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  • 1.  Metallic Off Flavor Post Filter

    This message was posted by a user wishing to remain anonymous
    Posted 02-02-2023 11:45
    This message was posted by a user wishing to remain anonymous

    Hi MBAA Community! We recently started filtering our lagers with a lenticular filter. We have a 16" x 4 housing from Scott Labs and use 4 x K250 SupraDisc cartridges from Pall. Both our Pilsner and Light American Lager have picked up a small amount of metallic off flavor after having gone thru the filter. I've never experienced this using the same equipment/cartridges elsewhere. We bought the housing used and as I write this I am wondering if perhaps the bell needs to be repassivated. This plausible? Any other ideas? Thanks everyone


  • 2.  RE: Metallic Off Flavor Post Filter

    Posted 02-02-2023 20:17
    Without the passive layer in between the beer and the metal, off-flavors are definitely possible and common. Especially in lighter beers as those mentioned, the metallic off-flavor could be easier detected than in heavier beers.

    I would recommend running a strong Nitric Acid passivation through the filter housing and see if the problem goes away.  Also, are you packing the filter in any chemical by chance? There could be another possible source.

    Cheers,

    ------------------------------
    Dirk Loeffler
    Loeffler Hygiene & Safety Solutions
    (404) 229-7583
    loeffler.dirk@loefflerhygiene.com
    ------------------------------

    Original Message


  • 3.  RE: Metallic Off Flavor Post Filter

    Posted 02-03-2023 12:22
    I would agree that a re-passivation is probably your best bet. If lenticular filtration is new to you, make sure to remove the cartridges before running a nitric cycle! 

    A few other things come to mind that could be the issue if the passivation doesn't correct it. 
    1. Was the problem really evident on pad generation 1 and then diminished over time? If so, you probably need to extend your initial flushing as there is a distinct pad taint that we find to be papery, but I could see it flagging slightly metallic. Pall recommends a flow rate of 15bbl/h per module for 8+ minutes. We also do a smell and taste check of the outlet water. 
    2. Have you noticed any off-flavors in your process water - particularly where you connect to the filter? The pads can hold a lot of liquid and you may have some process contamination, especially depending on your batch size. The same would apply if you are using a chemical storage solution between filters. 
    3. I believe the K250 modules are DE based. There is some evidence that DE can have high concentrations of heavy metals dependent on source. The FDA was (is?) even investigating the residual content remaining in beer as a possible contaminant. This might be a long shot, but worth a discussion with your Pall supplier/rep. 
    Ken Belau at Pall (MBAA Member) is an excellent resource on lenticular filtration and I would reach out to him. 

    --
    CAMPBELL MORRISSY | HEAD BREWER
    pFriem Family Brewers
    p | 201-704-6304
    pr | he/him

    707 Portway Ave Ste 101
    Hood River, OR 97031



    Original Message


  • 4.  RE: Metallic Off Flavor Post Filter

    Posted 02-06-2023 12:50
    Hi,

    Another passivation might help, but if the equipment was used for a while by another brewer, it is probably pretty well pickled.

    But I like Cambell's idea #3 and don't think it's a "long shot".  Diatomaceous earth (kieselgur) and perlite found in the pads might contain small amounts of manganese or iron.  Beer filtered through these pads could pick up a metallic flavor. In a brewery in which I worked long ago (and far away) we received a bad load (railroad car) of DE with a high iron content that did indeed create a metallic flavor in our light lager. Have the beer analyzed for iron and manganese content. Or better yet, have the pads analyzed as well.  Also, try a different lot of pads and see what happens.

    Hope this helps.

    Cheers,

    ------------------------------
    Kenneth Jennings
    Brewing Science Services, llc
    Portsmouth NH
    (603) 812-7332
    ------------------------------

    Original Message


  • 5.  RE: Metallic Off Flavor Post Filter

    Posted 02-07-2023 14:36
    Hello Fellow Brewer,

    Look for a local lab that can test for metals like iron and copper. Pull samples from inlet and outlet of filter at start up. If you have a metal pick up there, it is typically most egregious in first beer through filter. Normally, a contract lab can test for metals for a nominal fee.

    You need to know the actual metal content in your beer to make sure this metallic taste is actually iron. Tongue receptors can be fooled! That is, other compound (fatty acids, for example) can "ping" the same receptors tricking you into believing you are tasting iron.

    If it is iron, it might be from earlier in your process. Other than DE, the most likely cause is yeast autolysis (in that case you might find a noticeable level of zinc in your final beer) or a change in Brewhall operation - that is, excessive trub carryover or change in mash/wort pH (iron solubility increases at lower pH). If you recently lowered mash or wort pH you may have inadvertently increased your wort iron carryover.

    Good Luck,
    Dan Carey
    New Glarus Brewing Company

    ------------------------------
    Daniel Carey
    Brewmaster
    New Glarus Brewing Company
    New Glarus WI
    (608) 527-5850
    ------------------------------

    Original Message


  • 6.  RE: Metallic Off Flavor Post Filter

    Posted 02-07-2023 20:02
    Re-passivation is definitely worth a try especially if it's a used vessel but I would also look into non-DE cartridges. There are lenticulars, such as BECODISC R+, which offer advance high purity cellulose material with no addition of minerals, including DE. Eliminating any minerals in your system should remove the metallic off-flavors, if in fact, it is because of the DE and other minerals in your system. Other advantages to cellulose based lenticulars are a) increase service life , b) optimize flow distribution maximizing filter utlization and c) no additional backflushing kits required.

    ------------------------------
    Aldo Guarneri
    Regional Sales Manager
    Eaton Corporation
    Schomberg ON
    (416) 577-0402
    ------------------------------

    Original Message


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