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Cube Sour™

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Officially launching the ‘Cube Sour™’ as a new technique.

Overview: 

Make a clean lacto sour beer, using something similar to a kettle sour method. 

Process: 

1. Brew, mash out, cool to temp to suit Lacto strain, sour in a plastic HDPE cube over 24 hrs

2. Bring to boil after this, add hops etc. chill, ferment as normal, then a enjoy crisp, tart Berliner Weisse on a hot summers day. Maybe two.. 

 

Details: 

This is actually easier than a normal brew 'evening' for me as it was split over two evenings where I didn't have to get up after everyone was asleep to finish the brew, like I usually do with a normal batch of ‘non sour’ beer for an evening brew. 

Just did a brief google, someone asked the question if you could cube sour back in 2017 on AHB https://aussiehomebrewer.com/threads/kettle-sour-in-a-no-chill-cube.96248/ 

No-one really provided an answer back then. Apart from that couln’t find much evidence of this being a ‘thing’.

I just winged it with the ‘cube sour’ recently, to make my first sour beer, a Strawberry Berliner Weisse.

I figured that using a cube it was the best way for me to run an anerobic sour at elevated temps for 24 to 48 hours, rather than a kettle sour, where I would have to leave my HERMS mash tun sitting in the garage on recirc for 24 hrs, and risk isovaleric or butyric acid formation due to oxidation.

My jerry can shaped HDPE cube fits in my Westinghouse 130L fridge only bar fridges with ease, and my 25W  reptile heater cable (used to warm the chamber during winter) I have found can keep the internals at 40C plus quite happily. 

I guess it would be so easy to sour by simply adding 88% lactic or using a heap of acid malt, and may make not much difference to the taste of these clean lacto type sours like modern versions/interpretations of Berliner Weisse and Gose, I don't know however as I haven’t done a comparison.

I do know that the first one that I made using this process tastes as good (I think) as the Wayward Sourpuss, albeit with strawberries rather than their raspberries. 

According to the guys on the Sour Hour, they say it’s quite a bit harder to get strawberries tasting good in these beers when compared to raspberries and many other berries, so this process must be ok.

So for the Cube Sour, I simply ran the AG brew as normal, (basic low gravity recipe for a Berliner Weisse, 2kg Plis malt, 1kg wheat malt, 500g unmalted wheat, 200g acid malt, targeting a pre-boil gravity of around 1.038 at a shade over 80% mash efficiency for 25 litres or so.

Mashed out at 78, didn't boil, then, as recommended for a kettle sour, added a calculated 13ml 88% lactic acid to adjust ph down from 5.2ph to to 4.5ph to prevent nasties like botulism or any other contaminates taking hold in a giant sugar laced liquid filled vessel at 42c for 24hrs..

Racked to cube at that temp (assuming that despite losing some heat when racking to cube, it would remain above temps required to pasteurise the cube), then squeezed out air then sealed, then chilled the cube in the backyard swimming pool to 40 something degrees Celsius, (took about 20 mins in the pool)

Then opened cube and pitched in 1 litre lacto starter made the day before. Squeezed out air again then sealed, then in brewfridge set to 42c. Next evening measured PH, was approx. 3.25.

The Lacto starter was made with a tablespoon of my home made greek style yoghurt, by mixing 100gm DME with 1L water, in easiyo yoghurt maker so sitting at 40 something C.

Another way to do this would be to add the yoghurt directly to the cube, I have since tried this and it had only reached 3.6ph after 24hrs, so needed 48 to hit the approx 3.3 target PH

So now for the boil, easy job to pour that cube into the kettle topped up with some water that would boil off during the boil, (in my case 2.5 litres for a 60 min boil) added a few hops, in this case enough for approx. 4IBU, 15 grams Hersbrucker 3.9aa at 15 mins and 15 grams Saaz 3.2aa at 5 mins.

Boiling means you lock in that PH and kill the lacto, meaning you can use your usual fermenting and packaging equipment with no fear of contamination, unlike mixed fermentation sours.

Racked back to cube after boil, chilled in pool, pitched k97 Saflager German ale yeast (which is perfect for this, doesn’t mind a bit of acid..)

Fermented as normal and then added 3kg of strawberry puree at end of primary fermentation, let those ferment out, bottled, enjoyed.

I should add that if the wort is not sterile or becomes contaminated in the process by something in addition to the lacto, something that can that generate CO2, like wild yeast etc, that can also survive at PH4.5 or below, and above 40C, then the cube could burst, making an enormous mess and putting you on thin ice with SWMBO.

Because the cube is HDPE plastic, it is not a risk to anyone if it did blow, just would mean a lost batch and a lot of cleaning, maybe a few tears..

I was concerned about this and checked the headspace size a couple of times with my Brewcam, an IR webcan that I sometimes put inside the fridges, and there was almost zero gas produced with the lacto souring over that 18 hrs or so. BTW The wort lost approx. 1.5 gravity points, I assume the Lactobacilus consumed this to create the acid.

