Beer batches consistently turning sour

The Homebrew Forum

Help Support The Homebrew Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Can you not avoid the kegs altogether, maybe divert a part of a batch from your PV direct to demi-johns or similar, and thence to bottling? And see how those go?
Yes I’m definitely going to follow the split batch approach this next time. So I’ll split in to a couple of fermenter options and then split those in to kegs and bottles. Whilst I’m feeling it’s more something to do with my kegs and leaning towards oxygen, I still can’t say for certain either way. So I’m just going to rule out as many possibilities for the cause as I can and then use this split approach to further rule out more general avenues. If I find an issue in one particular area or process I can either dig further into or avoid a particular thing going forward. It will hopefully be a fairly interesting experiment that will have helped me learn a lot by the end of it, but even more hopefully I’ll end up with some beer I can drink 😄
I had an issue with beer going sour in the keg once. It turned out to be a keg issue.
I thought I had cleaned out and sterilised my keg properly but as I too brew NEIPS ect with leaf hops it turned out I had some leaf hops caught in the dispensing valve of the keg which infected the whole brew. The solution was to fully dismantle the keg and its fittings for cleaning and to use a bounce filter to prevent hop debris getting into the keg in future.
Some interesting reading there! I’m going to try cultivating some samples just out of my own curiosity. But I’ll definitely go to town on cleaning the kegs. I always take them to bits and the last time I boiled the posts, lids, prv and rubber seals but perhaps I need to pay more attention to the dip tubes and kegs themselves. I’ve got a keg spray ball on my brewtools kettle that I use with the enzybrew cleaner from Murphy’s but perhaps I need a bit more manual scrubbing inside and maybe something stronger.

I tend to use pellet hops although the last brew I used leaf hops but only in the kettle, I do a fairly good job at keeping any hops and trub out of the fermenter during transfer. In the past I’ve used a boiled sanitised hop bag to filter heavily kettle hopped beer as I transfer and haven’t had issues on those beers with souring. The last beer I used stainless steel hop containers with the leaf hops in the kettle so as not to block the pump so didn’t need to worry about straining.
Last edited:
Just an update I've done my next brew tried to keep things simplish in terms of recipe and process but I have adopted a LODO approach for this brew to eliminate hotside oxidation.

I've done a Citra Smash pale ale, made with Marris Otter Extra Pale and Verdant Ale yeast.

I used a LODO approach to brewing this beer, boiling my strike and sparge water first before cooling to strike temperature as quickly as possible with my chiller.
I also added 100mg/l of potassium metabisulphite to my mash water and 15mg/l to my sparge water.
I used phosphoric acid this time instead of lactic acid and maintained 5.3ph in my mash and 65c +/- 1c through out.
WhatsApp Image 2022-01-10 at 11.22.23 PM (1).jpeg
WhatsApp Image 2022-01-10 at 11.22.24 PM.jpeg

I used a pipe lay on the grain whilst mashing to minimise disolved oxygen whilst mashing and stirred carefully without disturbing the surface too much.
WhatsApp Image 2022-01-10 at 11.22.23 PM.jpeg

Pre sparge gravity of 1.070
WhatsApp Image 2022-01-10 at 11.22.22 PM.jpeg

I sparged using my sparge manifold which will have got some oxygen pickup but within an accepted tollerence.
WhatsApp Image 2022-01-10 at 11.22.21 PM.jpeg
WhatsApp Image 2022-01-10 at 11.22.20 PM (3).jpeg

I adjusted my pre-boil wort with an additional 5ml to finish with 5.3ph.
WhatsApp Image 2022-01-10 at 11.22.20 PM (1).jpeg

I boiled for an hour adding 30g Citra at first wort and 120g for a 20min hopstand at 76c, reached my target of 1.056 also confirmed with a hydrometer
WhatsApp Image 2022-01-10 at 11.22.20 PM (2).jpeg

I split the batch with 40l going in my SS brewtech Chronical and 17l going in a glass Carboy.
WhatsApp Image 2022-01-10 at 11.22.19 PM.jpeg
WhatsApp Image 2022-01-10 at 11.22.18 PM.jpeg

Both were sterilised with fresh boiling hot starsan for 30mins and all valves were boiled in starsan for 30minutes prior to this. The carboy was rinsed with boiling water before filing.
The transfer pipes and blow-off pipes / bubble valve were also treated with boiling water and fresh starsan.
The chronical fermenter is temerature controlled at 20c and the carboy is in a fairly ambient airing cupboard around 18-20c
Yeast was pitched evenly dry and the wort was thoroughly aerated beforehand.
Gloves and fresh sanitiser used through out.

I will leave both of these 2 weeks now before cold crashing and transferring to a mix of kegs and bottles. All will be treated to my boil cleaning cycle.

This is my recipe: Brewfather

I'll let you know how it goes...
Last edited:
It sounds like a lot of good suggestions a so far . I was thinking contaminated kegs or chiller but that was covered. You mentioned rinsing the FV with boiling water. I was going to ask if you mill the malt near the FV as this can cause a Lacto infection from microbes on the malt. If there is dust inside or around the outside that might be problematic. That's all I can think of right now.
A note on purging kegs, I use Iodine sanitizer instead of Star-san to keep the foam and oxygen down. I use Star-san everywhere else besides the kegs.
Hope you find the problem and good luck.
Ok so here is my update....

