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Oxygenation of Wort


Otto Von Blotto

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Well I took my SG reading today, the brew has been in the FV for about 72 hours and has a much more vigorous looking krausen on it than I normally get with US-05. It's around 50mm high with huge bubbles on top of it at the moment, as opposed to the usual neat and tidy foam look.

 

Anyway, the reading was around 1.025, so I've raised the temp up to 22C on the controller. I was expecting it to be lower than that even though it's only been in there 3 days. I must remember to calibrate the STC's temp probe before the next batch, I've got a sneaky feeling that it's reading a little higher than the actual temp.

I do have some bottles in the fridge that were bottled two days prior to pitching which sat at 0C until pitching day, so those being in there probably kept the temp lower than desired at the beginning as well. They still feel quite cold now even.

 

It is tasting very promising though, despite the 15 points or so it has left to drop. A bit sweet of course, but that'll go away by the time it hits FG. Smells and tastes very citrusy too, looking forward to this batch!

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Please excuse my naivety and persistent questioning Kelsey, but is this for all grain brewing?

I'm just at basic level, using yeast supplied with the brew can, which I believe is just dropped on top of the wort?

 

I thought I read somewhere that oxygenation wasn't good because of the potential for harmful bacteria or wild yeasts to proliferate, but I guess I've tried to learn too much in a very short amount of time

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It can be used for any type of brewing but I don't think you'd find too many kit or extract brewers injecting pure O2 into their wort.

 

Oxygenation is good at yeast pitching time, but that's about it. The yeast consume the oxygen during their multiplying phase. After that, introducing oxygen isn't good. It's not so much about wild yeasts and bacteria but more about flavour. Oxidation leads or can lead to a variety of off flavours, a couple being wet cardboard or sherry like flavours.

 

They reckon that oxygenation isn't needed with dry yeast (regardless of it being sprinkled onto the wort or re-hydrated in water first) because it already has all the stuff it needs built into it at the lab.

 

I rarely use dry yeast anymore but when I do I make yeast starters with it to harvest from (which turns it into a liquid culture anyway), so I guess it uses up those lab in-built reserves fermenting the starter. In this instance, it's better to oxygenate the wort.

 

 

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It can be used for any type of brewing but I don't think you'd find too many kit or extract brewers injecting pure O2 into their wort.

 

Oxygenation is good at yeast pitching time' date=' but that's about it. The yeast consume the oxygen during their multiplying phase. After that, introducing oxygen isn't good. It's not so much about wild yeasts and bacteria but more about flavour. Oxidation leads or can lead to a variety of off flavours, a couple being wet cardboard or sherry like flavours.

 

They reckon that oxygenation isn't needed with dry yeast (regardless of it being sprinkled onto the wort or re-hydrated in water first) because it already has all the stuff it needs built into it at the lab.

 

I rarely use dry yeast anymore but when I do I make yeast starters with it to harvest from (which turns it into a liquid culture anyway), so I guess it uses up those lab in-built reserves fermenting the starter. In this instance, it's better to oxygenate the wort.

 

[/quote']

 

I appreciate the responses, I have another question for you regarding the yeast, but I already asked it in another thread, and I won't derail this one. I'm not sure which thread it was, I'm not sure how to set my profile up so I get notifications.......

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Hi guys.

 

Something I only recently learned is that the presence of dissolved oxygen in wort is not necessary for yeast growth or survival.

 

If you are pitching yeast at the optimum rate, oxygenating the wort becomes less important, & less of a concern, & can even be detrimental to overall beer flavour with some ale & lager Saccharomyces cerevisiae strains in some cases.

 

An alternative to the oxygenation of wort route is to use a nutrient that contains yeast hulls (dead yeast) in your yeast starter. These same dead yeast are also found in the trub post primary fermentation. This is also why most home brewers experience very good fermentations by re-pitching from slurry from previous brews.

 

In all three cases it is about creating a sufficient volume of yeast with strong cell membranes. If you are not pitching at the optimum rate then cell counts need to be increased, & oxygenating the wort even a little, will help a lot in this department.

 

In the other two cases, you already have an ample amount of yeast cells, so increasing that count again once in the main brew wort becomes unnecessary.

 

I've always had good results on the occasions I've used yeast nutrient in my brewing, but it wasn't until I read some recent literature about yeast cell health & production that I fully understood why.

 

Source: Oxygen's Role in Beer Fermentation

 

Food for thought.

 

Cheers,

 

Lusty.

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Hi guys.

 

Something I only recently learned is that the presence of dissolved oxygen in wort is not necessary for yeast growth or survival.

 

If you are pitching yeast at the optimum rate' date=' oxygenating the wort becomes less important, & less of a concern, & can even be detrimental to overall beer flavour with [b']some[/b] ale & lager Saccharomyces cerevisiae strains in some cases.

