Feeding oxygen to harvested yeast in a brink

[mattbk]

We have recently began using a yeast brink that uses a pump for mixing. We've found that prolonged continuous use of the pump, even set at low speeds, is damaging to the yeast viability. We are likely going to put in a timer that will pulse the pump on some frequency for a short amount of time to keep the yeast moving but not subject it to continuous stress. We were also wondering about gas. Does harvested yeast, as stored in a chilled brink, need oxygen to keep the viability higher? Our supplier recommended this but we could not find any resources that suggest this, or know of any theoretical reason why yeast that has no food source and stored at a low temperature would need oxygen. We have a 10 bbl conical brink used to store yeast harvested from 60bbl FVs. Thanks.

[dick murton]

If you oxygenate yeast, it will use up its glycogen resources whilst it is in storage, and the general wisdom of those who carry out the analysis of these sorts of things state it will then not perform so well in FV. If you oxygenate just before pitching then you really have no idea how much has been taken up by the yeast, and apparently it is not consistent, so you are better off oxygenating the wort. Simply keep the yeast cold - 2 to 4 deg C and agitate periodically if you have a high speed agitator, or continuously if you have a low speed, low shear agitator - just fast enough to mix, keep the temperature consistent, and stop it settling on the cooling jackets / cooling area which will inhibit heat transfer. Max storage time ideally less than 3 days.