NEIPA stratification in the fermerter

[Agentgonzo]

but it is the surface area to volume ratio that matters.

Can you explain? Surface area of what?

 

[Sadfield]

If the result risks oxidation - well I've never tasted it.

It fundamentally will in respect to the first half of that statement. Oxidation is part of the staling process in most things. Browning of fruit or the decanting of wine. That's why NEIPA breweries purge all vessels and piping with CO2 when packaging.

As for the second part. One or more may apply.

1) The beers you brew are less susceptible.

2) The effect is below your flavour threshold.

3) If you've maintained the same process, you've never not tasted the degree of oxidation in your beer. It's your norm.

 

[Agentgonzo]

Every brewing question will have several different answers all of them right and all of them wrong to someone.

And many of them irrelevant answers to a completely different question

 

[Sadfield]

And many of them irrelevant answers to a completely different question

That's down to the quality of the question. The problem is with posing the question to get the answer you want, not asking the questions to get the answer you need.

 

[The-Engineer-That-Brews]

Can you explain? Surface area of what?

Sure: apologies if I was a bit cryptic. What I meant was that if you ignore effects like temperature, the rate at which oxygen is absorbed into a container of liquid (e.g. in terms of mg oxygen per litre per sec), depends primarily on the surface area of the liquid exposed to the air. That rate will reduce as the liquid becomes saturated with oxygen, but it's true early on.
Once the oxygen molecules have passed through the surface of the liquid, they are constantly bombarded from all directions by the random impact of water molecules moving with thermal energy: at room temperature the average speed of a water molecule is about 1,300 miles per hour (!)
It is these constant, violent random impacts that cause the oxygen molecules to rapidly become dispersed evenly throughout the volume of the liquid. And it is because the force of these collisions is so much greater than the force of gravity upon the oxygen molecules, that the oxygen molecules remain evenly distributed and don't increase in concentration at greater depths

 

[Agentgonzo]

Ah ok . I thought you were talking about the diffusion rate of the hop compounds rather than oxygen molecules, but the same diffusion/Brownian motion applies to both I guess.

I remember seeing experiments at school about a vessel containing bromine at the bottom, and water in top. (Bromine is denser than water, so it's not an exact comparison). I remember that after a long time (again, I can't remember how long, but IIRC it was days/weeks) time, there was a small amount of diffusion but you could clearly see it wasn't homogenised (the bottom was still brown whilst the to was completely clear).

I was wondering whether a similar thing could have happened inside the fermenter with hop compounds not fully diffusing over the last few days of fermentation (without agitation, which was the case in my brew), but I haven't found any evidence either to support or disprove that theory. The bromine experiment isn't a fair comparison due to the differing density, and the permanganate experiment also isn't a fair comparison due to the short timescale (even though it does show uneven distribution in the 20°c tube)

 

[An Ankoù]

I don't brew or drink NEIPAs; they're not what I call beer, but I see a lot here and elsewhere and I certainly interested from a theoretical point of view. It seems to me there are two separate issues here: oxidation and "stratification". Starting with the second, I don't see any reason at all why the hop flavour shouldn't be stratified. Hop essential oils are not soluble in water but probably partly or wholly soluble in alcohol. Once the available alcohol is saturated, the rest would tend to float. So complete diffusion will be countered by the oils' tendency to rise to the surface. Not having used the crazy amount of dry hops required by an NEIPA I've never really sought to discern a difference between two bottles of lightly dry-hopped beer.
Oxidation is the scourge of hoe brewers, it would seem. Oxygen, apparently, is a recent discovery and we'd rest more soundly in our beds without it. Have real ale cask brewers and commercial keg brewers routine purged their vessels? Why have I heard nothing about bottling wands before these recent years? My experience is that the bottled is primed with sugar, which, together with the splashing effect, when the beer is poured into the bottle causes the dissolved carbon dioxide to come out of the beer causing al sorts of fobbing and foaming and natural expulsion of whatever horrors were in the bottle beforehand! Bottling wands were introduced to reduce this foaming weren't they? As for using a bottling bucket rather than bottling nearly-bright beer from the primary fermenter: I can't get my head around how this limits oxygenation.
Let's remember that excellent beer has been made for decades and centuries without the process methods encouraged today. Many of which are pulled down from industrial scale systems.

 

[Sadfield]

Let's remember that excellent beer has been made for decades and centuries without the process methods encouraged today. Many of which are pulled down from industrial scale systems.

But NIEPAs weren't, and the thread specifically relates to replicating a beer style that originates from being brewed on industrial scale systems.

Given that hopping during active fermentation to promote biotransformation is a characteristic of the style, perhaps stratification of hop oils in a liquid that has both CO2 off gassing and yeast flocculating is unlikely.

