Dry Hop Questions (using magnets)

[Gee Tee]

I have a question about dry-hopping by attaching hops etc to the inside of the lid using food magnets on brew day. When releasing the magnet a week before bottling, does it not infect the beer? I was going to sanitize the magnets, but am cautious of sanitizing the bag in case of flavoring the brew. I’ve not seen any mention of this on the internet.

 

[DuncB]

Hi I started by vacuum sealing normal magnets in plastic bags so they didn't come into contact with the wort / ferment.
Then moved onto sous vide magnets that are in food grade silicone.

I sanitise the bag and the magnets before loading with hops you could do this by boiling I suppose but I just use starsan.

Picture shows current hops waiting to be put in. I drag the hops down into the ferment and then can waft them around using the magnet on inside and outside and lift them out when finished to drip dry.

 

[Gee Tee]

That's brilliant - Thank you!

 

[MaxStout]

You could use stir plate spin bar magnets. Those are usually encased in some inert plastic.

 

[Spivey24]

Nice. Never heard of sous vide magnets. So something like this?

(8-Pack) Sous Vide Magnetical Weights Works on All Sous Vide Machines, Silicone-Coated Sous Vide Magnets https://a.co/d/4byBddW

 

[DuncB]

Nice. Never heard of sous vide magnets. So something like this?

(8-Pack) Sous Vide Magnetical Weights Works on All Sous Vide Machines, Silicone-Coated Sous Vide Magnets https://a.co/d/4byBddW

They look identical to mine, I just use them inside, just visible on the right in my picture. On the outside I'm using old PC harddrive magnets which are super strong.

 

[scogan]

I have done it by just putting a teaspoon in with the hops and hard drive magnets on outside .

 

[tracer bullet]

I also do the magnet thing. I need to cover mine or get some already coated. Thus far it's just crossing my fingers that the, I believe, nickel plating doesn't come off. They appear fine so I've been lazy.

I use Iodophor to sanitize my hop bag, the magnet that goes inside, as well as my hands (on which I have nitrile gloves) when I put my drop hop bag together. I do this when I've got a small old SS pot of the solution out that will be used for preparing my fermenter.

Folding the bag is always an interesting exercise. Small enough to keep it out of the beer for a while but not so small it won't unfold later.

 

[whattabrau]

I steam the bag which I reuse over and over. I'm not convinced that steaming is necessary for a new bag. Probably just gives you the warm fuzzies. If there's leftover organic deposit in a seam in an old bag, steaming -- unlike sanitizer -- should kill everything there.

Hmm, thinking about it now, I probably should start using a piece of cheesecloth to avoid the hard-to-clean bag seam.

I don't use the magnet trick, though. Dropping the bag quickly in towards the tail end of fermentation has worked fine for me. The comparison I have is hanging it from the keg lid, using fermentation to purge the keg, and then filling the keg with closed-loop transfer (more or less isometric to drop-by-magnet). Can't say I notice a difference between the results for the techniques, which leaves me to think that quickly opening the fermentor to dryhop is fine, with the only annoyance being that you don't have a long window for doing it.

 

[tracer bullet]

I don't use the magnet trick, though. Dropping the bag quickly in towards the tail end of fermentation has worked fine for me.

I've been considering this as well. The idea being 1) I can purge with CO2, I have it handy, and 2) With some active fermentation producing CO2, that helps as well.

I used to think that the yeast would consume any O2 and not allow it to oxidize the beer, but now I'm not so sure, I think that happens earlier in the fermentation process?

On the flip side if I have magnets and don't need to open the lid, I should just stick with that process.

 

[whattabrau]

I used to think that the yeast would consume any O2 and not allow it to oxidize the beer, but now I'm not so sure, I think that happens earlier in the fermentation process?

Yea I don't think yeast takes care of anything you throw at it, but in this case you're still venting the headspace, i.e. a good portion of that oxygen will escape the fermentor, and if any remains in the headspace, it's unlikely to fully dissolve in a few days. I also keg-condition pretty invariably, so the second fermentation may help. That said, even a tiny bit of oxygen in the headspace can be pretty dramatic a few months later, as I've experienced with a bottle headspace purging experiment.

If you have a working process you don't find labor-intensive, probably not worth changing it, but it seems like OP didn't yet have one.

 

[dtashmore547]

I use neodymium magnets they are chromium plated and don't react with the brew, I pressure ferment and don't want to lose the pressure by opening so this helps and allows for dry hopping without losing pressure or opening for air ingress. for those who are fearful of getting oxygen in the headspace I don't think it should be an issue as oxygen is lighter than co2 so should be evacuated by ferment or injected co2.

 

[DuncB]

Mythbuster alert.
Oxygen will equilibrate within minutes not days.
Oxygen and CO2 mix they DO NOT form layers.
If they did wouldn't a lot of people die when they went in a basement or into a cave as it would have filled up with that heavier CO2.
I admit deaths have been reported from CO2 when multiple fermenters have been used in a basement but this is not quite the same.

 

[CascadesBrewer]

You could use stir plate spin bar magnets. Those are usually encased in some inert plastic.

I tried this. Due to how stir plate magnets are made they don't provide much hold. One end of the stir bar magnet is attracted and the other is repelling.

The first time I tried this technique I used some Neodymium Disc Magnets. I noticed some corrosion on the magnet inside the beer, and I read about concerns about the metals that might be used. Another flaw is that they are both incredibly powerful, and also incredibly fragile. Vacuum sealing them in small bags should help with the corrosion issue and the breakage issue. I have a vacuum sealer now, but...