I left the beer a little longer that initially planned, partly as I could see a little activity with the yeast bubbling on for a week extra on the ss brewtech chronical (3 weeks in total) and partly as I was busy (I ended up leaving the carboy about 6 weeks). I didn't cold crash and kegged/bottled warm.

I filled 12x 500ml bottles from chronical and 1.5 kegs. The kegs got a full strip down but most importantly I dismantled what turned out to be fiddley poppets in the keg posts (mine are the ones with the little 3 prong things that clip inside the posts) and I also stripped the disconnects (which I've done before) removing all the o-rings and springs and reassembling.

Kegs purged with fresh water, 1/2 tsp k-meta to strip and co2 from the water and then starsan at typical strength and then purged with fresh co2.

I force carbed at high pressure on the chronical batch reaching a decent level after 2-3 days. The bottles were conditioned for 3 weeks using the 500ml carbonation drops and swing top bottle, which were sanitised and co2 purged prior to filling.

The carboy I left a fair while as I was busy and wasn't looking forward to racking it in all honesty. I filled 13 bottles and half a keg or so with the same method. I managed to get a syphon going with a disconnect on the liquid out post of the keg and just left the prv open and let gravity do it's thing which worked suprisingly well.

So the chronical kegs...

First tasting day (2-3 after kegging) the beer was a little sweet, a little hazy (which I was expecting), good apricot flavour from the yeast (verdant), some malt flavour and not much hop flavour (which was expected as there wasn't much added). I was please with the bitterness and sweetness balanace, but the beer lacked a good dry hop so the sweetness was a little cloying.

About day 6 the bitterness picked up in the beer from the early bittering hops I think this was just the flavour devloping probably the interplay with the carbonic acid from the co2 and the bitterness from the hops. This however improved the flavour of the beer dramatically and it tasted far more balanced. I dropped the pressure down to serving around 9 psi.

Over the next 2-3 weeks the beer remained pretty stable in flavour, but then I noticed the sweetness dip and the bitterness seemed more pronouced. Still drinkable and no sourness. The beer was clearing up a little as yeast settled and again the lack of dry hops wasn't going to really give a stable haze. I wondered if the yeast dropping out of suspension maybe was changing the flavour slightly.

The flavour then seemed different over the next couple of weeks almost every time I tasted it, I thought I started noticing a little sourness and bitterness as before a couple of times, but then other times that subsided. I tried to taste with clear pallate before eating or drinking anything else and after both savoury, salty and sweet foods, but didn't seem to draw any parrallels.

Today I'm drinking the same beer, and it tastes absolutely fine nice balanced flavour, the apricot from the yeast is shining through nicely and the sweetness is back to the levels of day 6.

My thoughts so far was that I over carbonated the beer initially and perhaps this has been the bitter sour flavour I've percieved with the carbonic acid interacting with the bitterness of the hops. I also wondered about what I ate or drank before was affecting my perception of the flavour but I tried many things and today I even ate a cookie before which I thought might really make it seem more bitter or sour, but it didn't. So there is definately something going on I don't understand with how the flavour develops in the keg and I suspect this is related to CO2.

On to the chronicals bottles, again the same cloying sweetness in a bottle I tried after a week of conditioning, flavour similar, more malt, more apricot and more gentle carbonation, similar haze to the keg.

After 3 weeks conditioning the carbonation was spot on and the head was much creamier than the keg, the flavour slightly sweeter than the keg but the bitterness had balanced out nicely the same as the kegs on day 6 on to week 3.

So on to the carboy, I've kegged this beer the same, I gave it an initial blast of co2 at 3 bar for about 12 hours, and then I came around to my thoughts around over carbonation so I dropped the pressure down to about 9 psi and left for a couple of weeks. I've just tasted it today and the flavour is fantastic, much more balanced and the head is creamier like the bottle conditioned beer.

I've not tried the carboy bottles as they need another week or so conditioning, but they are likely the same as the others.

I did find a little scudge in one of the keg posts when I was dismantling and scrubbing things. This wasn't visible until I completely dismantled the poppets and even then it was hardly noticable and as I said had been boiled.

I'm still undecided if this was an infection or if it was over carbonation, I think the warming of the beer with a high level of carbonic acid in it would potentially make it seem like its becoming more sour/bitter in the glass and would certainly explain some of the things I've noticed this time. There is still something I don't understand about flavour development or flip-flopping between bitter and sweet and back again within the keg and the timespans these occur over or the impact of co2 on flavour and how that develops or changes (Any links or recommended reading would be much appreciated around this subject).

I will see how things develop with the carboys keg, but overall I've got drinkable beer which I'm very happy with, but I'm still not confident with what the changes in flavour are caused by and how to predict or understand these better, which makes me a little apprehensive about trying a big hop heavy beer again just yet.

Ps the beer ended about 5.9%
Last edited:
Can anyone else taste the sourness?

Yes my better half has been regularly tasting for me but I also have a few beery neighbours that have tasted too for me. I've just finished the keg from the carboy, and that was perfect all the way down. The gentler, slower carbonation seemed to make a big difference to the flavour, really clear citra and apricot from the yeast. Also I finished the second fermenter keg the other day and as it got a little more yeast churned up in suspension from my guestimating how much was left, the flavour was much more rounded as well.

I'll brew again this weekend so hopefully I can take what's worked from this experiment and see if I can refine things further to hone in on the more desirable flavours I've achieved along the way. Maybe I'll do a split batch again with a heavy dry hop in one and see how it affects the bitterness.



Latest posts