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Dried Yeast Sample Contaminated

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  • Dried Yeast Sample Contaminated

    Hello Guys!

    We did some NBB-B testing for common spoiling bacteria in a dried sample of a famous yeast and the results were positive!

    I have read that there are some tiny amounts of wild yeasts according to the manufacturer specifications.

    My question is..

    Is this something common in the brewing industry?

    Should I use this yeast?

  • #2
    Originally posted by Ale_Guy View Post
    Hello Guys!

    We did some NBB-B testing for common spoiling bacteria in a dried sample of a famous yeast and the results were positive!

    I have read that there are some tiny amounts of wild yeasts according to the manufacturer specifications.

    My question is..

    Is this something common in the brewing industry?

    Should I use this yeast?
    Hi,

    We saw positive NBB-B results all the time:
    - paa in 30l bucket
    - pasteurise with 80C water
    - let it cool down
    - take atp reading from bucket which was 0 from time to time we got a 1.
    - rehydrate dry yeast
    - yeast sample incubated on lysine agar and nbb b tube

    Lysine was always 0cfu but nbb b was positive most of the time.

    I talked to Doehler about this and they said that the slight contamination in dry yeast might not come to the surface in a brewery fermentation but in a lab environment and an enrichment medium designed to grow beer spoilers, this one bacteria cell in a gram of dry yeast would show.

    Since we have ccts and can harvest (started with a liquid culture) we have not seen any colour change in our nbb b and we are on our 8th generation.

    With dry yeast we fresh pitched every time but knowing about this contamination I would not repitch dry yeast more than a few times. I know a lot of brewers do but I would not.

    I hope that helps.

    Edit: we never had infection issues with dry yeast

    Matthias
    Last edited by MatthiasS; 12-24-2017, 04:29 AM.

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