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Author Topic: What size erlenmeyer flask do you use?  (Read 2105 times)

Offline ynotbrusum

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Re: What size erlenmeyer flask do you use?
« Reply #15 on: February 27, 2022, 09:44:43 am »
I so rarely make a starter anymore…I just repitch, often directly from primary to primary.  It takes some coordinating brew days, but really makes the availability of super fresh yeast a certainty.  As to Ehrlenmeyer flasks, I used 2 liter size flasks most frequently before moving on to gallon jugs and SNS approach to starters…but I now directly repitch when I can.
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Offline fredthecat

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Re: What size erlenmeyer flask do you use?
« Reply #16 on: February 27, 2022, 10:29:56 am »
Clean to the eye is not clean to the microscope.
Before disposable syringes, humanity had sterilized by boiling for many years.
We all know the spores argument, which is technically correct, but the possibility that a spore is present and remains viable in a boiled flask is orders of magnitude less than in a sanitized jug.

this is important, because i am planning on using my yeast starters for direct injection into my bloodstream, so they must be medically sterile.

i wish i was just homebrewing 5 gallons of beer that will be gone in a relatively short amount of time, but thats not what people are on this forum for.

narvin

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Re: What size erlenmeyer flask do you use?
« Reply #17 on: February 27, 2022, 04:49:05 pm »
For all practical purposes, a clean flask that  boils water for 15 min is sterilized.

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 The key word is "clean"; if it is perfectly clean, you don't need the boiling.  If it isn't, the boiling won't kill all spores.
Clean to the eye is not clean to the microscope.
 


Exactly.  Boiling is not sterilization.  Spores take time to germinate which is why boiling can render something temporarily sanitary but is not acceptable for storage.

Luckily, sterile is not necessary when dealing with the quantity of a yeast pitch (i.e. not growing from slants).  This is why you can reuse yeast from a previous batch, fermented in a non sterile fermenter, for a long time in the fridge and the limiting factor is yeast health, not contamination.