Adding Sodium Metabisulphate at kegging effect on water profile

[royger]

Hello,

I've been recently adding sodium metabisulphate at kegging in order to prevent oxidation of heavy dry hopped beers. I also purge the keg and do closed transfer, but I thought that the addition of metabisulphate wouldn't hurt. I've just recently noticed however that it might have an impact on the final water profile of the beer, as the Brewfather brewing App has just added it into the mash water profile calculations as an ingredient, and adding it changes the content of Na and SO4.

Would this also apply when the sodium metabisulphate is added at kegging time?
Does metabisulphate turning into SO4 depend on whether there's oxygen in the beer?

I've been using a ratio of 0,1g/L, which means adding 1,9gr of sodium metabisulphate to a 5gal batch, but that seems to have a major effect on the final water profile, so I might want to lower the amount. Does anyone have other recommendations on the amount of sodium metabisulphate to use?

Thanks, Roger.

 

[Vale71]

Does anyone have other recommendations on the amount of sodium metabisulphate to use?

None at all.

 

[Omahawk]

I’ve been researching this to try when I keg my next hoppy beer this weekend. One of the Brülosophy contributors who does this said “for 5 gallons/19 liters of beer, it’s recommended to add 10 ppm SMB, which amounted to only 0.3 grams (1 gram SMB = 175 ppm/gallon)”.

http://brulosophy.com/2019/02/11/po...at-packaging-has-on-beer-exbeeriment-results/

 

[Vale71]

That experiment is as worthless as any other Brülosophy experiment or possibly even more. All we know is that some tasters correctly identified a difference in taste. There is absolutely no proof that what they were detecting was due to reduced oxidation and not the SMB itself.

 

[Omahawk]

That experiment is as worthless as any other Brülosophy experiment or possibly even more. All we know is that some tasters correctly identified a difference in taste. There is absolutely no proof that what they were detecting was due to reduced oxidation and not the SMB itself.

The longer I brew, the more I acknowledge I don’t know. All I do know is what I read from others experiences other and the collections of my 100+ brewing experiences. Like royger, I am open to trying it, as my hoppy beers lose their “zing” sooner than I’d like. royger asked for an SMB dosing rate, now he has one from someone with experience using this. And this one data point that seems to indicate non-shitty results using it. I do not believe there is anything in this article that purports to be “proof”.

 

[Big Monk]

None at all.

As crazy as this is going to sound, I have to say I agree here.

@royger
Reducing oxygen by mechanical means on the cold side is your best bet. If you are noticing changes in flavor that you think you can attribute to Na or SO4, it means you are still getting a significant amount of oxygen which is being scavenged by the Sodium Metabisulfite.

 

[Omahawk]

As crazy as this is going to sound, I have to say I agree here.

@royger
Reducing oxygen by mechanical means on the cold side is your best bet. If you are noticing changes in flavor that you think you can attribute to Na or SO4, it means you are still getting a significant amount of oxygen which is being scavenged by the Sodium Metabisulfite.

If the mechanical means aren’t getting enough O2 removed, any thoughts on adding some priming sugar in the keg for a similar “oxygen scavenging” action? Im in the same spot as the OP, doing what I can to minimize cold side oxygen but think there’s more to do.

 

[Vale71]

Those are all palliative measures at best. The only way to prevent oxidative damage is to get the total package oxygen at or below safe levels.

 

[Big Monk]

...it’s recommended to add 10 ppm SMB, which amounted to only 0.3 grams (1 gram SMB = 175 ppm/gallon)”.

In this case, ppm is equivalent to mg/l. 10 ppm is then:

10 ppm = 10 mg/l = 0.01 g/l * 18.93 l = ~ 0.19 g

175 ppm = 175 mg/l = 0.175 g/l * 3.785 l = 0.66 g (not 1g)

So Bru Crew can't do basic math either.

Now, @royger says 1.9g of Sodium Metabisulfite has been going into 5 gallons of finished beer:

1.9 g / 18.93 l = 0.1 g/l = ~100 mg/l = ~100 ppm (WAY TOO MUCH)

100 ppm not withstanding (that is a whopping dose), if you are "seeing" significant flavor impacts from either Na or SO4, it seems that you still have a significant level of oxygen intrusion, despite your best efforts.

Liquid purges, closed transfer and spunding are really your best bet and defense against cold side oxygen intrusion.

