Using Gelatin for Clarity

[RussW]

A couple of questions about using Gelatin for clarity.
1. Adding to Secondary (carboy) method - if you don’t cold crash, when should you add the gelatin solution to the secondary and how long prior to kegging?

2. If you are adding the gelatin at kegging, do you need to cold crash first, or can you add gelatin solution to keg, pressure keg to 30PSI, purge, re-pressurize, then leave keg at room temperature until ready to chill/serve?

 

[marc1]

Gelatin works best when cold, so cold crash first, then add while cold. You can be carbing at the same time.

If I add gelatin, I add it to the keg while cold. If you are worried about O2 ingress, you can inject your solution through a gas out connect with a medicine syringe.

If you're purging to get rid of O2, one purge at 30PSI won't do it. 15x will.

 

[odie]

If you're purging to get rid of O2, one purge at 30PSI won't do it. 15x will.

why 15x ? I used to purge several times until I finally did some math. A couple purges gets most of it out.

the air we breath is 78% nitrogen, 21% O2 and 1% inert gasses... Standard atmospheric pressure is 14.7 psi at sea level (gauge reading zero).

I pressurize my kegs to 60 psi (gauge) and then purge. That's a 4:1 ratio. Bleeding all the pressure after is effectively an 80% purge of whatever gasses are in the head space...every time.

So my O2 percentage is about 4.2% (20% of 21%) in the head space after my first fill and purge. Every subsequent purge reduces O2 by a diminishing amount. Second purge leave 0.84% O2. 3rd leaves 0.168%. 4th is 0.0336%. 5th is 0.00672

You will never get is all out. the question is at what point is any residual O2 irrelevant?

 

[beernutz]

This was a pretty convincing test of the cold vs warm gelatin question: Gelatin Fining - Cold Versus Warm

I cold crash the fermenter using a CO2 filled balloon attached to the airlock to avoid air intake, then when cold I add gelatin and later keg into CO2 purged kegs.

I like to purge kegs by filling with starsan solution and pushing it out in with CO2. Since I use 2 kegs I'll daisy chain them and push the starsan from one into the other then out of the second into a bucket.

I have a clear draught (top of beer pickup) system in one keg and force carbonate around 20psi so I'll generally have clear, carbonated beer a couple days after kegging.

 

[marc1]

why 15x ? I used to purge several times until I finally did some math. A couple purges gets most of it out.

the air we breath is 78% nitrogen, 21% O2 and 1% inert gasses... Standard atmospheric pressure is 14.7 psi at sea level (gauge reading zero).

I pressurize my kegs to 60 psi (gauge) and then purge. That's a 4:1 ratio. Bleeding all the pressure after is effectively an 80% purge of whatever gasses are in the head space...every time.

So my O2 percentage is about 4.2% (20% of 21%) in the head space after my first fill and purge. Every subsequent purge reduces O2 by a diminishing amount. Second purge leave 0.84% O2. 3rd leaves 0.168%. 4th is 0.0336%. 5th is 0.00672

You will never get is all out. the question is at what point is any residual O2 irrelevant?

That's up to the brewer. I like using fermentation CO2 because it's free, and there's a massive amount of it.

15 purges at 30 PSI gets you to ~10PPB O2 (assuming you have pure CO2, which is another whole can of worms)

https://www.homebrewtalk.com/threads/keg-purging-with-active-fermentation.628658/#post-8004741

 

[odie]

Interesting link...basically a lengthy explanation of what I just said. You can chase that dragon all you want, I doubt you will ever get all O2 out.

A few burst and purge cycles should be all you ever need. You can go down that rabbit hole forever...

perhaps toss a little sugar in the keg before purging? let the yeast eat whatever O2 is left? It's my understanding that yeast does "eat" O2 as well as sugar?

maybe someone can speak to yeast and O2 in the keg...people do use it for natural carbonation...

 

[Rob2010SS]

I prefer to add gelatin to the keg, once the beer is cold. I use a syringe with tubing connected to a gas QD on the keg so that you don't have to open the keg.

 

[hottpeper13]

The refermentation in the keg will take up the 02 that might have gotten into the liquid but wont do anything for it in the head space.

 

[odie]

The refermentation in the keg will take up the 02 that might have gotten into the liquid but wont do anything for it in the head space.

gotcha...so "priming" the keg will not purge any O2...just gotta blast a vent a few times regardless

 

[renstyle]

A couple of questions about using Gelatin for clarity.
1. Adding to Secondary (carboy) method - if you don’t cold crash, when should you add the gelatin solution to the secondary and how long prior to kegging?

With no cold crash during fermentation.... but ending in a keg, I'd just add the gelatin to the keg (opt #2).

For the vast majority of brews a secondary provides an additional clarification step that most have moved to a cold crash step instead.

2. If you are adding the gelatin at kegging, do you need to cold crash first, or can you add gelatin solution to keg, pressure keg to 30PSI, purge, re-pressurize, then leave keg at room temperature until ready to chill/serve?

Add gelatin solution to the keg.

Do however many burst/purge cycles you feel comfortable with to clear the majority of the O2 from the headspace.
- as math and others have mentioned 15x purge cycles at 30PSI will get you in the 10 parts-per-billion range on O2.

Start conditioning (chilling).

If you are adding gelatin at kegging, you do not need to cold crash first, but doing so does improve clarity since crashing will allow the larger particulates to floc out first, leaving less for the gelatin to deal with... also the gelatin likes cooler (50F or lower) temps.

 

[renstyle]

Interesting link...basically a lengthy explanation of what I just said. You can chase that dragon all you want, I doubt you will ever get all O2 out.

A few burst and purge cycles should be all you ever need. You can go down that rabbit hole forever...

<Points to article full of maths> That post is a CLASSIC!

A 15x burst/purge will get you to the same level of O2 that a keg would have if filled only with fermentation CO2 from a typical 5gal batch.

That's where the 5-10 ppb figure arises.

You certainly do not need to take it to that extreme, but many do, especially since you can get there with little to no work if using ferm CO2.