Prevention of oxidation during packaging

John C

John C

South Jersey FC Member
There is probably no off flavor comment i see more during competition than oxidation (carboard flavor for whatever that means). It is a comment that hits me endlessly and a characteristic that I honestly can't detect in my beer. Since it first appeared a couple of years ago in the GSB contest, I have completely changed my packing approach. Now I do the following:

  1. Fill the keg completely with water (for my next batch) /sanitizer and blow it out with CO2. I then have a sealed keg of nothing but CO2
  2. Close transfer of fermented beer from my conical fermenter with both lines purged with CO2 first. Fill ine is the out line for bottom fill to the keg.
  3. After carbonation and generally no less than 10 days to verify target carbonation levels, I will bottle 6-8 bottles using a Northern Brewer Last Straw beer gun which has CO2 lance to purge the bottles (2-3 second burst at 10psi) and a spring release for bottom filling with minimum foam or turbulence. Bottles are filled until foam overflows. Capping is done immediately. Caps have O2 scavenger liners.
I submit only the middle bottles and assure they have the proper fill level. The bottles are stored in the refrigerator until submitted. Even with all that, in the last competition (MM Summer Vacation), my German Pils was rated at 17 with both judges noting "heavy oxidation overwhelming all other characteristics". I can even imagine what else I could do or where O2 could have gotten in.

Researching this a bit more on line I came across this video that I think is worth watching.


It was an experiement that looked at 4 different packing strategies on an IPA to check the impact on oxidation. The 2 controls were the original beer in the keg and a bottle 2/3 filled with no CO2 purging and shook to dissolve any O2 in the beer. The conclusion: Color change (darkening), but except for the unpurged bottle, no detectable flavor change. The color change on the 2/3 fill was very noticeable. The other 4 bottles were only barely noticeable against the sample from the keg. Because he used PET bottles which are known to be a poor O2 barrier, I can understand how even the heavily purged bottles could pick up O2, but to the brewer making the video, it was not enough to detect in the beer.

Would love any feedback on this.
 
Your process sounds solid John. Seems to be you are following all of the best process with your packaging. Maybe a problem with your capper? Which type do you use? Maybe not sealing. I would also suggest trying one of the beers bottled at the same time as your entries on or about the same day as the judging is scheduled to take place.
 
So after reading I would suggest not using 10psi on your purge. I would lower it to 2-3 psi and purge for about 5-10 seconds. A high psi burst actually disrupts the air and instead of getting a blanket of heavy CO2, you are blasting it in there mixing with the air in there. A lower pressure but a little longer of a purge will give you a layer of CO2 that pushes the lighter air up and out rather than a high blast mixing of the CO2 with the air. When I package with the beer gun I would always use 2psi and go 5-10 seconds of purge before filling.

While oxygen is very commonly introduced during packaging, it can be introduced during the end stages of making beer. Dry hopping, adjuncting... anytime you open your fermenter/airlock you are giving oxygen an opportunity to get in. Once oxygen is introduced even a tiny amount can start to give your beer that cardboard flavor. For one of many reasons, pressure fermenting is one way to eliminate that. Closed system the entire process. Pro breweries usually have a slow flow of CO2 through their carb stones when the Fermenter is open to add Adjuncts or hops ...as the influx of CO2 keeps positive pressure to keep oxygen out of the Fermenter when adding anything to the beer.
 
Good suggestions here and will implement them during next time packaging. As for dry hopping with fermenter additions, that looks to be impossible to do without introducing some O2 either through the opened fermenter or from the hops themselves.

I am considering trying pressure fermenting, but even there i wonder how much O2 is left over after fermenting. It has to diffuse through the headspace in some way without agitation and by definition there has to be some level left.
 
John C said:
Good suggestions here and will implement them during next time packaging. As for dry hopping with fermenter additions, that looks to be impossible to do without introducing some O2 either through the opened fermenter or from the hops themselves.

I am considering trying pressure fermenting, but even there i wonder how much O2 is left over after fermenting. It has to diffuse through the headspace in some way without agitation and by definition there has to be some level left.
Click to expand...
Oxygen in the Fermenter pre fermentation will get used by the yeast. Even dry yeast when that doesn't need oxygenated wort will used oxygen. But remember fermentation starts slowly and the builds up....so the co2 from fermentation builds onntop of the wort and is heavier than o2 and atmospheric air....so fermentation natural pushes all outside air out first. Even with pressure Fermentation I'll usually wait to close off the spunding valve til fermentation becomes active
 
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