How much carbonation is too much?

Discussion in 'Home Bar' started by mewanderinghome, Aug 22, 2020.

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  1. mewanderinghome

    mewanderinghome Initiate (0) Dec 14, 2010 Arizona

    I got a keg of Monk's Cafe Flemish Sour that tastes nothing like either the bottle, or the few times I've had it on draft elsewhere. Since Belgians can be all over the place in carbonation, I asked the brewer what volume of co2 they keg at, and he replied "4.2 gramm". Presuming weight of co2 instead of volume, that equates to really very low pressure, unusual for a Belgian. But because I wasn't sure about all of the calcs, I just started really low (6 psi at 38F) and kept dialing in more pressure until the co2 bubbles in the line disappeared, which did happen very low at 8psi. However, the taste has a very off flavor- almost a petroleum-like aftertaste, of all things. I had a new stainless Sankey coupler on it that I'd only rinsed, so I took that off to soak it overnight in vinegar and water thinking maybe the rubber seals were lubed with petroleum jelly or something. And while that may have helped a tiny bit, there was still much of the same very noticeable off taste. So I was thinking that maybe this very 'live' beer sat pasteurized and dead for far too long during Covid, and I got an old, not very good keg. It took a ton of work to get this keg (no joke 9 months of pressuring distributers & the importer, driving several hours, and paying a lot more than it cost last fall when I first inquired about pricing), so I didn't want to give up on it just yet.

    Even though the bubbles in the line disappeared at 8psi, I noticed the head had been dissipating, so I thought maybe a bit more pressure, and have been gradually dialing in more co2 (currently at 10.5). As I go higher, the flavor seems to be getting closer to the bottle (I have some bottles I'm doing comps with). So I think that may have been the issue, but I'm surprised carbonation can affect taste THAT much. It still isn't as good as the bottle, so I'm tempted to go higher. But what I do read about carbonation and flavor seems to emphasize that too much carbonation can hurt flavor, and I can't find anything about too little carbonation hurting flavor.

    My question is absent volume information, how do others determine if carbonation is too high? Flavor? Foam? My beer line is currently quite long and slow to pour so I'm not even close to too much foam (I actually center-pour and even agitate it a little while pouring to get closer to matching bottle head, but the bubbles are smaller out of the tap and it's a much-less 'lacy' foam). Once I get carb level correct, I'll cut the line length a bit at a time until I get the proper head from a pour.
     
    #1 mewanderinghome, Aug 22, 2020
  2. billandsuz

    billandsuz Pooh-Bah (2,097) Sep 1, 2004 New York
    Pooh-Bah

    Carbon dioxide is an acidic gas, and it is typically described as tasteless, odorless and colorless. When it is dissolved in water (or beer) is forms carbonic acid. That does have taste, and we perceive the flavor as sour.

    As the gas bubbles rise to the surface they carry with them all of the compounds in the beer, so we also get a good deal of aroma with the addition of CO2.

    The opposite is also true.
    Less dissolved CO2 means less sour flavor (that can also be perceived as more sweet flavor).
    Less dissolved CO2 means less aroma.

    So the presence of CO2 is very important.

    Determining the proper level of dissolved CO2 in a mass produced beer should be easy, just call the distributor and ask. Of course it's not that easy. Even experienced brewers are sometimes at a loss when asked. They will tell you something like "11 psi at 38 degrees" which is just not the answer.

    I suggest that you calculate the applied pressure based on the beer style guidelines.
    Unfortunately, many, most - imported specialty European kegs do not really shine. Bottle is usually better. Double for kegs that have otherwise bottle conditioned beer. No comparison.

    Cheers
     
    #2 billandsuz, Aug 24, 2020
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