Avoiding oxygen in mash: Intert blanket? Vacuum?

[TechFanMD]

I do not do LoDo, but it intrigues me. On the cold side, we all try to avoid oxygenation, and I think a lot of the issues on the cold side are pretty well agreed upon regardless of whether you agree with LoDo or not.

The Mash is the part that I am curious about. I understand removing oxygen from the water, and taking extra care in milling, capping the mash, etc. I still can't wrap my head around how the water doesn't just get re-oxygenated by all of the O2 in the grains.....that's a lot of air gaps and surface area.

So my question: Does anybody just create an enclosed area purged with CO2? Given some of the equipment and lengths people go to, it wouldn't seem hard to pull a small level of vacuum on a mash tun with the milled grains inside, purge with CO2 (maybe vac/purge a few times) then actually pull the pre-boiled water in for underletting by vacuum (evacuating the air in the MT basically having higher atmospheric pressure outside the tun push the water into the mash tun).

Similarly, does anyone just mill under some inert gas by making a small glove box or just having the mill on/off remotely operated and milling in a box purged with nitrogen, CO2, argon, or whatever is available? The area of this box would not have to be terribly large really....

It seems like these would be significantly better methods to avoid oxygen than what I've read here and elsewhere.....many methods of which I just can't wrap my head around them actually having significant effect on O2 levels.

 

[sixhotdogneck]

I still can't wrap my head around how the water doesn't just get re-oxygenated by all of the O2 in the grains.....that's a lot of air gaps and surface area.

The water is underlet which pushes the O2 up and out of the vessel, of course it picks up O2 along the way but that's what the antioxidants SMB and perhaps Ascorbic Acid are for. After which the mash cap aids in keeping O2 at bay.

 

[sixhotdogneck]

So my question: Does anybody just create an enclosed area purged with CO2? Given some of the equipment and lengths people go to, it wouldn't seem hard to pull a small level of vacuum on a mash tun with the milled grains inside, purge with CO2 (maybe vac/purge a few times) then actually pull the pre-boiled water in for underletting by vacuum (evacuating the air in the MT basically having higher atmospheric pressure outside the tun push the water into the mash tun).

Similarly, does anyone just mill under some inert gas by making a small glove box or just having the mill on/off remotely operated and milling in a box purged with nitrogen, CO2, argon, or whatever is available? The area of this box would not have to be terribly large really....

I believe a gentleman (was it Die_Beerery?) has a purged system developed with Stout Tanks but I'm not sure about the grain milling portion.

 

[Big Monk]

I believe a gentleman (was it Die_Beerery?) has a purged system developed with Stout Tanks but I'm not sure about the grain milling portion.

Righto.

We don’t typically advocate out front with vessel purging because not many people have a setup to handle it.

But yes, you can purge the mash tun with the grain it then fill.

 

[TechFanMD]

The water is underlet which pushes the O2 up and out of the vessel, of course it picks up O2 along the way but that's what the antioxidants SMB and perhaps Ascorbic Acid are for. After which the mash cap aids in keeping O2 at bay.

I realize that - but it is still coming into an enormous surface area of O2 laden grain and air voids as it comes up. In my mind, even underletting is a very weak link in keeping O2 out. Just still water will reoxygenate to some extent pretty quickly - I would think pushing it into grain would almost undo the deoxygenation of the pre-boil.

That's why I wonder - my not just take a good portion of the O2 out of the grain before underletting? Then antioxidants aren't necessary either.

 

[TechFanMD]

Righto.

We don’t typically advocate out front with vessel purging because not many people have a setup to handle it.

But yes, you can purge the mash tun with the grain it then fill.

Thanks. It doesn't seem like it would take much vacuum with a few purges to significantly reduce the amount of oxygen in the grain and tun.

 

[MaxStout]

I suppose you could adapt the vessel with an inlet and outlet tube. Have a small vacuum pump draw air out of the outlet while you pump CO2 into the inlet. You'd have to guess at what point you have a mostly CO2 atmosphere inside.

I don't know of anyone milling grain in an inert environment, though someone has probably done it. You can mitigate oxygenation of the grain by milling it right before you mash in.

 

[PlinyTheMiddleAged]

I make an attempt to mill into a CO2 purged mash tun. It’s far from perfect, but this is what I do.

First, I BIAB full volume mash and I don’t underlet, so I have that working against me. Instead, I pre-boil my strike water to drive the DO towards zero. With my BIAB bag in place and my salts and sodium metabisulfite added, I put a piece of plywood over the top of my mash tun. The plywood “lid” has a hole cut it it that matches the output hole of my grain mill. There’s another hole just big enough for a piece of tubing from my CO2 bottle/regulator to fit through. In goes the tubing and I let CO2 purge the head space in the mash tun. Then I grind my conditioned grain directly into the pre-heated liquor.

After grinding the grain directly into the water through the purged atmosphere, I give a gentle but thorough stir, carefully purge the mash tun headspace again, put my mash cap on, purge again, put the lid on my mash tun, and wrap the whole thing up in sleeping bags for the duration of the mash. I may stir again in about 30 minutes if I remember to do so (re-purging if I do).

I hope the above makes sense. It may sound complicated, but it isn’t at all. I’d attach pictures if I had any - those would be a lot easier to follow than my babbling. I’m brewing on Sunday and could snap a few pics if needed.

Anyway, my process is far from perfect, but after implementing hot side practices, my IPAs are pretty darn good. And they stay good for a few months.

Good luck - the reward of low oxygen brewed beers is worth the small effort.

 

[Die_Beerery]

I suppose you could adapt the vessel with an inlet and outlet tube. Have a small vacuum pump draw air out of the outlet while you pump CO2 into the inlet. You'd have to guess at what point you have a mostly CO2 atmosphere inside.

I don't know of anyone milling grain in an inert environment, though someone has probably done it. You can mitigate oxygenation of the grain by milling it right before you mash in.

Alot of larger breweries do, namely German.. but SN does it here, along with others.

I run automation to purge my vessels. I have vacuum pumps hooked up, along with prvs and N2.

N2 purge lines in my system are the red lines, they are connected to 1 way check valves and solenoids. You can also see the Vac pumps, and prv's. The kettles are sealed and you can see the pressure sensor in the vessels. I pressure up to 10psi, then blow off. I then pull a vac with the vac pumps. Then pressure up and repeat over in the HLT stack you can see headspace oxygen. I also measure DO, PH, gravity, flow, in realtime.

 

[Hannabrew]

Bryan, in your pre-Stout days did you ever measure DO after underletting without sulfites?

 

[Die_Beerery]

Bryan, in your pre-Stout days did you ever measure DO after underletting without sulfites?

Without sulfites and no purging or?

 

[Hannabrew]

Pre boil, no sulfites, no Purge

 

[Die_Beerery]

At best .75, but no lingering fresh malt flavors.

 

[Bilsch]

I nitrogen purge the grain but do it without the vacuum pump. I dump the gas in under the false bottom and the flow is upward through the grain bed escaping through the gap at the mashcap. Certainly vacuuming the vessle would be better and consume less N2 to get the job done.