I I know that after a while, say 3 weeks or so, that the yeast will break down which will affect the beer.
You don't really "know" that, you've just heard some old wive's tale about it. Big difference.
People have successfully had their beer in primary for upwards of 6 months with no issues....
You will find that many of us leave our beers in primary for 3-4 weeks (or more) and only secondary if we are adding fruit or oak, or to dry hop (though many of us dry hop in primary now as well)....and we have found our beer vastly improved by letting the beer stay in contact with the yeast.
There's been a big shift in brewing consciousness in the last few years where many of us believe that yeast is a good thing, and besides just fermenting the beer, that they are fastidious creatures who go back and clean up any by products created by themselves during fermentation, which may lead to off flavors.
Rather than the yeast being the cause of off flavors, it is now looked at by many of us, that they will if left alone actually remove those off flavors, and make for clearer and cleaner tasting beers.
Even John Palmer talks about this in How To Bew;
How To Brew said:
Leaving an ale beer in the primary fermentor for a total of 2-3 weeks (instead of just the one week most canned kits recommend), will provide time for the conditioning reactions and improve the beer. This extra time will also let more sediment settle out before bottling, resulting in a clearer beer and easier pouring. And, three weeks in the primary fermentor is usually not enough time for off-flavors to occur.
John Palmer
As a final note on this subject, I should mention that by brewing with healthy yeast in a well-prepared wort, many experienced brewers, myself included, have been able to leave a beer in the primary fermenter for several months without any evidence of autolysis.
People have left it as much as six months. Autolysis is a myth for homebrewers.
Even when Palmer is talking about it, he's talking about it in terms of LAGERS not ales. Most people get so freaked out about in reading Palmer, that they don't notice it is in the Lager chapter, nor do they notice the caveat at the end of the section that I posted above.
I still believe that POSSIBLY autolysis WAS a concern to homebrewers 20-30 years ago, when the yeast came in dry cakes, of dubious heritage and came across from where homebrewing was legalized in the hot cargo holds of ships and may have sat for months in terrible conditioned...In other words was unhealthy to begin with.
And therefore may have crapped out and made for nastiness, (and also was prone to stick fermentation as well.) and tales of it just continued to perpetuate over time, even though yeasts are much more healthy and fresh, and more is understood about them nowaday....people gravitate to the negative and fear and still perpetuate those worries...over and over and over....
And I still maintain that as much as I like Palmer, he contributed to the hysteria.....I mean noone but me seems to notice that that section on the scary autolysis appears in the chapter on
lagering. He is not talking about it with ales...or beers in general..just lagers..because flaws are more perceptable in lagers...since in essence most commercial lagers are tasteless...anything would stand out..
and I think most new brewers have crapped themselves at the mere thought long before the notice the closer to the section I mentioned earlier.
This is where the most up to date brewing wisdom and ideas can be found...In fact a lot of stuff has been started on here, and made it into byo or zymurgy or podcasts...in fact BYO DID a piece on no secondary/long primary, along with the BASIC BREWING PODCAST and even they said that there were no issues/harm with doing it and in some beers it did actually improve the flavor and clarity. And I believe that really WAS influenced by the discussion we have had for the last couple years on here.
and have some questions.
