How did you make that sour beer?

The majority of sour beer brewed in Ireland at the minute has been brewed by a technique called kettle-souring. There are exceptions like The White Hag, Otterbank and more recently Land & Labour. Kettle souring enables a brewery to get a sour beer on the market in the same time-frame it takes to make a conventionally brewed beer and therefore leads to a quick turnaround and no beer sitting in tanks and wooden barrels for months and years on end taking up space in which another beer could be made. It is also cleaner and a risk-free way of making a sour beer due to the lactobacillus being boiled off before going into the fermenter.

The purpose of this post is not to belittle the kettle souring technique, quite the contrary as I use it myself along with another souring technique that can turn out sour beer pretty quickly and will describe here. It is however frowned upon by many of the brewers who prefer to age beer with microbes to obtain a more complex sour. The reason I want to explain it a little more is because lately, as the Irish craft beer market grows and people start to see sour beer on the shelf, I get a lot more people asking me how I make a beer sour or what is in a sour beer. The following technique is one of about four that can be used for a quick sour beer. Kettle sour, souring in fermenter, sour mashing and long term souring with pediocussus+lactobacillus+Brettanomyces/saccharomyces. I’ll be using the second of these.

Purpose: To make a sour beer, bottled and conditioned fully within 4 weeks using some pilsner malt I won for a previous sour beer in the Midlands Beer Club! Shameless plug.

60% Pils malt (from my medal winning previous kettle sour!)

40% Belgian Wheat malt

No hops at all used in the kettle

50g Citra dry-hopping for final 5 days

50g El Dorado dry-hopping for final 5 days

WYEAST 3724 Saison yeast

OG=1.042 FG=1.004 IBU=0

60 minute boil. 25 litres into the fermenter. Measured ABV 4.8%

The idea was to create a sour beer without kettle souring and without having to wait the guts of a year.

Process: Mash as usual, in this case 67c then boil for an hour and cooled to 42c then transfer to the fermenter.

First time ever using WYEAST so smacked the pack without making a starter and it was bursting and ready to go into the 42c wort which I would let cool naturally to 38c. I picked this yeast because it can ferment at temperatures as high as 38c which is also the optimal range for the lactobacillus I use. It’s Wyeast equivalent of the Dupont strain and is also famous for stalling it’s fermentation at 1.030. This can be alleviated by keeping minimal pressure on the fermenter by leaving the lid loose or using tin foil instead of an air lock but I kept the pressure and wanted the stall as this is where I would be adding Brettanomyces in the form of All The Bretts from Omega yeast labs to finish the beer off in conjunction with the 3724 to give me a Brett Sour. My thinking was the Brett would grab those dry-hops and enhance the fruity flavor profile they can throw off and also give me an initially not so complex sour that will evolve due to the Brett into something more complex with time.


42.8 temp control is hard maintain. 38c with a heat-belt is fine…..just about.

When I pitched the yeast I also pitched 10 tabs of BioKult straight into the fermenter. No pre-acidification was performed so starting pH was around 5. It’s good practice to make a 1litre starter with the BioKult tabs but I went for the straight pitch this time. No hops were used in the boil as an IBU level over 10 can prevent the lactobacillus going to work.

I checked the pH 4 days later when the fermentation was in its stall phase and it had dropped down to 3.46 which is slightly about real sour beer territory but still exhibiting the tartness I’m after. This is where I added the Brett and monitored the pH daily but it seemed happy in the 3.46 range possibly due to letting the temperature slide down to 24c(Lacto is happier at 40ish Celsius).

After 9 days my FG hit 1.004 and remained there until bottling. The pH was stable at 3.46 but I added the dry hops here which would prevent any further drop in pH. Dry hopping also raised the pH up to 3.52.


Always check your sour beers with a pH meter. Even commercial ones for a surprise.

The hops were in for 5 days then I bottled all of it to saison carbonation levels and conditioned them for two weeks.

Tasting Notes:


What’s a coolship? More on that later. Check out that seating arrangement though.

Orange. The beer looks orange, smells orange and tastes of orange with an array of other citrus fruits thanks to the Brett enhancing the Citra and El Dorado. It has a nice tartness that lingers. No perceptible Brett initially but there is an additional complexity that I don’t usually find in kettle soured beers that will hopefully develop further with time. It pours a rich and full head that dissipates over the course of a few minutes.

This was my first time using this process and if I have to brew another quick turnaround sour beer this will be my go-to technique.

Turns out it’s the finest damn sour beer I’ve ever made and not a fruit in sight to optimize flavor.

Hope this technique inspires someone else to give it a whirl.

I promised to give some advice on foraging for wild yeast and that post is coming soon!

Thanks for reading.


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