If you try this and the cube starts to pressurise, I would vent it and go ahead and boil it, and adjust it with lactic acid instead or simply turn it into a standard weisse beer.

 

I’ve now made two batches like this and the 2nd one is “Cube Souring™” right now, I didn’t make a lacto starter this time, instead just a tablespoon of live yoghurt, as mentioned above. No gas is being produced even after 36 hours, headspace size is completely stable.

Other sources of lacto can be Yakult, IBS capsules, or you can mix them up. At the recent home brew conference in Melbourne, there were some pro brewers from NZ I believe talking about using a couple of types of yogurt plus yakult for their kettle sours for added complexity.

In my photo here, you can see the jerrycan shaped HDPE in the LHS fridge with my 2nd Cube Sour going on. Sitting happily at 42C with the reptile heat cord inside. This one is destined to be a Nectarine Berliner Weisse.

The RHS fridge has a Golden Sour fermenting in primary with Wildflower bottle dregs that I grew up in a starter.

So can I claim to have launched the Cube Sour? I doubt it, but happy to promote the technique and answer questions if I can with my limited two batch experience!

 

 

CubeSour.png

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The first time I tasted a sour beer, I thought, awful, not for me, what's the fuss about these.. 

Then the second was about the same, the third I thought, maybe there's something to these things, before long I was very interested in the styles. 

Check out the Wayward Raspberry Berliner Weisse, formerly known as 'Sour Puss' to taste something like the above. These are a good starting point as not funky like the barrel aged stuff, many people find trying sour and funk at the same time a little too much for the taste buds and never try the stuff again.. 

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Quote


Recipe: Passion Sour 213

Style: Berliner Weisse
TYPE: All Grain

Recipe Specifications
--------------------------
Boil Size: 30.00 L
Post Boil Volume: 26.69 L
Batch Size (fermenter): 23.00 L   
Bottling Volume: 21.60 L
Estimated OG: 1.041 SG
Estimated Color: 4.8 EBC
Estimated IBU: 7.6 IBUs
Brewhouse Efficiency: 75.00 %
Est Mash Efficiency: 85.4 %
Boil Time: 60 Minutes

Ingredients:
------------
Amt              Name                                             Type          #          %/IBU         Volume        
2.00 kg          Pilsner (Weyermann) (3.3 EBC)                    Grain         1          50.0 %        1.30 L        
2.00 kg          Wheat Malt (Barrett Burston) (3.0 EBC)           Grain         2          50.0 %        1.30 L        
5.00 g           Super Pride [13.90 %] - Boil 60.0 min            Hop           3          7.6 IBUs      -             
750mL passionfruit post fermentation
-------------------------------------------------------------------------------------

that was mine. i cubed hot, the next day threw in 4 IBS capsules. left for 4 days. poured back into kettle, boiled, cubed then fermented a few days later. the lacto is murdered by the boil, the cube sorted by the hot wort. the beer was a cracker.

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Great stuff, I was hoping to run a passionfruit one as well, coming into season very soon!

Ben did you read about this idea or did it just occur to you? 

My first one was back in mid october, but I think you ran this one before that. 

In any case yeah these are turning out so clean and impressive, I think the sealed souring in the cube makes a big difference. 

Long live the Cube Sour! I just ran the boil tonight for my nectarine one, right on target at 3.3ph after two days with one mildly heaped tablespoon of live yoghurt, no starter. 

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13 hours ago, headmaster said:

Ben did you read about this idea or did it just occur to you? 

based on my first couple of kettle sours being unpredictable i wanted a way to keep the bugs to a known - ie a sealed environment - so it was just a thought process.

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Thought about doing this last weekend but went with kettle souring. Using a cube sounds far better. At least this last one doesn't smell like vomit this time 🙂

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Yeah that's the risk, with O2 exposure getting isovaleric or butyric acid formation. That's why people put cling film on the surface of the wort in the kettle, which to me sounds a bit hit and miss. Sealing it up in a cube and squeezing the air out will be a lot more predictable.  Isovaleric and Butyric are the worst two off flavours in beer I think, baby chuck, diaper, vomit, etc. Not great. 

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I have tasted butyric acid in a beer (a Dainton Berliner Weisse) and it was disgusting. It also led to me vomiting for a couple of hours.

It is best to avoid that 😉

Edited by Hairy
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Nice ground work, Headmaster!  Been thinking about trying some kettle sours...  this looks a much better method especially if you are familiar with no-chill to begin with.

Looking forward to having a stab at it. Is there a commercial yoghurt you'd recommend?  Or particular probiotic culture?

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Hi Room full of mirrors,

The people from my brewclub who have tried the capsules have had no issues, one mate used 10 I think and it soured in 15 hours or so, I think he adjusted to ph 4.5 beforehand. 

