What am I missing about wort aeration?

[shopkins1994]

Hi Everyone. I had a question about why to aerate wort. From what I have gathered, one aerates wort so that when you pitch the yeast there is oxygen in the wort which allows the yeast to reproduce. Without the oxygen the yeast can't reproduce. My understanding is that once the oxygen is consumed, the yeast stop reproducing and start fermenting. Now, my question is, why not just add more yeast in the beginning instead of aerating your wort? If the goal is to have the yeast reproduce so that there is more yeast, why not just add more yeast when you pitch? That seems more of a sure thing opposed to hoping you get enough reproduction to get the right yeast amount.

Any help you can give is appreciated.

Sam

 

[flars]

This will help you out.
http://www.howtobrew.com/section1/chapter6.html

 

[Qhrumphf]

Hi Everyone. I had a question about why to aerate wort. From what I have gathered, one aerates wort so that when you pitch the yeast there is oxygen in the wort which allows the yeast to reproduce. Without the oxygen the yeast can't reproduce. My understanding is that once the oxygen is consumed, the yeast stop reproducing and start fermenting. Now, my question is, why not just add more yeast in the beginning instead of aerating your wort? If the goal is to have the yeast reproduce so that there is more yeast, why not just add more yeast when you pitch? That seems more of a sure thing opposed to hoping you get enough reproduction to get the right yeast amount.

Any help you can give is appreciated.

Sam

Biology is never so black and white. Yeast reproduction is a key facet of what lends character to beer. The yeast do more than just eat sugars. And if you take the reproductive cycles out, you start impacting that character.

Pitching more yeast to reduce reproduction will suppress esters. If you want to brew beers with very little yeast character, that's something to consider. However, for brewing beers that have a large impact from the yeast (Belgian styles, English styles, Hefeweizens, etc), that's a very bad plan. And if you go to an extreme level even on a very clean beer (even in something like a Pilsner), you can produce a dull and lifeless beer that won't taste right at all.

There's debate and experimentation around this subject (albeit not much), for sure. But at the same time, the mechanics of fermentation and yeast behavior have been very heavily studied for a very long time, and unless you're looking for something specific (in the name of science or a very specific flavor impact), there's really no use ducking centuries of research. If it was a really good idea to do it that way as standard practice, it would have already been established as such.

 

[GuldTuborg]

There are some styles (strong Scotch ales) where it's traditional to pitch huge amounts of yeast into under- or unaerated worts. However, as has been said, this has impacts beyond how many yest cells you end up with in your beer.

Pitching rates and oxygenation routines are just two more variables to consider when brewing. It's tough to nail down exactly what difference they will make in any given situation, given the number of other variables, but as far as I know there isn't any good way to remove them as variables in the equation, so to speak.