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Jun 08, 2022 View:

Question for those who oxygenate their wash

How many liters/min do you run with in-line oxygenation?

I ran as high as 4 liters/minute (in an effort to solve some previous fermentation issues) and saw pretty decent attenuation (from 18 plato down to 2) on my last batch, but was concerned that I might be running the o2 a bit high at some detriment to my wash. I'm around 2 months into this and just trying to get my procedures completely dialed before subtantially upping production.

After doing some reading I've come to understand that brewers will run typically 1-2 liters but that is over the course of their wort being transfered from boil kettle to fermenter, which i assume is a bit faster paced than the 90+ minutes that I'm sparging, running through hx, then into a fermenter.

Any thoughts/opinions/facts on appropriate levels of in-line o2?


Reply:

What temp are you pitching at? What's your pitching rate (how many cells per ml)? What's your starting gravity?

Some yeast strains like more, and some like less. Remember, too, that you're fermenting more sugars than brewers are because you're fermenting 100% of available sugar (hopefully, anyway) whereas they are leaving residual sugars behind. In other words, you're asking your yeast to do ~20% more work than brewers are.

Oh, and are you adding yeast before you add oxygen? And how are you measuring how much 02 you're adding?


Reply:

I do not oxygenate other than wort splashing into the fermenter, I shall watch this discussion and hopefully learn something.

What are you fermenting?

I assume it is grain since you are sparging.

Can someone please explain why additional oxygen is needed.

Thanks


Reply:

Oxygen is needed for sterol synthesis, which is a fancy way of saying.... yeast cells need it to create daughter cells, boost your yeast count, and ensure that the yeast is healthy and active enough to completely ferment the substrate.

You can either add oxygen to the mash/wort, or you can "overpitch". Some distilleries add it, some don't. Unaware of any breweries that don't oxygenate before or during pitching.


Reply:

Pitching Temp: 80F.

Cell Count: Not sure of the cell count but the yeast manufacturer (Fermentis Safspirit American Whiskey yeast) recomends 50-80g/hectoliter -- With 250gallons of wash, I've been pitching around 700 grams (or aprox. 75g/hectoliter). I'm going to try to touch base with Fermentis and figure out what the actuall cell count per gram is - would be good to know.

Original Gravity: 1.075

I've been oxygenating in-line just before the entry point of my fermenter. Once I acumulate 30 or so gallons, I've been pitching a bit of yeast to get things going and, in theory (although my theory is often flawed)... help protect the wash by adding the good guys before anything else tries to mingle. O2 has been measred thus far strictly by the guage that offers up a liters/min reading. Is there another way that I could/should be measuring oxygen?

Pete, I'm fermenting a wash from 100% malted barley —but— 15% of my grain bill is made up of varying amounts specialty malt. I'm figuring that I'll end up on the slightly lower side of completely available fermentable sugars due to the high percentage of crystal — it's yeilding some kick ass flavors though.

Todd, any thoughts on the pitching rate I'm running vs. the O.G. and oxygen implimentation? As stated before... just looking to tighten things up as much as posible before plowing full steam ahead. Thank you for taking the time to field this one.

Btw. I finally tracked down a bottle of your rye. Wonderful stuff! I'm officially issuing request for greater distrobution throughout Chaffee county.


Reply:

It could be that your adding such a high amount of specialty grains that your terminal gravity is simply stopping at 2 Plato because of unfermentables from such a large amount of crystal or other malts.

But, as you say, it's worth your time to up the pitching rate and oxygen to see if you can drop the plato down a tad further. If it doesn't drop the terminal gravity, you can return to your initial rates. 80F wort isn't going to hold very much in the way of dissolved oxygen, and that's a pretty high gravity for that pitching rate.

How long does it take for you run through the heat exchanger? 1 hour? Using a sintered carbonation stone and compressed air? If so, IMHO, 4 liters/min is too low.

This is all just my opinion.


Reply:

I run fairly slow throught my heat exchanger - maybe 8 gpm. I'm sparging pretty slowly too (usually takes close to 90+ mins) becasue my hot water comes straight from an on demand water heater witch only spits 3 gpm of hot water. Convienient to not rely on a hlt, but not so speedy. I'm pushing oxygen (medical grade) through a stainless sintered stone.

