Jocky wrote: ↑Sat Nov 20, 2021 4:37 pm
... If you’re pitching liquid yeast (aside from kviek yeasts) or re pitching yeast from a previous batch then aeration is essential. Dry yeast does not need aeration, just sprinkle it on wort or rehydrate it in sterile water.
That is wrong! However, if you're not confident how well your starter performed, it's best to assume it is "right".
Yeast grown in a good air supply (constantly stirred and stoppered with a very gas porous plug - like the specially created foam stoppers or cotton wool at a push) will store any surplus sterols they create for later, just like yeast being prepared for drying.
But you do have to be very confident with your yeast starters. The following is a recent build I did, but I got too impatient settling it out and lost about 20% of the created yeast cells (I didn't actually "lose" them, I suspected something was amiss and settled out the remaining yeast for another 18 hours before adding it to the starter for the next brew - same yeast, in fact the second starter was created from the over build planned in the first):
- 1889 Morrell's Bitter IV.JPG (38.95 KiB) Viewed 1603 times
Fortunately this was in the 70L fermenter and therefore oxygenated. But fermentation was slow to start and overall very sedate (6 days, for me that is sedate). The other very similar beer was in the 25L fermenter and NOT oxygenated and the starter barely decanted (plus it received the "lost" cells from the first beer):
- 1880 Simond's Bitter VI.JPG (37.49 KiB) Viewed 1603 times
Traces look rougher because it comes from a normal Tilt hydrometer (the first was from a Tilt PRO
). Scales about the same. It starts quicker and finishes much quicker (within 3 days). It finishes "high" because I was manipulating the mash and fermentation to make that happen. Remember, the second brew was NOT oxygenated/aerated.