After a failed attempt trying to get stir plate magnets to hold a hop sack, I picked up a set of the Sous Vide magnets. The are a pretty good fit for this usage. I got this 4 pack for $13: https://a.co/d/8HQUvIn

I would use these more often, but I am often starting with 2.7 gals of wort in a 3 gallon Fermonster (which tops at around 3.2 gals). There is not a lot of room in the headspace for the hops. They work a lot better with 5.5 gals of wort in a 7 gallon Fermonster. I just got some 8+ gal stainless steel fermenters where these should work great).

 

[Bassman2003]

I have been experimenting with this technique and have had good results but am still looking at magnet approaches.

1) To sanitize the hop bag, I set aside a plastic ice cream container (empty) and sanitized it. The night before brewing I dip my hop bag in Starsan, ring it out then place it in the plastic ice cream container to dry out overnight. When I get to placing the hops in the fermenter the next day the bag is dry.

2) I have been using a Foodsaver sealing approach with the magnets but the Foodsaver bag does not fair well in a pressure ferment. The plastic is thoroughly stained and is puffed up when it comes out. Strange as the seal in still intact but the vacuum is gone.

3) I will try the sous vide magnets next as pressure fermenting IPAs is so much better that I will never make an IPA again without pressure.

 

[tracer bullet]

Oxygen will equilibrate within minutes not days.

Agreed. Except I might even say it occurs in seconds.

To be clear, in case anyone considers a process based on this discussion, purging would need to mean a process that occurred multiple times or was at least a very lengthy single time. Slightly pressurize with CO2, burp, and repeat until satisfied - each time will get rid of more O2. Mind the burping though, an open port will allow O2 in, maybe even allow it to come in while CO2 is blowing out.

 

[whattabrau]

Agreed. Except I might even say it occurs in seconds.

There's nothing to agree or disagree on. You can look up the air-CO2 diffusion coefficient for a number of temperatures e.g. from the CRC handbook. Notably, it gives the *minimum* rate of mixing, as it does not account for air movement (or CO2 escaping the beer, but we'll ignore that so that we get a humorous climax at the end of this paragraph). If someone wants to be really pedantic, it's the *probable* minimum rate. There is no law of physics saying that mixing two substances can't separate them, but anyone who's ever mixed something will quickly tell you that counting on that probability is not a viable strategy for brew oxygen management.

 

[DuncB]

@Bassman2003
The bag puffs up because gas can permeate through the bag.
I have noticed a sousvide magnet was a bit puffed up with gas after several weeks in a fermenter under pressure. It deflated on removal over about a day.
There's no need for the bag to be dry before you put the hops in.
Boil the bag if you want or pressure cooker then dip in starsan before filling it up.
I wouldn't put a naked magnet of any type into an acid environment of wort or beer.
Dipping in some molten food safe plastic would be another option but not one that I was able to execute.
Restaurants and cafes often have vacuum sealers and you could ask them to vac seal for a bribe. Homebrew shops also tend to have them.

 

[Bassman2003]

Thanks. Makes sense now. The CO2 is winning the gas battle and permeating the Foodsaver material while under 2 bar of pressure.

I was thinking the bag would best be dry because I do not want the pellets to start expanding any earlier than they have to. But I wonder about the state of the pellets in the fermentation environment anyway. They probably puff up fairly quickly while they are hanging there. Adding dry hops in this way is not ideal but the best I can do without a separate transfer keg type solution. Which in my mind would waste a lot of beer.

 

[Spivey24]

Got my magnets in the mail from that Amazon link. Going to give it a try tomorrow.
I guess the hops do ok sitting there for 10 days or so warm because they are sitting on CO2 basically?
I was also thinking instead of using a hop bag, use a plastic cup and just dumping them in loose.

 

[whattabrau]

Got my magnets in the mail from that Amazon link. Going to give it a try tomorrow.
I guess the hops do ok sitting there for 10 days or so warm because they are sitting on CO2 basically?

That's probably fine. If you homedry hops with the DIY method, you spread them out somewhere and fan them with air for several days.

If you're concerned, you can add them after high krausen. It'll also prevent a potential mess, in case you get blowout.

I was also thinking instead of using a hop bag, use a plastic cup and just dumping them in loose.

Make sure you have some way of leaving the hop particles in the fermentor. Cold crashing works for me.

 

[JAReeves]

This discussion has been very helpful.

I am currently drinking the Blonde Ale I added whole-cone hops to at Dry-Hop and I think the time spent getting them into the fermenter let in way too much O2. If I had used pellets, it would have been much faster and the purge might have been more effective. As it is, the aromas are basically shot, though the beer still tastes better than any other lawnmower beer I could buy for $2.00/gallon.

Putting a stainless spoon in the bag and using magnets to hold it until DH also means the spoon will drag the bag below the surface-a significant issue with whole-cone hops. Unless someone has an opinion of a better system, I will try this on my next hoppy beer.

 

[whattabrau]

This discussion has been very helpful.

I am currently drinking the Blonde Ale I added whole-cone hops to at Dry-Hop and I think the time spent getting them into the fermenter let in way too much O2. If I had used pellets, it would have been much faster and the purge might have been more effective. As it is, the aromas are basically shot, though the beer still tastes better than any other lawnmower beer I could buy for $2.00/gallon.

Dunno. I've fumbled pretty bad without any dramatic effect. Maybe you dry-hopped too late.

Putting a stainless spoon in the bag and using magnets to hold it until DH also means the spoon will drag the bag below the surface-a significant issue with whole-cone hops. Unless someone has an opinion of a better system, I will try this on my next hoppy beer.

One spoon is unlikely to do the trick for any reasonable hop-load, but it also depends on the bag and how you fill it. I use a number of them (pretty hefty ones) and it still doesn't even pretend to sink initially. If you can, test with water first, e.g. during brewday so that you don't waste the testing water and hops.