Oxygenating Wort

[Richard Deeble]

I'm currently trying to upgrade some of my brewing practices so I can brew decent lagers and higher gravity brews. I've worked out that while my current "shake the fermenter" routine is fine for lower gravity ales, it probably isn't ideal for beers that put greater strain on the yeast like lagers.

According to research by wyeast, the maximum level of O2 you can get from air (either an aquirium pump or simply shaking) is 8ppm. Apparently yeast do best with between 10-15ppm. This leaves me looking for a cheap and easy way of using pure 02. I'm probably intending to just pump it into the headspace of my fermenter then shake it into solution (apparently this is quicker than using an airstone).

Some American homebrewers seem to use disposable oxygen tanks which can be readily purchased from hardware stores over there. However, I have only found one place in NZ that sells these and it is in Auckland and they only do mainfreight shipping due to the danger of transporting oxygen. I could no doubt hire another cylinder from BOC, but that seems expensive and a waste considering I'm only going to use it for a minute or 2 every couple of weeks....

So...what are your strategies for oxygenating wort? What do you think is the cheapest way of getting it in New Zealand?

[Smiffy]

My reading suggests that yeast only needs oxygen to reproduce, not to produce alcohol, so if you make a good starter, the rest of the wort shouldn't need any oxygen. Only theory though.

[JR]

There is a brew strong episode on the topic at thebrewingnetwork.com.  You should find that usefull.  Another idea is to shake the fermentor up at pitching, then give it another shake up at 12 hours to re-oxygenate the wort. (that idea may come from that podcast, I cant remember where I got it.) 

There is a rival beer radio program out there too that has a show on oxygenation where they measure dissolved oxygen from a variety of methods and give the results, just cant remember what its called.  Found the link to it from this site somewhere.

[MrC]

I would look at other options before going for pure O2. It seems like overkill for home brewing. If you think yeast health/growth is your problem you could try these:

- Add Wyeast nutrient to your boil. Yeast seem to perform a lot better with this.

- Shake the fermenter for longer. For my big beers I rock the fermenter for 2 x 5 min ( 2 because I need a rest in the middle). It creates a huge long standing head on the wort.

- Add some olive oil. It provides fatty acids that would normally get created during the yeast's aerobic growth phase. Just a toothpick dipped on olive oil and then dipped in the kettle is enough for a 20L brew.

- Pitch the right amount of yeast. MrMalty is a good place to start for pitching rates.

While the wort contains oxygen the yeast will mainly be reproducing. When the oxygen is all used up the yeast start producing alcohol. Both are important parts of the fermentation process and both contribute to the beer's character. You need to get just the right amount of both.

[Richard Deeble]

I generally add nutrient. According to wyeast, you only need 45 seconds of shaking to get to 8ppm and you can't go beyond that-I used to shake for a heap of time too. I generally watch my pitching rate pretty carefully too. Olive oil is a decent suggestion I guess based on that research paper.

I'm generally fine when brewing ales and I get good clean ferments with decent attenuation. Its brewing lagers and very high gravity beers which by my own reading and listening need more oxygen, unless you decided overpitch and negate the growth phase. This is probably the best solution if I want to brew a lage without pure O2, but it possibly means that beer will be too clean because the yeast has not grown enough to produce esters etc.. I feel like if I want to brew something like a bock, which is expensive enough in terms of time and ingredients, I want it to do it really well.

[MrC]

Are you noticing problems in your beers to make you think about all this? Are you getting poor attenuation? Off flavours? If so how would you describe them?

[Richard Deeble]

No problems with my low gravity beers at all. If I get over 1.070 I feel like my ferments could be slightly cleaner, even though I ferment with temp control and make sure my pitching rate is ok. I guess most of what I have been thinking about is based on what I have read and listened to (Jamil etc.) in relation to lager brewing and correct yeast management. If I just keep brewing ales below 1.080 and don't try and brew super clean lagers then I'm happy to continue doing what I am doing. I just feel I could make "better" beer If I could get above 8ppm

[Chad Keven]

i got a cheap whisk, cut the end off and put it in my cordless drill and found it aerated well (after pitching) it foams up a bit but it only needs a minute or so. it worked fine, although i havnt done it in the last few brews and cant really tell if it made any difference, i think if you have a really healthy starter the brew is gonna go crazy anyway