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Gose Beer Sour Kettle Method

So this was my second attempt at a sour beer. The first I did in a Burco with an STC-1000 temp controller. It didn’t go so well as the probe was stuck in the mash and this meant that the boiler kept on overheating the wort. It would have been much better if I’d put the temp probe near to the bottom of the boiler as I’d have got a much more accurate reading and subsequently better control.

So I went crazy and got myself a Braumeister for my birthday. The first beer was a simple pale, and the second was this.

The method is basically this:

  1. Make a starter (I used acidulated malt grains and cider – a lot of people use DME in water and crystal – I think I’ll try that next time)
  2. Grow the starter at 40-45C. I’d read that 45C was better as it inhibits the heterofermentive lacto and other nasties like Clostridium that produce “baby vomit” smells)
  3. When the starter is ready (3 days? Should smell nice and fruity and tart) mash the beer.
  4. Drop the finished mash down to 45C and remove the grains. I actually left mine in there for the lacto fermentation.
  5. Bring the pH down to about 4.4 with some lactic acid (I brought mine down too far due to me not reading the pH strip properly). This will make the mash a happier place for the lacto and less hospitable for other bacteria.
  6. Innoculate with the starter.
  7. Flush with CO2.
  8. Hold 45C for as long as it takes for the pH to drop to 3.4-3.6. Test daily. Mine took a week and I had to chuck in some extra crystal as I’d lost confidence that the starter was doing anything.
  9. Bring up to the boil and run the hopping schedule.
  10. Ferment as normal with yeast.

The advantage over traditional Berliner Weisse methods that just pitch in a mix of lacto/yeast is that you have complete control over the acidity of the beer. You are also able to increase the hop bitterness levels – which you can’t do on a regular Weisse/Gose due to the hop oils inhibiting the lacto.

The fermented beer came out not too remarkable to be honest. It was nicely tart but on the nose was lacking in complexity. It smelt a bit like a simple cider. So I ended up doing a couple of things that completely transformed the beer. Firstly I threw in some Orval dregs for that brett complexity. After a couple of days (see pic below) the typical brett pellicles started popping up, and after about two weeks, the brett funky smell came through. It was lovely and almost savoury. A few weeks later, I hit upon the idea of adding some grapefruit. I took three (for a 20 litre batch) and shaved the zest and juiced them, then heated the zest up in the juice to Pasteurize and also extract a bit more of those oils nice and quickly – making sure I didn’t heat it up too much and lose those lovely delicate aromas.

The grapefruit went in and immediately it transformed the beer. In the beginning it overwhelmed the brett smell a bit but now it has balanced out and this really is a great beer. I’m bloody happy with it – it’s one of my best so far.

Recipe Details

Batch Size Boil Time IBU SRM Est. OG Est. FG ABV
19 L 60 min 14.476408 3.242660 1.038 sg 1.038 sg 0.000000

Style Details

Name Cat. OG Range FG Range IBU SRM Carb ABV
Gueuze 17 E 1.04 - 1.06 1.01 - 1.015 0 - 10 3 - 7 0 - 0 0 - 0 %

Fermentables

Name Amount %
UK Wheat Malt 2 kg 49.14
UK Pale Ale Malt 1 kg 24.57
German Pilsner Malt 1 kg 24.57
German Sauer(Acid) Malt 0.07 kg 1.72

Hops

Name Amount Time Use Form Alpha %
US Sterling 20 g 60 min Boil Leaf 7

Miscs

Name Amount Time Use Type
Salt 14 g 60 min Boil Other
Coriander Seed 14 g 60 min Boil Other

Mash

Step Temperature Time
Rest at 66°C 60 min
Raise to and Mash out at 0°C 0 min

Fermentation

Step Time Temperature
Aging 0 days 0°C

Notes

Want to do a 64.5C mash for 1hr then 74C mash out for 15 mins. Drop to 45C (add cold water to reduce/top up?) and pitch in the Lacto starter.

Lacto starter is 400ml of apple juice with small handful of acidulated malt thrown in held at 48.8C for 2 days. Will thrown in another small handful of the acid malt and some crystal to the sour kettle process to innoculate further. Will keep at 45-46 to inhibit nasty bugs and heterofermentative lacto. Will aim for the sour mash to bring pH down to 4.5 before kettle souring. 36 hours should be enough to bring it down to pH 3.6. May be better not to taste due to risky business going on.

Purge BM with CO2 and seal the lid with tape due to risk of clostridium bacteria.