 

[Agentgonzo]

It seems to me there are two separate issues here: oxidation and "stratification". Starting with the second.

Thank you. I was indeed intending to discuss the second, not the first (which has been discussed many times).

 

[The-Engineer-That-Brews]

Hop essential oils are not soluble in water but probably partly or wholly soluble in alcohol.

I see what you're saying @An Ankoù and I'm no expert on hop flavours, but I think they might be esters and alcohols, not oils... e.g. see: https://www.researchgate.net/publication/270884543_Flavor_compounds_contributing_to_the_characteristic_flavor_of_new_aroma_hop_cultivars#read

 

[The-Engineer-That-Brews]

I don't brew or drink NEIPAs; they're not what I call beer, but I see a lot here and elsewhere and I certainly interested from a theoretical point of view.

Speaking entirely of personal preference (and not trying to convince anyone else) but I 100% agree, and my observations here are on the same basis

 

[Sadfield]

Speaking entirely of personal preference (and not trying to convince anyone else) but I 100% agree, and my observations here are on the same basis

Technically interesting, but otherwise a bit bland and one dimensional to drink, and thats when they are made well. The homebrew ones that have been, have all been made by people who have committed to ensuring their kit can do closed transfers and force carbonation, in my experience.

 

[An Ankoù]

Just to be thoroughly bad, I'm going to knock one up with open fermentation in a Yorkshire square, bottle it in old, clear Irn Bru bottles and dry hop it with Vimto.

 

[Agentgonzo]

Just to be thoroughly bad, I'm going to knock one up with open fermentation in a Yorkshire square, bottle it in old, clear Irn Bru bottles and dry hop it with Vimto.

I assume your grain bill will include reddybrek?

 

[Sadfield]

Just to be thoroughly bad, I'm going to knock one up with open fermentation in a Yorkshire square, bottle it in old, clear Irn Bru bottles and dry hop it with Vimto.

You won't get the correct flavour profile with Vimto. Original Um bongo hits all key tropical fruits.

 

[An Ankoù]

I assume your grain bill will include reddybrek?

For the oats? Not 'arf!!!

 

[Bolsover Brewer]

I too don't, or wouldn't consider making a NEIPA but I do make an IPA which has been dry hopped with more hops than the OP has used. The only noticeable difference is that with time the hop flavour does start to fade due to the volatility of the hop oils.
The wands they are a handy gadget for us home brewers, better than a piece of hose or having to squirt beer into a bottle.
While the oxygen isn't such the monkey on our back as it is the commercials it is still there and needs addressing. If we take care we can reduce oxygen in our beers but we can never eliminate it. The good part is the beer is drunk before the oxygen spoils the beer. (That is providing it is kept well)

 

[Neale]

I have a suggestion that doesn't seem to have been mentioned. Might bottle 2, (the one with the fruity flavour), have been filled closer to the top of the bottle than the other bottles? this is easily done when filling from a tap? and it does introduce a variable that hasn't been mentioned.

I know from experience that filling close to the brim of the bottle with hoppy beers will keep the hop character for much longer than filling an inch from the top of the bottle. I did a test on exactly this thats on the forum somewhere, and I have drank bottles over 100 days old that still had most of the hop character remaining. When bottles filled an inch from the top would loose their hop character after much less time. In fact I'm planning a pale ale next so I might do some test bottles to do a long term test with fill heights.

For clarity I fill directly from the FV using a bottling wand, I prime with a pre-prepared sugar solution and a syringe and fill to around 5mm from the top of the bottle.

 

[Agentgonzo]

It's certainly possible. I think I remember reading your post about that a while ago.

I tend to have about an inch of gas at the top of the bottle, but there will certainly be inconsistencies. Unfortunately there's no way to tell as the bottles long since been emptied... But I'll pay attention the the filling level when opening the rest of the batch!

 

[Jabber1]

I have a suggestion that doesn't seem to have been mentioned. Might bottle 2, (the one with the fruity flavour), have been filled closer to the top of the bottle than the other bottles? this is easily done when filling from a tap? and it does introduce a variable that hasn't been mentioned.

I know from experience that filling close to the brim of the bottle with hoppy beers will keep the hop character for much longer than filling an inch from the top of the bottle. I did a test on exactly this thats on the forum somewhere, and I have drank bottles over 100 days old that still had most of the hop character remaining. When bottles filled an inch from the top would loose their hop character after much less time. In fact I'm planning a pale ale next so I might do some test bottles to do a long term test with fill heights.

For clarity I fill directly from the FV using a bottling wand, I prime with a pre-prepared sugar solution and a syringe and fill to around 5mm from the top of the bottle.

Hey Neale,
Does filling so close to the top of the bottle not increase chance of the cap shooting off during carbonation? I was going to fill close to the top when bottling next but was wondering about possible issues.