 

[royger]

I've been adding ~0.1mg/L following the guidelines from the vendor:

https://www.themaltmiller.co.uk/product/sodium-metabisulphite-100g-campden/
TBH I'm not sure I'm getting any noticeable flavour (since I don't have a batch without SMB to test against). I'm just worried that the water profile I tried to aim for it's completely skewed because I just add SMB later and greatly alter the amount of Na and Cl. So the Na and SO4 will only appear iff SMB bounds with oxygen then?

I'm already doing closed transfers with my CO2 tank and purging the keg with the CO2 generated during fermentation, so I would assume most of the SMB I add doesn't turn into Na and SO4?

I was just using the SMB because I'm extra paranoid with oxidation. I could try to account for the additional Na and SO4 that SMB will add, but if that only happens if there's oxygen there's a chance I would (again) get my water target off.

 

[Big Monk]

I've been adding ~0.1mg/L following the guidelines from the vendor:

https://www.themaltmiller.co.uk/product/sodium-metabisulphite-100g-campden/
TBH I'm not sure I'm getting any noticeable flavour (since I don't have a batch without SMB to test against). I'm just worried that the water profile I tried to aim for it's completely skewed because I just add SMB later and greatly alter the amount of Na and Cl. So the Na and SO4 will only appear iff SMB bounds with oxygen then?

I'm already doing closed transfers with my CO2 tank and purging the keg with the CO2 generated during fermentation, so I would assume most of the SMB I add doesn't turn into Na and SO4?

I was just using the SMB because I'm extra paranoid with oxidation. I could try to account for the additional Na and SO4 that SMB will add, but if that only happens if there's oxygen there's a chance I would (again) get my water target off.

A few points:

1.) That dosing appears to be for treating for chlorine. Also, you must have mistyped, as I have trouble believing you are adding 0.1 mg/l. Did you mean 0.1 g/l?

2.) If you are truly excluding oxygen to the best of your ability, skip the SMB at packaging altogether;

3.) Have you detected noticeable oxidation, hop fade, etc? If not, don't treat an issue that does not exist. Mechanical exclusion (proper purging, closed transfers, spunding, etc.) is all that is required, so if you feel you are getting oxygen intrusion, look to your purging and transfer methods and make the necessary improvements over dosing with metabisulfite .

 

[royger]

A few points:

1.) That dosing appears to be for treating for chlorine. Also, you must have mistyped, as I have trouble believing you are adding 0.1 mg/l. Did you mean 0.1 g/l?

Oh, yes, sorry. I indeed mean 0.1 g/l. The vendor lists 0.116g per litre as the antioxidant ratio.

2.) If you are truly excluding oxygen to the best of your ability, skip the SMB at packaging altogether;

The main worry I have is that I use an inline bouncer to prevent hop debris from clogging the keg post when racking. I try to flush the whole transfer line with the bouncer in the middle with CO2 before hooking it up, but I'm not sure how effective that is in purging the bouncer.

https://bouncer.beer/products/
I have the Bouncer MD “Mac Daddy” (not that the specific model matters much I think).

3.) Have you detected noticeable oxidation, hop fade, etc? If not, don't treat an issue that does not exist. Mechanical exclusion (proper purging, closed transfers, spunding, etc.) is all that is required, so if you feel you are getting oxygen intrusion, look to your purging and transfer methods and make the necessary improvements over dosing with metabisulfite .

I usually notice a bit of hop fade after 4 weeks maybe, but that's the only effect I can usually notice.

If I can ask, why is a spunding valve useful for closed transfers?

I usually hook the gas in post of the keg to a bit of line that has a ball valve at the other end that I open in order to let the CO2 out of the keg when filling.

 

[Big Monk]

If I can ask, why is a spunding valve useful for closed transfers?

I meant spunding in general, i.e. transferring with extract left to the serving keg. In conjunction with proper purging and closed transfers, spunding allows you to have added protection.

The three of them work in concert with one another and are all process based.

 

[DasBierBaron]

Why spund vs just carbing with dextrose?

 

[VikeMan]

Why spund vs just carbing with dextrose?

Done right, it avoids exposing the beer to O2.

 

[royger]

I meant spunding in general, i.e. transferring with extract left to the serving keg. In conjunction with proper purging and closed transfers, spunding allows you to have added protection.

The three of them work in concert with one another and are all process based.

Right. I think spunding would be hard to do for me ATM.

For example for IPAs I usually wait to reach FG, then drop temp to 14-15ºC to soft-crash yeast (in order to avoid over-attenuation when doing dry hopping), bring temp back to 18-21ºC, dry hop for 48h and then cold crash for 24h before kegging.

 

[Big Monk]

Right. I think spunding would be hard to do for me ATM.