I appriciate the opinion. I'm going to take a shot at upping the pitching rate, blasting in 6-8 liters/min of oxygen, and dropping the wash temp down a bit in hopes of better O2 retention. Worth a shot! Thank you.


Reply:

At 90 minutes of knockout time, 4 liters per minute might be ok.

If you're happy with the profile of your white dog pitching at 80F, might I suggest adding 02 directly to the fermenter for another 30 minutes with the yeast in, and leave the pitching temp alone? Dropping the temperature of the wort a few degrees will have a negligible effect on the dissolved oxygen. However, adding 02 directly to a fermenter pitched with yeast will increase oxygen consumption by your yeast markedly. Changing the pitching temp could alter the congeners that your yeast produces, and it seems that you're quite happy with your new make.


Reply:

A note for PeteB, you can experiment with the effect of mash aeration relatively inexpensively by using your air compressor, a 0.02 micon inline filter http://www.northernbrewer.com/shop/in-line-sanitary-filter.html and preferably a sintered SS stone (even that can be skipped for the experiment). Using straight oxygen is great but you can easily over oxygenate, a problem for beer but for spirits it's more of a cost issue; if you just use filtered compressed air your expense is minimized and you can get very similar results. I've also read about the benefits of aerating the wash immediately prior to addition to the still, this makes the wash more reactive with the copper thereby removing more sulphur compounds. I haven't experimented with that myself yet but I do use compressed air for mash aeration and it's very effective.


Reply:

I probably would have gone the compressed air route had I not found a really good hookup from a local oxygen supplier who is facinated with distilling.

I've also read about the benefits of aerating the wash immediately prior to addition to the still, this makes the wash more reactive with the copper thereby removing more sulphur compounds. I haven't experimented with that myself yet but I do use compressed air for mash aeration and it's very effective.


Reply:

Can't pass up a good deal on O2. The info on mash aeration is a brief reference in the Handbook of Alcoholic Beverages Series, Whisky: Technology, Production and Marketing, pg 196-198. They mention its use for reduction of sulphur compounds as well as precursors of ethyl carbamate.

If you're in Maine you should definitely swing by.

www.facebook.com/NewEnglandDistilling

newenglanddistilling.com (coming soon)


Reply:

Thanks for that Ned. I will give air a try.

As for cheap in-line air filters, it is common practice in this part of the world for divers to use "modess sanitary napkins" stuffed into a piece of pipe.

I have seen a lab air test and they work very well.

If the air is good enough to breathe under pressure then I assume it should be good enough for yeast.


Reply:

That's pretty good! I'd hate to see what would happen if they inhaled too hard...

So from the posts above, I'd bubble up through the fermenter drain valve so you're getting decent turn over at the top of the mash/wort, don't need to go crazy. If you're at fermentation temp run it for 1+ hr and use it to mix the fermenter after you pitch the yeast. you should see a reduction in the lag phase and a good vigorous fermentation.


Reply:

So from the posts above, I'd bubble up through the fermenter drain valve so you're getting decent turn over at the top of the mash/wort, don't need to go crazy. If you're at fermentation temp run it for 1+ hr and use it to mix the fermenter after you pitch the yeast. you should see a reduction in the lag phase and a good vigorous fermentation.


Reply:

I like that idea, should work well in a conical fermenter, for example. Just make a TC cap with bubbler to attach on the exit valve?


Reply:

I've read you can't over oxygenate just using air. Anyone here have any experience in how much cooling you can get from aeration?

I'd be curious if you could keep pumping air through your hot wort until it reaches a pitching temperature, and if that could be a practical alternative to using a heat excanger or other cooling mechanisms.


Reply:

I would say not much cooling, air isn't great at heat transfer and you'd have to pump a lot of air to get any significant temp drop. I'd also be cautious adding air to hot grain mash or wash because if you're not pitching a ton of really happy yeast you may find that you're doing more harm than good. The oxygen in the hot mash/wash can lead to the creation of some pretty undesirable off flavors like stale papery flavors and even DMS. Big issue in breweries, I try to keep them to a minimum in the distillery.


