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Thread: Keg Shelf life

  1. #1
    Join Date
    Nov 2004
    Location
    Henley-on-Thames, England
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    204

    Keg Shelf life

    Hey guys,

    Is there any rule of thumb for shelf life of kegged product that is filtered, but not pasteurised? 30 days from kegging?

    Thanks,
    Jeff Rosenmeier (Rosie)
    Chairman of the Beer
    Lovibonds Brewery Ltd
    Henley-on-Thames, Englandshire
    W: www.lovibonds.com
    F: LovibondsBrewery
    T: @Lovibonds

  2. #2
    Join Date
    Oct 2002
    Location
    India
    Posts
    138
    Sterile filtered, 0.45 micron, we put a 60~90 day selflife on our keg beer.
    You need to do some QA/QC work and start by forcing some of your keg beer and ... more.
    Watch your filters!

  3. #3
    Join Date
    Oct 2002
    Location
    Tadcaster, Yorkshire, UK
    Posts
    1,056
    Not trying to get intoa an argument, but seems very high to me. 6 to 8 weeksabsolute max for pasteurised beer - let alone non pasteurised / sterile filtered beer. Cask beer, i.e. containing yeast - 4 to 6 weeks, depending on storage conditions - preferable the shorter time. Beer should be fresh (AB do have a point you know)

    Cheers
    dick

  4. #4
    Join Date
    Oct 2002
    Location
    India
    Posts
    138
    Agree with you on selling fresh beer. As for the shelf life, 60~90 days, that was the owners decision. Actually, seen breweries putting longer shelf live on there kegs.

    6-8 weeks may be norm but like I said force some kegs and see what you get.

  5. #5
    Join Date
    Nov 2003
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    99
    Excuse my ignorance, what do you mean by 'force'?

  6. #6
    Join Date
    Oct 2002
    Location
    India
    Posts
    138
    Forcing.
    We use to take samples of all packaging runs.
    Some of the samples we forced by storing them under refrigeration Temperatures for 24 hours, then ambient plus temperatures for 24 hours, repeating this process for as long as needed. This ages the beer over a short period of time. While doing this, we would do taste, biological test on a regular basis to determine the shelf life.

  7. #7
    Join Date
    Jul 2004
    Location
    Fort Worth
    Posts
    8

    Keg shelf life

    It is very interesting reading these posts, however I think it's important at that point to talk about shelf life.
    There are roughly 3 types of shelf life:
    Microbiological shelf life
    Chem./physical shelf life
    Taste stability.
    For microbiological shelf life you need either aseptic filtered beer (cold sterile filtered= for best beer quality) or flash pasteurized beer. Further a very well maintained keg line with excellent housekeeping. (Good CIP cycle ((internal for the kegs, external for beer lines)), sterile air/co2, and beer with a good immune system, by that I mean beer internal values that makes it hard for beer spoilers to grow. e.g. end fermented or almost end fermented beers, ph< 4.5 (not < 4.3 to much build up of carbonyls), BU > 25, photometric iodine <0.25 , excellent yeast management and so forth.
    If all the above is ensured you can have beer that lasts for more than a year.

    Chem/pysical shelf life: that means mostly collide turbidity, which is caused by protein, KH, polyphones and metal ions, O2. But also color, foam, BU and so forth.
    With all malt beers and German purity law it's tough to get this under control, but possible. Adjunct beers have some advantages, plus if you are producing outside the purity law you have numerous options more to get a better grip on that issue.
    But I would say with a balanced stabilization (protein side + polyphonies side), good quality malt, good process conditions and so forth you can also get over a year shelf life on that part.
    (This topic is of course more complicated, but this is meant be a brief overview)
    Taste stability: that is the toughest problem.
    There are several different mechanisms and reactions involved that cause taste (in)stability (O2, fatty acids, maillardreaction, oxidation of higher alcohols, carbonyls, caramelariasation of sugars and so forth) also a very complicated topic.
    The fact is however that after I would guess 4-6-8 weeks you are getting problems with taste stability in your beer.
    If you pull all the strings throughout production (O2 optimized...) and use good raw products and have sophisticated equipment you can achieve maybe more then 2 month shelf life. (Taste stability) that is.
    After your beer leaves the brewery, then of course you have to consider all the external factors like: temperature, movement and time that can harm your beer even more and/or quicker.
    There is a lot more to say about that topic, but those are my 2 cents for now,
    Regards
    Peter Boettcher
    Abita Springs, LA

  8. #8
    Join Date
    Mar 2003
    Location
    Nashville
    Posts
    670
    Peter,

    Can you explain the effect of beer pH on carbonyls that you mentioned?

    Cheers,

    Linus Hall
    Yazoo Brewing
    Nashville, TN

  9. #9
    Join Date
    Jul 2004
    Location
    Fort Worth
    Posts
    8

    Keg shelf life

    Hello IHall,
    I try to,
    Although I can not draw you the exact chem. formula/reaction for that one, (I have to look this up)
    I know that Carbonyls (Aldehydes, Ketones) are influenced by the ph, temp, O2, and have a negative effect on taste stability.

    I think below ph 4.4 the build up of Carbonyls is re-enforced.

    Ph - 4.5 = good for taste stability
    Ph - 4.2 - 4.3 = good for Diacetyl reduction, taste and colloidal shelf life.

    For further explanations I have to dig up my books.
    Regards
    Peter

  10. #10
    Join Date
    Aug 2004
    Location
    Chico, CA, U.S.A.
    Posts
    28
    Peter - Excellent post! Kudos to you.

    Bob August
    Majestic Packaging Solutions
    www.majesticpackaging.com

  11. #11
    Join Date
    Nov 2004
    Location
    Henley-on-Thames, England
    Posts
    204
    Thanks for the valuable feedback guys. I guess I was thinking along the lines of taste stability - or maybe just how many days you guys are willing to put your name against?

    Cheers,

    Rosie

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