For example for IPAs I usually wait to reach FG, then drop temp to 14-15ºC to soft-crash yeast (in order to avoid over-attenuation when doing dry hopping), bring temp back to 18-21ºC, dry hop for 48h and then cold crash for 24h before kegging.

What do you use as a fermenter? How are you adding the dry hops? Are you transferring finished beer? How are you carbonating?

 

[DasBierBaron]

Done right, it avoids exposing the beer to O2.

But how is it any different from using priming sugar in a keg? You can still use the same transfer process.

The reason I'm asking about it is that I have never had great luck with transfers on unfinished dry hopped beers due to clogged lines. It would be easier to to let the beer finished and settle, then transfer to a keg on top of priming sugar.

 

[VikeMan]

But how is it any different from using priming sugar in a keg? You can still use the same transfer process.

Can you can get priming sugar into the keg without introducing O2? I can't. You can hope the suddenly active yeast will use all the O2, but I have heard several pro brewers say that they won't use it all (and go to great lengths to exclude it).

 

[rsquared]

Can you can get priming sugar into the keg without introducing O2? I can't. You can hope the suddenly active yeast will use all the O2, but I have heard several pro brewers say that they won't use it all (and go to great lengths to exclude it).

With a carbonation cap, I've added gelatin without O2. Priming sugar should be the same.

• Add mixture to empty soda bottle.
• Screw carbonation cap most of the way on
• Squeeze bottle until just a tiny bit of liquid drips from the threads
• Tighten cap (should be essentially 0 oxygen now)
• Pressurize to 30 psi
• Attach a short ball lock to ball lock hose to the keg
• Turn bottle upside down and connect to the hose

With the bottle full of nothing but liquid and CO2, held upside down with the liquid against the cap, and at a higher pressure than the keg, as soon as it is connected the liquid will be forced out of the bottle.

 

[Big Monk]

With a carbonation cap, I've added gelatin without O2. Priming sugar should be the same.

• Add mixture to empty soda bottle.
• Screw carbonation cap most of the way on
• Squeeze bottle until just a tiny bit of liquid drips from the threads
• Tighten cap (should be essentially 0 oxygen now)
• Pressurize to 30 psi
• Attach a short ball lock to ball lock hose to the keg
• Turn bottle upside down and connect to the hose

With the bottle full of nothing but liquid and CO2, held upside down with the liquid against the cap, and at a higher pressure than the keg, as soon as it is connected the liquid will be forced out of the bottle.

The reason spunding is so nice is because you simply transfer the beer with extract remaining. A lot less involved than what you’ve described and you have the added advantage of actively fermenting beer providing the carbonation.

 

[DasBierBaron]

The reason spunding is so nice is because you simply transfer the beer with extract remaining. A lot less involved than what you’ve described and you have the added advantage of actively fermenting beer providing the carbonation.

Right, but then you have the problem of plugged corny posts. You also have to monitor fermentation and gravity very closely to get it right. The point of using the priming sugar is so you can let the yeast and hops settle before transfer.

 

[royger]

What do you use as a fermenter? How are you adding the dry hops? Are you transferring finished beer? How are you carbonating?

Sorry for the late reply.

I'm using a couple of Speidels (a 12L for 1/2 batches, and a 30L for full size batches), I've modded the lids and installed a ball lock gas post.

My usually flow is: ferment until it's fully attenuated, then attach the CO2 regulator set @ 1psi, soft crash to 15C, open the lid and add the dry hop charge. Purge the fermentor by setting pressure to 3psi and open the lid a bit to release pressure, do this 3 times, set the regulator again to 1psi.

After 36h start cold crash to 3C for 24h. I try to purge the whole transfer line (with the bouncer in the middle) with CO2 before doing the transfer by flushing CO2 at 5psi for 30s on one end of the line while having the other end unhooked. Then I just hook the bottom fermentor tap to the liquid out post of the keg, and leave the gas in post on the keg open while the beer flows from the fermenter to the keg.

I force carbonate by hooking my CO2 tank to the liquid out post and setting something like 35psi for 12h.

This has worked fine for me when doing dry hops of up to 5g/L, but if I try to get to higher dry hop ratios I would usually end up with less flavour than when doing 5g/L, and I think it's because beer oxidizes more due to the increased dry hop ratios.

Next time I will also push CO2 from the bottom tap on the fermentor when opening the lid to add the dry hop charge, so that I create a positive pressure and avoid any oxygen ingress, not sure how that will work. I will also try to flush the transfer line for longer. Anyone has any idea how to properly purge a transfer line with a bouncer in the middle?

Thanks, Roger.