I guess I would prefer to not have Irritable Bowel Syndrome capsules in the provenance of my beer, when explaining to people how I made  it, it sounds better to talk about greek yoghurt, etc. 

I make heaps of yoghurt at home in one of those easiyo things, just using a couple of teaspoons of the last batch, some UHT milk and half a cup of milk powder. You mix that, while boiling the kettle, pour in the hot water in the easiyo and put the 1L container in there, As easy as making a cup of tea, and you get 1L of natural yoghurt for about $1.10. You need the UHT as the heat treatment is required to denature the milk proteins to get the yoghurt to set. If you use fresh milk you need to heat it up and cool it down and mess about etc. 

Anyway I digress..

I like the Farmers Union greek yoghurt. 

I was not at the home brew conference in melbourne recently but there was a talk all about this from a pro brewer from NZ I believe, that is making some great kettle soured beers. 

They said they use two types of yoghurt and yakult in theirs. 

Different types of lacto like different temps. The yoghurt varieties usually contain some of  Lactobacillus, delbrueckii,. bulgaricus, acidophilus, brevis and helveticus

All I know about mine is it likes up to 48c. 

That temp will kill lactbacillus plantarum, a commonly used one for brewing and sold in some LHBS. It likes closer to 30C, This is easier for craft breweries to use as they don't need to heat many thousands of litres up so much to get it to work. 

 

 

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Okay, now I'm looking into homemade yoghurt!!!

I rode the wave of no-chilling beers when it was introduced and also BIAB back in its pioneering phase,  I reckon you are on to a winner with this Cube Souring technique.  We are lucky to have among us innovators and risk-takers that progress and promote the craft of brewing.  Thanks for your great work and congratulations on your technique.

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Just cube soured a small pilot batch of gose on the weekend. Souring went off without a hitch. The rest was a bit of a debacle, but that had nothing to do with the souring process...

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The yoghurt is great ROOMFULLOFMIRRORS, highly recommended. I can post some more detail in the 'Everything Else' section if you like. 

And I certainly can't claim to have given birth to this Cube Sour, but I am already a big fan. My Nectarine Berliner Weisse has just finished fermenting out about 3.5kg of puree that I made on saturday, they had become quite ripe and sweet with a week on the bench.

So chopped them up, removed the seeds, pasteurised the fruit up to about 75c, then blended with the stick blender, cooling and racking the mostly attenuated Weisse on top of the puree. 

Last time with the Strawberries, I just dumped in the puree in primary and it went nuts due to the amount of yeast and was a coopers FV lid lifter, almost making a giant mess. Had to cool it down to 10C to slow it down using Safale k97 german ale yeast, and whip the krausen down with a whisk. 

I pasteurised the fruit because I wanted this beer to remain clean, at the possible expense of some of the fine aromas. If I were putting fruit into a mixed fermentation wild yeast and bacteria beer, like I have in the other fridge, I could choose to skip that and possibly gain added complexity from the wild yeasts on the fruit. 

 

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WOBBLY74, 

Good one, with the cube sour, hope it works out well. I've never made a Gose, but it's on the short list as now I know I can sour beer reliably with this method. 

Let us know how it goes there

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On 11/27/2018 at 4:30 PM, Ben 10 said:

 the beer was a cracker.

How much passion fruit flavour comes through?

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for me it was perfect, good taste but didn't get in the way of the beer sourness

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10 hours ago, headmaster said:

...I can post some more detail in the 'Everything Else' section if you like... 

 

Yes please!  I'd love to give it a go ...yoghurt and cube souring!  Christmas holidays project 😉

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Bringing this thread back to life because I'm going to brew a Berliner while I'm on holidays. Perfect summer beer to compliment a saison and XPA!

will seek out some IBS capsules to start with. My pH meter is on the way and I have lactic acid to bring the pH down in the cube before pitching the capsules.

 

V exciting! Thanks @headmasterand @Ben 10 for sharing your processes

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Great stuff Jools. The ph meters can be a tad tricky to master.  Make sure to calibrate every time you use it and store the sensor in ph 4 buffer or even better ph meter storage solution. 

I've never had the latter,  quite expensive,  must get hold of some one day..  I have two,  one has digital calibration the other calibrated with a trim pot. 

The digital one can be calibrated with multiple buffers so you can calibrate with ph4 then 6.86 or the other way around, depending on your expected measurement range.  For eg I will cal 6.86 then 4 if I am measuring something nearer to 4 than 7 like mash ph or sour beer wort. If doing the backyard pool,  I cal 4 then 6.86 because the expected reading is low 7s.  

 

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Looks like tomorrow is cube sour time! I'm home with the kids, no preschool, no commitments so I want to put a berliner down, transfer to cube and let it cool.  Straight after I want to start the mash on another brew, a Citra saison. First double AG brew day for me and means I can keep the cube at approx 32C for the lacto plantarum for a couple of days, boil on Sunday and that will free up my fridge to pitch the Citra saison. Very excited!!!

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