Pasteurization Experiment

[fastricky]

I want to see what effect pasteurization truly has on beer, as well as how it will effect shelf life.

Here's what I intend to do:

- Take a lager that has been fully fermented in a corny keg and attach one end of thermoplastic tubing to the out post. The tubing will be coiled in a bucket ala an immersion chiller (I'm using @ 12' of tubing). The end of this tubing will get attached to the out post of another receiving keg. (Dang, just realized I'll need a stainless steel ball lock disconnect for the receiving keg...)

- I'll fill the bucket with boiling water, then push the beer from one keg to the other with low psi to make sure the beer gets heated hopefully in the neighborhood of 160 - 170 degrees while traveling thru the tubing.

- The second keg will be sitting in an ice bath and that will be replenished with ice as necessary to aid in cooling the pasteurized beer quickly.

- Once half the keg is thru, I'll stop the flow and immediately put the newly filled keg into the freezer.

- The remaining half left in the original keg that was not pasteurized will be filtered and bottled the usual way I do...

Should be a cool comparison. Any thoughts on my process?

 

[fastricky]

Oh, one additional benefit of the pasteurization might be that the beer will clear very quickly due to no living yeast... that's my assumption anyways.

 

[wyzazz]

Sounds like a winner, I'm interested in the results!

 

[Mischief_Brewing]

Typically, the pasteurization process requires 160+ degrees for 15-20 seconds. Think your process will keep it at/above that temp for that long? I'm trying to imaging how it will work but coming up empty on the length of time it'll be at the higher temps..

 

[fastricky]

I've got an inline thermometer installed after the immersion coil to monitor the temp, and I'll control the rate of flow to approximate how long the beer stays at 160 degrees.

That's the plan anyways! It'll be another week before the beer is done lagering, at which point I think I'll filter it, then once it warms back up to room temp, I'll try this pasteurization technique.

I'll keep y'all posted on how it goes!

 

[fastricky]

Well, the deed is done and the results are in.

I split a corny so that I pasteurized half and kept the original half to compare against.

As far as flavor and aroma are concerned, the difference is negligible. I almost think I'm imagining the non-pasteurized beer to be slightly more aromatic, but I really couldn't say it is true.

Suffice to say, in the months to come if the pasteurized version (once bottled) is far more stable, it's a process I'll be doing much more often.

Here's a quick look at the machinery...

Overall view - the beer is pushed from the corny into a stainless steel immersion chiller that is in 9 gallons of boiling water (gas kept on as the flowing beer knocks down the temp of the hot water pretty quick). I control the flow/temp with the CO2 pressure and a valve coming out of the chiller.

From there it goes into the counterflow chiller where it's knocked back down to room temp and flows into the 2nd keg.

 

[fastricky]

Some additional views...

 

[prosper]

You might also consider putting a filter in the line somewere for sparkling crystal clear pastuerized beer, without any organic debris (dead yeast) decaying in your beer

 

[fastricky]

It's funny, the beer was already filtered (thru a sterile filter) and yet, you're right, there still is some organic debris settling in the bottom of the bottles... weird!

 

[samc]

Interesting experiment but I don't understand why you want to turn living homebrew into dead brew, just drink faster if it is not stable enough for you. Or keep it at near freezing temps to preserve it longer.

 

[fastricky]

I brew a lot! So I really can't drink it all immediately... and really don't want to anyway. I wish I had an extra fridge to keep the beer in, but that's not an option in a NYC condo.

 

[GRHunter]

Holy sheep dip! That is one complicated looking setup.

 

[SpanishCastleAle]

Just a thought: My way of getting crystal clear beer (in bottles) is to put the beer in a keg, carb it, and drink half of it from the keg. Then bottle the last half from the keg. Since corny kegs pull from the bottom, when you drink that first half from the keg you're drinking the 'bottom half' which is all the cloudiest beer and stuff that settled from the 'top half' of the keg. By the time you get to the last half it's crystal clear. Not just clear, crystal clear. This also allows you to dial in the carb level just right before bottling (not that that's a big problem but w/e).

 

[greenbirds]

Interesting experiment, your methods seem valid. If you couldn't maintain 165 F for 15 seconds, you could try another round at 180 or so. I'm too lazy to run the math, but since the thermal death/inactivation time-temp relationship is exponential, 180 should need only a few seconds. Or 150 for about half an hour

You should try to report back periodically how it tastes over time versus the live bottles. Room temp storage vs refrigerated would be interesting, too.

Also, you said it was a lager; was it a hoppy pils type beer or a malty like a dunkel? I would imagine the dunkel would stand up better to pasteurization.

 

[fastricky]

The process wasn't to get the beer crystal clear (it was already post filtration) it was to see if bottle stability was improved. I'll certainly report back on that in the months to come...

The beer was a hoppy pilsner btw!

 

[Zen_Brew]

Great experiment. I was recently envisioning something similiar myself using 2 immersion chillers. One in a cold bath, and one in boiling water. My interest was not in stable bottle storage however. I was considering methods to halt fermentation with residual sugars left in the batch for something like a sweet fruit lambic without having to backsweeten.

 

[fastricky]

Yeah, I'll be doing that too to get the yeast to stop doing their thing when making fruit beer. It'll work perfectly.

 

[Cpt_Kirks]

I wonder how well this would work with infected beer? When I have an acetobacter infection, the beer is not too bad at first, but quickly turns to vinegar.

If caught very early, could pasteurization kill the infection and save the batch?

 

[fastricky]

Absolutely.