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  • Wild yeast Problem, Help!

    Hi there.
    This is my first thread because I always see this forum to get information that I need, but this time I can't reach a solution and that's why I'm here.

    Last batch we detected a significant change of FG from 1.007 to 1.004 g/L within 3 days just before it was ready to be bottled. We had to dump it.

    Since that point, every batch we have made is contaminated with this microorganism. We plated a sample of our beer and seen under a microscope it looks like a wild yeast. ( Picture 1)

    Our current CIP is as follows:
    1. Water rinse
    2. Caustic at 2% at 60°C
    3. Water rinse until reaching a pH between 7-8
    4. Acid wash with a mix of phosporic and nitric acid (formulated product ). ( this step we do it only once a month )
    5. Water rinse acids reaching until pH 7-8
    6. Sanitize with peracetic acid at 0.035%

    And after this we still have the contamination problem. Fortunatly a beer we make it's with dryhopping and off flavors disappear.

    We have the following off-flavors:
    1. Phenolic (like band aid)
    2. Diacetyl
    3. Fusel alcohol

    Another organoleptic problem:

    1. Smells like a fermented fruit.
    2. If you know a latinamerican drink called "Tepache" ... well, smells just like this.

    Photos:

    Click image for larger version

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    Click image for larger version

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    NOTES:

    We think contamination comes from tanks because generally during and after fermentation it smells and tastes well. When we filter beer, the hoses and pump we use have just been used for cleaning the tank.

    It is always is the same wild yeast, with same characteristics.

    Loss of FG only occured when the beer has been sitting in the tank for days.

    We think we have Silica adhered to the tank and that's the contamination problem ( If you pass your finger on it, you can feel some invisible film that comes with the finger. For a reference, feels like dry hair gel )

  • #2
    Swab/plate your yeast, heat exchanger, oxygenation/aeration stone, hoses, and fv's after CIP/sanitizing. Replace any cold-side permeable materials like gaskets. Also make sure your pump flow rate is sufficient for an effective CIP and that your spray ball is functioning properly. I prefer to use caustic at 80 - 82C.
    Last edited by ipaguy; 04-27-2017, 05:41 PM.

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    • #3
      Are you using a gas exchange line between the brite and the fermenter? If so, how often is that cleaned/sanitized?

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      • #4
        Hoses are always my first suspect.

        Hose ends can get loose, allowing critters to hide between the barb and the hose. Internally-expanded hose end fittings nearly eliminate this source of contamination. Barb fittings with hose clamps/Band-its nearly guarantee this as a problem.

        Hose linings can crack and/or separate from the hose body. This can be a very small blister inside the hose that is only inflated under flow. These problems are very difficult to isolate, as the blister is nearly invisible when it isn't inflated. One symptom is reduction of flow with increased pump speed, when the flow should be increasing, instead. The only way to insure your hoses don't have internal problems is very careful visual inspection. I use a cheap endoscope I purchased online. It has a 25' lead so I can inspect the hose linings using my laptop.

        Storing a hose by hanging it over something with too small a radius is a great way to get the liner separating from the hose. Brewery hoses have large minimum bends. Using the best hoses you can buy and being very careful to follow best practices, expect hoses to last around 3 years max.

        For silicate deposits in your brew vessels, consider another caustic wash after your acid wash. Organics, calcium deposits, and silicate deposits make for a challenging cleaning regime. First caustic wash removes the organics, allowing an acid wash to remove the calcite. A final caustic wash can now get to the silicates that have been exposed by the acid. This should only have to be done occasionally.
        Last edited by TGTimm; 04-28-2017, 09:46 AM.
        Timm Turrentine

        Brewerywright,
        Terminal Gravity Brewing,
        Enterprise. Oregon.

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        • #5
          You might also want to consider including an oxidative cleaning additive with your caustic cycle...something like Lerasept O. Consult your local chemical supplier.

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          • #6
            Originally posted by ipaguy View Post
            Swab/plate your yeast, heat exchanger, oxygenation/aeration stone, hoses, and fv's after CIP/sanitizing. Replace any cold-side permeable materials like gaskets. Also make sure your pump flow rate is sufficient for an effective CIP and that your spray ball is functioning properly. I prefer to use caustic at 80 - 82C.
            In fact I have a 1 hp bomb.I'm thincking about to change it for a 2 hp bomb.

            I'l try caustic at 80°C

            Thank you!

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            • #7
              brand new yeast pitches each time?

              how do you pitch, thru the manway or a brink.

              is there a visual inspection after the acid before sanitizing of the inside of the ferementor and her peripherals with a flashlight?

              anything that can be taken apart should be taken apart every time even if it's a small hassle like with perlick zwickels
              I hope I encouraged you!

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