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.