Lagering process specifics

[Goose]

Nothing wrong with the dried yeast, must be something procedural you are doing(or failing to do) to stress the yeast. Should be an easy fix though, more oxygen, more yeast, rehydrate yeast (flame suit on), pitching temp, fermenting temp, nutrient levels etc etc etc.

well I'd love to know too. For oxygenation I pump inline via an airstone during transfer to fermenter. I use the correct amount of yeast nutrient added last 10 minutes of the boil. For the 45l last batch, I rehydrated 4 x 12g pckts in previously boiled water at 23 deg C and pitched into wort at 14 deg c, fermented at 11. It seemed to go well enough. Raised temp slowly to 19 deg C after gravity fell below 1.020 and held till FG reached, then crash chilled. Could taste no diacetyl in beer prior to racking, but it appeared around 2 weeks after racking to keg. I know this because I carbonate at dispensing pressure (12psi) and sneak a taste regularly.

And yes I did try the AAS test prior by heating up a sample in a water bath. Seemed fine.

I have since re-used the yeast cake for 2 subsequent batches... same damn issue. A side by side batch made with Danish lager and a 5 litre starter did not have that issue. Identical recipe and process. Has to be a yeast specific problem.

 

[manticle]

Lines are clean?

 

[Goose]

Lines are clean?

probably not as rigorous as some but if it were bacterial I don't think the active yeast addition would correct it, and it doesn't happen with the Danish lager yeast so fairly confident its not the lines.. but thanks.

 

[GalBrew]

If you have done a forced diacetyl test and got nothing, your beer is clean at kegging and your lines are clean then there has to be a contamination in your Danish yeast cake that only gets noticeable levels of diacetyl once the yeast slow down.....or am I missing something??

 

[Goose]

If you have done a forced diacetyl test and got nothing, your beer is clean at kegging and your lines are clean then there has to be a contamination in your Danish yeast cake that only gets noticeable levels of diacetyl once the yeast slow down.....or am I missing something??

thaks bud, actually I ran side by side liquid vs dry, wyeast danish vs dried s189 respectively. It was the latter that threw diacetyl even after batch 5. But correctable using rehydrated dried yeast.

I guess point of my post was to show that you can correct a diacetyl problem post racking by adding active yeast from packets... recognising always that prevention is better than cure.