Tuesday 23 June 2015

Yeast in your beer

I used to be a fan of yeast in beer. It's not that I no longer am, but that my focus has changed a little. I came into the beer scene whilst running a pub that majored in real ale. Back then the idea of craft keg was barely a thing in the UK. Cask was king, and of course still remains so in many pubs and ares, even if stunning keg beers are really starting to take off in a good and positive way. Cask is unfiltered and generally contains at least some live yeast. Cask remains stubbornly a sign of quality beer for many, despite the major disadvantage of variability of actual dispense quality.

Bottled beers are, in reality, a different matter altogether. The Belgians seem to do bottle conditioning very well indeed. Some British breweries can do a good job. In reality though, it is an extremely difficult thing to do well, needing a knowledge of the residue fermentables in the beer to be packaged, the current carbonation level and a yeast cell count and viability. Equally there may need to be oxygen present if secondary fermentation is to occur, but not too much, else the beer might stale early.

We have bottle conditioned in the past. We intended to produce entirely bottle conditioned beer originally, as we felt this was the "right" thing to do. We still occasionally play with the technique. What we have found is that the consistency of the finished beer is nowhere near as reliable and consistent as when we simply bottle with carbonation that is picked up in tank.

As a bit of a background, our bottling filler is a counter pressure filler. What this means is that to operate correctly there must be balance between the pre-pressurisation of the bottle and the head pressure in the filler bowl. Failure to get this right messes up the operation of the filler valves and can cause fobing of the beer and so incorrect fill. It just doesn't work right if no pressurising gas is applied.

The problem with this is deciding whether to use CO2, nitrogen or air as the counter pressure gas. If using CO2 with bottle conditioning it can be the case that there is insufficient oxygen dissolved in the beer and therefore there is slow and unsatisfactory secondary fermentation. Using air at pressure might over-oxygenate the beer, causing premature staling. There isn't a correct answer, but one solution used is to ensure minimum residual fermentable sugars, by ensuring complete fermentation, carbonating to a satisfactory level, possibly even chill filtering, or centrifuging and then re-seeding with enough yeast just to give an illusion of bottle conditioning. There will be a tiny amount of secondary, but in reality the only thing this does is mops up stray oxygen, although there is a strong argument for saying this is a good thing.

We used to do this faux bottle conditioning, as do quite a few breweries that have beer in the Good Bottled Beer Guide. We probably could have continued to do this, and so maintained our listing, but we recently decided that this wasn't what was best for our stunning beer.

At the end of the day, a business has to do what the people who make up the customer base really wants the business to do. When we put yeast in our beer we got more complaints about the beer than I was happy about. Gushing bottles, flat beer, beer with bits in it and other failures that are clouded by the questions of whether it is in fact faulty beer, or just consumers not understanding how bottle conditioned beer might behave.

I think the people want great beer, consistently and without bits. We have changed now to a process that drops the beer bright in tank, carbonates in tank and then we put through a rough (nominal 5 micron) filter just for security. There may well be traces of yeast get through, but we do not guarantee a cell count. What we are looking for is minimal secondary fermentation in bottle, as the carbonation levels are exactly as we want them at bottling. The double pre-evac bottling system reduces oxygen in the bottle to an absolute minimum ensuring long shelf life.

The relatively rough filtering ensures that all those stunning hop characteristics we've worked hard to put into the beer don't get stripped out again by a stupidly tight 0.45 micron filtration system often employed for bottling.

And it seems what we are doing now is exactly what the people want. We're getting much love for our beer on twitter etc as it rolls out into Morrisons and Marks and Spencer's. This is helped by the fact that the beer is very fresh. Just today I had to stop typing this post to go load pallets onto the waggon bound for the Morrisons' depot. Some of the beer was still in a tank when I got up this morning. You can't do that with bottle conditioning, and there is now some question in my mind that suggests that really great hop-forward beer degenerates during the secondary fermentation stage. Not so with tank conditioned beer. It's great just as soon as it's bottled.


Stonch said...

Interesting to read of the "faux" bottle conditioning. Back when I used to drink bottled beer (these days if I do it'll likely be a distress purchase and a big brand lager, not anything fancy) I wanted to like bottle conditioned beer and tried lots of it. What I found was that Fullers 1845 and Young's Special London were the only ones that were consistent. I put that down to them just having more experience, but was it that they were using the process you describe, whereas, the inconsistent microbrewery beers I was struggling with were "true" bottle conditioned?

Unknown said...


As I have some knowledge of what Fullers do, you might guess that this is one of the breweries I allude to, but I couldn't possibly comment.

Phil said...

Speaking of supermarkets, I was impressed - well, amazed would be a better word - by the beer range at the farm shop at Tebay services, which includes an extraodinary range of HK beers. I'd never seen Granite, Rhetoric, Queboid, Elixir and Vitesse Noir in the flesh, as it were, & seeing them all together - at a motorway services - was quite something. Wish I'd bought more now.

Unknown said...