 

An alternative to the oxygenation of wort route is to use a nutrient that contains yeast hulls (dead yeast) in your yeast starter. These same dead yeast are also found in the trub post primary fermentation. This is also why most home brewers experience very good fermentations by re-pitching from slurry from previous brews.

 

In all three cases it is about creating a sufficient volume of yeast with strong cell membranes. If you are not pitching at the optimum rate then cell counts need to be increased, & oxygenating the wort even a little, will help a lot in this department.

 

In the other two cases, you already have an ample amount of yeast cells, so increasing that count again once in the main brew wort becomes unnecessary.

 

I've always had good results on the occasions I've used yeast nutrient in my brewing, but it wasn't until I read some recent literature about yeast cell health & production that I fully understood why.

 

Source: Oxygen's Role in Beer Fermentation

 

Food for thought.

 

Cheers,

 

Lusty.

 

I linked to that article already, back in November, 2016, in post #16 of this thread Lusty. tonguewink

 

The article is one reason I am content to stick to my present practice of using sloppy slurry.

 

Gen 1 dry yeast = no supplemental O2 required.

Gen 1 liquid yeast: Shaken Not Stirred starter method = no supplemental O2 required.

 

Subsequent generations: sloppy slurry = no supplemental O2 required.

 

The way I see it, supplemental O2 is only necessary if you are using liquid yeast and a stir plate for Gen 1, or if you are removing dead yeast from slurry by washing / rinsing for subsequent generations, and possibly if you are saving from starters made on a stir plate as Kelsey does, although maybe not even then. I don't think he was having major problems before he started using pure oxygen.

 

Cheers,

 

Christina.

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I linked to that article already' date=' back in November, 2016, in post #16 of this thread Lusty. [img']tongue[/img] wink

Soz I missed that one, as I hadn't really been following this thread. I did remember it existed so rather than starting a new thread, I went looking for it. innocent

The article is one reason I am content to stick to my present practice of using sloppy slurry.

 

Gen 1 dry yeast = no supplemental O2 required.

Gen 1 liquid yeast: Shaken Not Stirred starter method = no supplemental O2 required.

These are both reliant on the gravity you are pitching into' date=' along with the temperature you plan to ferment at as to whether good levels of dissolved O² would be advantageous in terms of assisting yeast cell growth.

Subsequent generations: sloppy slurry = no supplemental O2 required.

Less so in this case as there should be an abundance of yeast here provided it wasn't used on a high gravity brew. Making sure you collect enough slurry is probably the only thing you need to be pragmatic about.

...and possibly if you are saving from starters made on a stir plate as Kelsey does' date=' although maybe not even then. I don't think he was having major problems before he started using pure oxygen.[/quote']

Agreed, & he wasn't. wink

 

Ohh well the kids should enjoy the balloons! tonguebiggrin

 

Cheers,

 

Lusty.

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No I wasn't having any problems prior to using pure oxygen although I have noticed the beers done with this have come out cleaner in flavour (not less flavour' date=' just cleaner), especially the pilsners. They've improved a lot. [/quote']

 

Hmm, interesting. I had wonder if oxygen might be needed when saving from starters, because of the stir plate.

 

It would sure be nice if someone who owns an oxygen set up and saves from starters would do a side-by-side test comparing oxygen treated to sloppy slurry. Hint, hint. whistlingwink

 

Cheers,

 

Christina.

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If I had the means to do a proper side by side test then I would even though a single data point doesn't really mean a lot (as evidenced by Brulosophy), but unfortunately my brew fridge only fits one fermenter so one of them would be fermented under different conditions, which would make the test invalid really. Testing something like that would require everything to be exactly the same on both batches except for oxygenation and yeast starter vs. no oxygenation and sloppy slurry. Even if I fermented both outside the fridge, it'd still be difficult with only one heat belt. Plus they wouldn't be able to be cold crashed at the same time.

 

I suspect the yeast in my latest pilsner enjoyed the added O2 though. It took about 48 hours to show any visible signs of fermentation, then went from 1.0504 to 1.025 in 3 days at 10.5C before stabilising at 1.014 a couple of days later after being allowed to rise to 18C. The one FG sample I've taken so far tasted bloody brilliant too, one of my best ones so far. I'll take another tonight to confirm FG and begin the cold crash on Wednesday.

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By the way, optimum pitching rates don't mean that the yeast don't reproduce in the main brew wort, because they do. You grow the ample amount of cells to be pitched in the starter or harvest it from fermenter trub or whatever, but this isn't the entire colony that ferments out the batch - the cell count increases significantly in the main brew wort once pitched.

 

This is why dumping new wort onto an entire yeast cake of the previous batch is a massive overpitch.

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