Reply:

We use bottled oxygen at Berkshire Brewing, an air compressor gives you air but the bottled oxygen is.... Well...... Oxygen. The yeasties want oxygen. Some small brew pubs use oil less compressors but the fermentations lag.... Too slow a ferment makes funny tasting beer....and I would imagine funny white dog.....


Reply:

No doubt O2 is good stuff but I'd argue that it's not necessary. O2 is taken up by the yeast in the growth phase of the fermentation to help create good flexible, permeable cell walls. The more O2, the more yeast you'll grow; and here's the kicker, the more yeast you grow the less alcohol you produce because the yeast uses all the good food you gave it to make more yeast rather than alcohol. There's absolutely nothing wrong with using O2 you just really need to monitor how much you pump into the mash, it is very easy to blow right past 8 ppm (ideal mash/wort O2 concentration) when you're pushing straight O2. Using filtered compressed air is considerably cheaper, provides plenty of O2, and you're much less likely to overshoot on the concentration because O2 only makes up 21% of air. I would guess the brewpubs that you're referring to either under pitch or under aerate or both and so experience a sluggish fermentations. Personally, I choose air and a big pitch of healthy yeast, less for me to worry about. All that said, drayman, you guys make some great beers down there and so make a strong case for O2. Great beer = greater whiskey


Reply:

how are you monitoring your O2 levels?

Brad


Reply:

Has anyone ever tried using an Oxygen Concentrator? It's a machine that takes room air, purifies it, condenses it and delivers about 95% pure O2 at 4 lpm. You can get about 90% at 6 lpm. The initial investment is hgher (roughly $500.00 for an new unit), but saves you $$ in the long run and you don't have to worry about bottled O2 and the fire hazard they present. If you check with a local home health care company, they may even have used ones they will sell for $100 bucks or so. The only issue I can see with using this is the keeping the fine particulate filter clean.


Reply:

http://www.amazon.com/gp/aw/d/0937381969

30 ppm of o2 is what I recall from the book, Yeast = chris white. You'll need a dissolved O2 meter or just a rough volume/time calc. For how long to run compressed air through a filter to your diffuser. At the speed you are running your wort, you may be able to use a wort chiller with a diffuser built in the breather.


Reply:

No doubt O2 is good stuff but I'd argue that it's not necessary. O2 is taken up by the yeast in the growth phase of the fermentation to help create good flexible, permeable cell walls. The more O2, the more yeast you'll grow; and here's the kicker, the more yeast you grow the less alcohol you produce because the yeast uses all the good food you gave it to make more yeast rather than alcohol.


Reply:

There has always been some mystery surrounding exactly what goes on inside our fermenters but we’re learning more and more as the years progress so my info may be outdated. That said the comment I made on yeast growth at the expense of alcohol yield was not something I just made up; it was taught to me at Siebel when I attended in the 1990’s and it can be found on page 479 of Brewing: Science and Practice (Woodhead Publishing in Food Science and Technology) by Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes and Roger Stevens as well as page 141 of Whisky: Technology, Production and Marketing (Handbook of Alcoholic Beverages) by Inge Russell, Graham Stewart and Charles Bamforth.

Related to O2 concentrations, I don’t brew high gravity mashes so the 8 ppm (albeit theoretical) is all I need. Some people who do high gravity brewing do in fact give a second shot of O2 as Stevea suggests, but I can’t really comment on that as it’s not my preferred method.


Reply:

There has always been some mystery surrounding exactly what goes on inside our fermenters but we’re learning more and more as the years progress so my info may be outdated. That said the comment I made on yeast growth at the expense of alcohol yield was not something I just made up; it was taught to me at Siebel when I attended in the 1990’s and it can be found on page 479 of Brewing: Science and Practice (Woodhead Publishing in Food Science and Technology) by Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes and Roger Stevens as well as page 141 of Whisky: Technology, Production and Marketing (Handbook of Alcoholic Beverages) by Inge Russell, Graham Stewart and Charles Bamforth.

Related to O2 concentrations, I don’t brew high gravity mashes so the 8 ppm (albeit theoretical) is all I need. Some people who do high gravity brewing do in fact give a second shot of O2 as Stevea suggests, but I can’t really comment on that as it’s not my preferred method.