What factors contributes to bubble size

[Sadfield]

Re: your second point - what forms the creamy head?

The rapid release of insoluble Nitrogen, due to the release of pressure. And then co2. Its all about promoting an instant head on a beer with low carbonation. Whether it be a pressurised keg or a can with a widget. Same with hand pulled cask, drawing air (largely containing nitrogen) through the beer, or even those ultrasonic devices. Without agitation the low levels of co2 are slow to be released and will happily remain in solution, not the nitrogen.

CO2 isn't that keen. The colder the beer more CO2 it retains as carbonic acid, even in beer prior to priming or force carbonation. That's why a mix is used rather than pure nitrogen. It makes keg Guinness dispensable without making it too fizzy, but the quick release of nitrogen replicates the head from hand pulled cask.

Same with Nitro Milk Stout from bottle.


"The key to making the Milk Stout Nitro work is pouring it hard and not tilting the glass. The point is to release the nitrogen. And in case drinkers have trouble figuring that out, the brewery added a QR code to its striking label that allows people to go straight to a video that shows them how pour."

https://www.westword.com/restaurant...s-craft-brewer-to-bottle-a-nitro-beer-5727867

 

[Bernie]

It requires a far higher pressure to get nitrogen into the beer but you can and I have.

It’s CO2 that rushes out, it’s very keen to get out into the world. For nitrogen the atmosphere is already over populated and so is far more relaxed about the whole thing. I’m always happy to be proved wrong though because I will have learnt something - any references?

Re: your second point - what forms the creamy head?

Liquids with lower surface tension will produce foam. Compare pure water and water with added detergent.

 

[Hazelwood Brewery]

The widget is different in that there is no dissolved gas involved. The widget contains gas at packaging pressure. The gas stays in the widget because the environment outside the widget is at the same pressure. When the can is opened there is a sudden drop in pressure and the gas in the widget escapes through small holes in the widget.

Hand pulls don’t drag air through the beer they pull beer from the cask, it’s the head space in the cask that draws in air to the cask.

CO2 (all gassed in fact) is keen to escape to the atmosphere at higher pressure and less fussed as the pressure drops. It’s also more keen to escape at warmer temperatures because it has thermal energy (at colder temperatures the energy is small and the molecules don’t smash into each other nearly so hard.

The hard pour is necessary to knock the nitrogen gas out of solution - as I said hard to get in reluctant to leave.

 

[Hazelwood Brewery]

Liquids with lower surface tension will produce foam. Compare pure water and water with added detergent.

You’ll get foam either way. Lower surface tension = larger shorter-lived bubbles.

 

[Sadfield]

The hard pour is necessary to knock the nitrogen gas out of solution - as I said hard to get in reluctant to leave.

Strongly disagree. Hard to get in, easy to remove.

It's all the same objective, guickly creating head whilst maintaining carbonation. Because no one drinks flat beer.

Why would they instruct people to rapidly remove nitrogen if its a replacement for carbonation, it makes no sense.

 

[Hazelwood Brewery]

Strongly disagree.

OK

Why would they instruct people to rapidly remove nitrogen if its a replacement for carbonation, it makes no sense.

Nitrogen produces a tighter creamy head, gives a better mouthfeel, smooths out bitterness. It does need a bit of encouragement though both getting it in (needs high pressure) and getting it out (squeezed through tiny holes or needs a hard pour). Makes sense to me and that’s why I do it.

 

[Bernie]

Strongly disagree. Hard to get in, easy to remove.

It's all the same objective, guickly creating head whilst maintaining carbonation. Because no one drinks flat beer.

Why would they instruct people to rapidly remove nitrogen if its a replacement for carbonation, it makes no sense.

Nitrogen is used to have a higher overpressure with less dissolved gas. Beers with a low carbonation will not form a head easily. In the can a widget is used to force the pressurised beer and gas to come through the tiny orifice and create many small bubbles. If CO2 only were used the beer would be too gassy as it would dissolve then foam up when the can or bottle is opened.

 

[Sadfield]

Nitrogen is used to have a higher overpressure with less dissolved gas. Beers with a low carbonation will not form a head easily. In the can a widget is used to force the pressurised beer and gas to come through the tiny orifice and create many small bubbles. If CO2 only were used the beer would be too gassy as it would dissolve then foam up when the can or bottle is opened.

This is exactly what i'm saying. Nitrogen beers, widgets, sparklers etc are all designed for head formation, nothing more, but we still want the correct level dissolved CO2 in the beer after dispense in order for it to not taste flat, whilst drinking through a creamy head for mouthfeel.

Nitrogen produces a tighter creamy head, gives a better mouthfeel, smooths out bitterness. It does need a bit of encouragement though both getting it in (needs high pressure) and getting it out (squeezed through tiny holes or needs a hard pour). Makes sense to me and that’s why I do it.

Yes, the head that nitrogen used to create, adds mouthfeel as does cream, frothy milk on coffee, ice cream on soda. The bitterness is smoother because less CO2 is used, so less carbonic acid forming on the tongue. As observed in soda water tasting more bitter than still, or flat cola tasting sweeter.

