I’m not sure if I’m using the proper term, but what parameters affect the fineness/coarseness of bubbles in beer? I’ve noticed a lot of the beers at my homebrew club meetings have very coarse bubbles, like in soda-pop. My beers tend to have much smaller bubbles, more like foam. Is bubble size an indicator of other issues with the beer? I’m guessing it’s related to body or protein levels, but I dunno.
I’d argue it’s more time and balanced system.
It always seems to me that younger hard shook beers served through cobra lines are big, gassy and eventually settle.
I think most of the beers are bottle-carbed, though a few are kegged. Does that make a difference, or does it still take time?
I agree with Drew. The more time you give the CO2 to go into solution, the finer the bubbles will be.
I always get more stable, small bubbles out of a keg force carbed over a 2-3 week period than a quickly carbed keg.
As to bottle-carbed beers, I would expect the bubbles to be finer if the bottles are refrigerated for several days or more before serving as opposed to just overnight. If you ever make sparkling water by kegging, you can taste the water developing bite over several days even after disconnecting CO2 supply as CO2 becomes carbonic acid.
isn’t bubble size more a function of nucleation site geometry? If co2 is disolved in a liquid it’s disolved. I don’t see how the method of disolution or the length of time it has been disolved would have an effect. Not saying it doesn’t just that I don’t understand if it does. I can see newer beer having more suspended particulate, or perhaps larger suspended particulate is more accurate, and this would result in larger bubbles as more surface area on the particles would result in more co2 glomming on to that particle = larger bubble. while an older more well aged beer would only have very small particles still in suspension thus less surface area = less co2 glomming = smaller bubbles.
I guess this is testable if one had a filter with varying grades of media. take the same beer, filter at say (these sizes are coming straight out of my… well I don’t know if the are accurate) 5 microns and then a portion at 2 microns… a portion at 0.5 microns. carb each portion up for the same amount of time (have to force carb to really test) and compare bubble sizes.
Scientifically, CO2 dissolves into water as as dissolved CO2 initially before becoming H2CO3 or HCO3-. “The hydration of CO2 and dehydration of H2CO3 are surprisingly slow reactions” per my analytical chemistry textbook. Empirically, I’ve observed changes in flavor from carbonating water over several days as the amount of carbonic acid increases.
I don’t believe that nucleation sites are necessary for effervescence caused by a sudden release of pressure. The only nucleation sites that I’ve observed are scratches in glassware. Work does not permit me from observing a beer at this moment.
I agree with kramerog, injecting CO2 into an aqueous solution initially produces an ‘aqueous CO2’ product (CO2 + H2O = CO2aq). It takes time for that aqueous CO2 to hydrate into its end form: carbonic acid (H2CO3). This is a slow reaction due to the change in the molecular configuration that the molecule has to undergo. That change is temperature dependent.
In a way, the temperature effects for CO2 solution are counter to each other. You want low temperature to improve the solubility of CO2 in an aqueous solution, but low temperature delays the ultimate hydration of the CO2 into carbonic acid.
I wonder if particulates play a part in the overall nucleation and release of gas bubbles? Morticaixavier raises an interesting issue, but it appears that the primary change from coarse to fine bubbles is the CO2 hydration into carbonic acid.
I wonder if higher temps for bottling conditioning, like Belgian brewers employ, help increase the hydration rate of the CO2? Or does the CO2 produced fill up the headspace in the bottle first, and then have to diffuse through the solution?
This should be easy to test for anyone who bottle carbs. Pull two out of the fridge and roll one on its side to get the yeast in suspension. I might have to try this tonight, provided I have two from the same batch in the fridge.
on an only slightly related note can any of you science types explain why shaking up a sealed bottle of carbonated beverage causes it to release disolved co2 so much faster then the container is opened?
That one I always understood to be about nucleation sites. Shaking it up puts bubbles from the headspace into solution, which then become runaway nucleation sites.
Would the pH affect the hydration of carbonic acid? I bottled a Flanders Red (pH 3.6) a week ago, with a healthy dose of fresh yeast. It’s just about fully carbed now, and the bubbles are very fine.
Would carbonating to higher levels affect the fineness? These beers are about 4-4.5 vol.
I hate when I suddenly get something…
" injecting CO2 into an aqueous solution initially produces an ‘aqueous CO2’ product (CO2 + H2O = CO2aq). It takes time for that aqueous CO2 to hydrate into its end form: carbonic acid (H2CO3). "
Duh I understand this now
I don’t think the formation of carbonic acid has much to do with this. While the formation of carbonic acid is a slow reaction, the reverse reaction is quite fast. This means that CO2 will be available quickly whether its already CO2 or still in its hydrated H2CO3 form. Further more, the amount of CO2 compared to H2CO3 is quite large. When equilibrium is reached, there is about 600 times the amount of CO2 compared to the amount of carbonic acid. As a result, the carbonic acid should play only a minor role.
Kai