Dried Yeast Sample Contaminated

[Ale_Guy]

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?

[MatthiasS]

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