Now that you've acknowledged that it is the nitrogen, not the CO2 as you previously stated as rushing out, that forms the head, I'm still awaiting an explanation as to why only mixed gas is used. Why not use 100% nitro?

 

[Hazelwood Brewery]

Now that you've acknowledged that it is the nitrogen, not the CO2 as you previously stated as rushing out, that forms the head, I'm still awaiting an explanation as to why only mixed gas is used. Why not use 100% nitro?

You’ve misunderstood. My point was that the CO2 comes out of solution more easily. Any discussion involving nitrogen rushing out is either in the context of a widget (where nitrogen gas is forced through the beer) or in the context of nitrogen being forced out of solution by a perforated disk or hard pour. Note in these explanations I’ve used the word “forced”. Rarely would I need to force CO2 out of solution.

I can’t say why 100% nitro isn’t used - maybe it is, I haven’t researched it. My guess is that you can have too much of something or maybe you need the CO2 to provide a level of protection against oxidation while you’re trying to get nitrogen into the beer - which does take longer.

We have rather strayed from the point of this thread though.

 

[Bernie]

You’ve misunderstood. My point was that the CO2 comes out of solution more easily. Any discussion involving nitrogen rushing out is either in the context of a widget (where nitrogen gas is forced through the beer) or in the context of nitrogen being forced out of solution by a perforated disk or hard pour. Note in these explanations I’ve used the word “forced”. Rarely would I need to force CO2 out of solution.

I can’t say why 100% nitro isn’t used - maybe it is, I haven’t researched it. My guess is that you can have too much of something or maybe you need the CO2 to provide a level of protection against oxidation while you’re trying to get nitrogen into the beer - which does take longer.

We have rather strayed from the point of this thread though.

 

[Bernie]

The nitrogen is added as liquid nitrogen in the can. CO2 would be inevitably present as it would be dissolved in the beer.
As for the overpressure used on kegs, if pure N2 were used CO2 would come out of solution, giving a decarbonated beer. The CO2 partial pressure would be enough to maintain the carbonation.

 

[Sadfield]

We have rather strayed from the point of this thread though.

Carbonation, or Nitrogenation, and dispense seem like a very important part of the equation in answering the original question.

Despite the claims of bubble size between the two gases, I don't notice much difference between nitro keg and well served cask, pulled through a sparkler.

 

[Donegal john]

You’ve misunderstood. My point was that the CO2 comes out of solution more easily. Any discussion involving nitrogen rushing out is either in the context of a widget (where nitrogen gas is forced through the beer) or in the context of nitrogen being forced out of solution by a perforated disk or hard pour. Note in these explanations I’ve used the word “forced”. Rarely would I need to force CO2 out of solution.

I can’t say why 100% nitro isn’t used - maybe it is, I haven’t researched it. My guess is that you can have too much of something or maybe you need the CO2 to provide a level of protection against oxidation while you’re trying to get nitrogen into the beer - which does take longer.

We have rather strayed from the point of this thread though.

Strayed ? Yous would need a Sherpa and some mules to get back on track.

 

[Robin54]

I found the bubble size increased greatly when I put my glasses on

 

[Sadfield]

Strayed ? Yous would need a Sherpa and some mules to get back on track.

Pick them up on you way back from your date with Chippy, will you.

 

[foxy]

I am wondering now how the pour from the kegs with a bladder will be using a sparkler tap?
The beer is naturally carbonated in the bladder and forced out by air pressure on the bladder.
So using a sparkler tap instead of a regular keg tap could potentially give the pour of a beer engine.
I did see a video of UK pubs using these types of kegs but never took much notice of the pour.

 

[Twogunrocky]

Quick shmoogle and here's a chemistry professor's take on it....
Fizzics of Beer

 

[Bernie]

Carbonation, or Nitrogenation, and dispense seem like a very important part of the equation in answering the original question.

Despite the claims of bubble size between the two gases, I don't notice much difference between nitro keg and well served cask, pulled through a sparkler.

Carbonation, or Nitrogenation, and dispense seem like a very important part of the equation in answering the original question.

Despite the claims of bubble size between the two gases, I don't notice much difference between nitro keg and well served cask, pulled through a sparkler.

The nitrogen and the widget effectively do what a sparkler does by forcing the liquid through a narrow orifice to cream up the foam,

 

[Sadfield]

Yes. Widget, nitro with no widget, sparkler on cask, there all techniques to promote creaming.

Watching any video on YouTube demonstrating the perfect pour from cask, keg or bottle all appear to follow the same process. Vigour to promote creaming, combined with a fast pour allowing less time for disproportionation. The result is a tight head with small bubbles and also oxygen pickup. Leaving a beer that still contains dissolved co2, giving an effervescence when drunk.

 

[user 45890]

Quick shmoogle and here's a chemistry professor's take on it....
Fizzics of Beer

Interesting read.