured beer with fruit. It proved to be very popular and resulted in another 2 batches being made this past summer.
Kettle souring is a “safe” technique in that it uses cultured lactic acid bacteria in the wort before the boil. The boil kills the bacteria and there is no worry about them running away (making an excessively sour beer) or contaminating the rest of your brewing gear.
This beer is based on the Northern Brewer Funktional Fruit Sour. Without repeating the recipe, here are the highlights from Batch 1
Day 1 (friday night) Boil the malt only wort for 5 min and then cool to 80-85F. Leave it in the brew kettle. Add the lactobacillus culture and cover. Heat must be applied. My Spike 10 gal Brew Kettle can be set up with a side mount thermo well into which the thermo probe is inserted and the heater wrapped around. Initial pH was 6.5
Day 2 make up the starter. 1.3 l water, 3/4 DME boil and cover the flask with aluminum foil. Chill to 68f. Add the yeast. So far, there have been 3 batches T-58, BE-134 and EC1138 I like the T58 the best for this one.
Day 3 (Monday eve) The pH has dropped to 3.53 – nice and tart. Now We continue with the brew. Do this per the recipe including primary fermentation. 2/3 tsp Fermax was added per batch .
10-14 days later transfer to secondary SG 1.017
Add the fruit. All of the fruit had been frozen, then heated to a boil, and mashed with a “motor boat” style stick mixer to break it up. Each 5 gal batch required :
- 2lbs frozen Blueberries,
- 1lb mixed frozen fruit (Raspberries, strawberries and blackberries),
- 12 oz frozen blackberries
- 1lb frozen cranberries
The blueberries all came from my garden. While I grow the others, including high bush cranberries, I do not get enough for brewing so I have to resort to store bought frozen.
I still do not have the perfect technique for managing the berry pulp in the fermenter. The first batch I just dumped it in. This required twice filtering to keep the keg from plugging with bits of pulp. The second and 3rd batches I placed in fine mesh bags and then in the fermenter but they were too “floaty” trapping the C02. I tried venting them with 1/2″ pvc pipe but this was not great either. They still floated. I shook the fermenter daily to attempt to keep things mixed up and prevent mold growth (if the fruit on top dries out it is susceptible to mold).
Batch 1 5 days primary, 14 days secondary OG 1.054, FG1.02
Batches 2&3 Additional 1.5 lbs golden light DME per batch above the kit fermentables.
10 days primary, 35 days secondary Added EC1118 yeast i batch 3 in secondary Batch 2 OG 1.070 FG 1.007, Batch 3 OG1.073 FG 1.009
Transferring the first batch to the keg. 2 more filtering passes were required.
As you can see the beer is a brilliant PINK.
The FG ranged form 1.007 to 1.009 across the batches. This is a family favorite. All of the ladies love it, especially those that don’t care for the IPAs and Imperial Stouts that I do otherwise. The girls have requested that I keep it on hand for all family gatherings and summer boating.
Note that some articles suggest removing the precipitate from the kettle souring step. The lactobacillus layer on the bottom of the kettle can scorch and create a burnt rubber flavor. Tip for my next batch.