Tebay has been and remains the vary best place after the brewery itself to get a wide range of Hardknott beer. The are just brilliant. I was up there a couple of weeks ago and was stunned at how good they are at their food and drink offering. Their meat and cheese counters, artisan bread and just everything is brilliant.

I should do a whole blog post just on them really.

StringersBeer said...

Yeah, BC is hard, which is why a lot don't bother with it (and some shouldn't). I believe Fullers carbonate to something like 2.3 vols and target 2.6 in the bottle? Might be wrong, but that would work out as something like 12% bottle conditioned. Folks with a literal turn of mind might call that kind of thing 88% bullshit. Let's blame CAMRA.

Unknown said...


I know you guys work hard to get your BC right. I think I have some knowledge about your process to be happy to confirm that this is the case.

Personally, I do not think BC is worth the bother, from a commercial point of view.

I think your 88% figure, and it's context, sounds in the right ball-park.

As to the area into which the blame should be apportioned? Again, I couldn't possibly comment.......

StringersBeer said...

I should point out that the Hardknotters do indeed know their BC beer, and have filled a bunch of bottles on their mighty engine for us. Which worked precisely as we calculated they should, i.e. just the same as when done by hand on our tiny filler. For a lot of beers, IMHO, BC adds precisely nothing - apart from some sediment. Many are positively harmed, and only a few are improved.

Curmudgeon said...

I've said in the past that insisting on bottle-conditoning as the only proper way to produce bottled beer is CAMRA's great Emperor's New Clothes. It simply isn't equivalent to cask vs keg.

And many small breweries are encouraged to produce BCAs by just bunging the finished beer straight in the bottle, which produces wildly inconsistent results and does their reputation no favours.

For everyday quaffing beers it's just not worth it.

Ed said...

As far as I've seen the standard procedure for big breweries that do BCAs is to filter, re-seed, prime and partially carbonate.

It is however possible to do decent BCAs, even of modest strength, on v.cheap kit with all the carbonation coming from the secondary fermentation. Just be very careful and don't be tempted to put too long a shelf life on it!

Yvan said...

Exciting post/subject this.

OK - so I moved to the UK in 2006 from a world of almost entirely "sterile" bottles beer. (Some of which was decent.) [Australia]

In the UK at the time bottled beer that was "tasty" was all BC, and that which was a bit naff was "clear" per se.

Basically from my PoV the UK-background is a dichotomy of:

RAIB: has flavour, tastes decent, is lumpy if you're not careful (or is just lumpy regardless)

BOTTLED-KEG: clear, easy to pour, tends to be dull if not quite awful

(I borrow CAMRA terms there, however hilarious)

What has happened since then is folk like BrewDog came along and said: we can bottle our great beer, filtered, but not "sterile filtered" so you have beer that may not be super-consistent but will be super-flavourful.

Subsequently (and probably also previously, but less in-your-facedly) others have done the same. Some filtering, some dropping bright in tank, all counter-pressure-filling AFAIK.)

And these beers stand out for flavour - Magic Rock, Summer Wine, and dare I mention: Hardknott ;) [Much more so of late, and more cleanly, with new yeast and less of a BC thing going on - although I suspect yeast is key here, less BC seems to mean more stable carb level though.]

If folk tell me BC is the only way I point them to the above breweries, and also some of the ultra-trendy "craft can" types.

Yet a stigma is still attached to non-BC, and this is somewhat being perpetuated by "craft" folk who try getting their awesome beer contract bottled. Where it is seemingly always sterile filtered at best, and at worst pasteurised (_too_).

So the "middle ground" that works very well has yet to prove itself. (Non-BC still considered "bad" due to overwhelming evidence in the field and a belief that any haze whatsoever means "BC".)

Meanwhile I spoke to a brewer from Green Flash a while back and he said in the EU they chose to make their beers BC because how how shite the supply chain (cooling) is here. :) So hmmm.... interesting. O2 mopup? Reaction/degradation affects over time versus energy?

The O2 thing is interesting here too. So... O2 is now key to BC? But O2 is bad for finished beer...? I learn a lot from the online beer community, but it does often lead to conundrums. How much O2 in a bottle is "good" - how much is "not enough" - how much is "bad" (oxidation) - and what results in the better product? Is yeast in your bottle a silver bullet for O2/oxidation? (Your PhD research paper due on my desk by December 2017, please... or has someone done this already?)

StringersBeer said...

Making a bottled beer that tastes good fresh isn't so very hard. Come back to it in 6 months, well, who knows. Unless we've done aging trials of course.

Anonymous said...

Although Fullers claim to be raib I have found little or no yeast in their recent beers.I like it that way.

JohnKeeling said...

How much CO2 does secondary fermentation contribute to cask
Bottle conditioning is not just about increasing the CO2

Unknown said...

Indeed, John, I do point out in the text that yeast scavenges oxygen. This is clearly a good thing for extending the life of the beer. We've done tests that do positively prove this to be the case.