I just finished my first batch, a Brooklyn Brew 1gal kit, and was unable to split the batch evenly over 8 bottles so I ended up with 7.5. When I went to taste the beers after two weeks in the bottles I received 2 very different flavors between a full bottle and the half bottle. What is the cause? and how can I prevent this issue in the future?

Additional information: I was using 22oz Grolsch bottles and was able to put in about 12oz into that bottle. Since I didn't have a capper I stayed in the same bottle. I did not individually sugar the bottles but placed the maple syrup(in lieu of sugar) directly into my pot. The flavor was more tart and flat compared to the others.

2 Answers 2


A few possible reasons come to mind:

  1. If you have added the same amount of sugar to each bottle (as opposed to adding directly to your bucket) then you have different "gravities" and depending on how much it's fermented, different flavour profiles.

  2. If you have left a large headspace in the bottle during the carbonation phase, you might find that the carbonation has not absorbed into the beer itself, rather into the headspace. CO2 has it's own flavour but carbonation affects mouthfeel and flavour too.

  3. When bottling that last beer, if you weren't able to get a full bottle's worth of beer, you likely got a fair bit of yeast and/or trub along with the beer. This will significantly affect flavour.

If you provide some detail on the different flavours (e.g. bready, bitter, tart, fuller) we could help figure out which is most likely. My money is on #3 though.

  • CO2 is flavorless on it own. But your point that different amounts of carbonation effects the flavor point is valid.
    – brewchez
    Commented Sep 27, 2012 at 21:31
  • co2 forms carbonic acid in the beer. compare carbonated water against still water and you'll see there is very much a taste from the carbonation.
    – mdma
    Commented Sep 28, 2012 at 6:55
  • I'm with @mdma on this one. It could be the carbonation or the carbonic acid, but force carb a bottle of tap water & compare. From wikipedia: "Carbon dioxide dissolved in water at a low concentration (0.2%–1.0%) creates carbonic acid (H2CO3),[2] which causes the water to have a slightly sour taste with a pH between 3 and 4" - so the pH could impact too. Commented Sep 28, 2012 at 7:50

The problem:

  • As C4H5As said, the half-full bottle may have been under-carbonated due to having so much headspace.
  • You also may have had more oxidation due having so much more air in the bottle initially. John Palmer has a list of Common Off-Flabors and says that oxidation causes "wet cardboard or sherry-like flavors".

The solution:

  • When I'm bottling, I try to avoid this problem by using a mix of 12oz and 22oz bottles. If you're using 12oz bottles and get to the end and realize you only have half a bottle left, carefully pour it into a 22oz bottle with one of your full 12oz bottles. Or if you're bottling in 22oz bottles, pour the half-empty last one into a 12oz bottle.

  • These problems can also both be avoided by force-carbonating in a keg and then flushing the bottles with CO2 before filling, but I assume that's way beyond you at this point.

(I prefer to use 22oz bottles in general, since they're more fun to share and require less work to clean and bottle. But they're harder to obtain.)

  • 2
    I usually just pour my partial into a glass and consider it a taster.
    – baka
    Commented Sep 28, 2012 at 17:00
  • @baka: I sometimes steal a taste, but if I'm bottle conditioning then the beer is warm and flat—not the tastiest.
    – Hank
    Commented Sep 29, 2012 at 17:14
  • I rack leftovers to a PET (plastic) soda bottle. I have fitted a tire filler stem to the cap. I squeeze the bottle so no air remains, then tighten the cap and use a bicycle tire CO2 filler to fill the headspace with CO2. It might sound complicated, but it's really simple and easy. Usually I don't use priming sugar in that one. Instead, I force carb it using the bike tire filler nd try it the next day!
    – Dale
    Commented Nov 11, 2012 at 15:02
  • By the way, my leftovers can be large, since I bottle into 6 liter bottles.
    – Dale
    Commented Nov 11, 2012 at 15:03

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