Beaker vs Erlenmeyer Flask for a starter

If you use a stir plate to make a yeast starter, I always see talk of using an
Erlenmeyer Flask. I have one myself. (Borosilicate 2 liter - has a small bubble in one part)


The problem with the Erlenmeyer Flask is its rather large (I have a 2 liter flask).
A beaker is smaller since its more compact. A beaker would sit well on a stir plate. And it take sup less space in the refrigerator when cold crashing the starter after its done (so it can be decanted)

What advantage does a Borosilicate Erlenmeyer Flask over a Borosilicate Beaker?



Since flasks are known to break, I boil the starter wort and transfer it to the flask (there is a 20 second risk of infection), inoculate the wort, and set it on the stir plate for a couple of days, then place it in the fridge to cold crash it. I decant off most of the spent wort (beer), and dump it into the fermenting bucket.


If I want to boil the starter in the Borosilicate, would it help prolong its life, (and prevent a mess) if I placed it in a small pot with water and boiled the wort (inside the flask) while the flask is sitting in the pot, absorbing the heat from the water as opposed to the direct flame?

Is this an adequate heat shield, or can anyone suggest something better?

Borosilicate is pretty tough stuff when it comes to heat. Yes, if yoy heat it till it glows and then pour water in you will break it but in the course of normal use (fill and put on a hot plate or over a burner) you will not. You are much more likely to break it by dropping it.

The main advantage the flask has over the beaker (and there is an intermediate container called a 'fleaker') is the narrow neck and mouth which is easy to seal with foil, a cotton ball or an airlock thus reducing the chances of contamination during cooling of the wort and fermentation of a starter. The main disadvantage is the narrowing top increases the chances of boil over.

If I want to boil the starter in the Borosilicate, would it help prolong its life, (and prevent a mess) if I placed it in a small pot with water and boiled the wort (inside the flask) while the flask is sitting in the pot, absorbing the heat from the water as opposed to the direct flame?

Click to expand...

that is essentially whats called a double boiler, and yes you can do that. as long as you are careful, though, theres not much harm in boiling directly in the flask over a flame. whichever you prefer is fine.

What size starters are you thinking about? I regret buying the 2L flask because a stirred 1 gallon jug works great for 1L-3L starters.

I've decanted by pouring, but like using a short piece of 1/4" polyethylene tubing from Home Depot ($2 for 25') to gently siphon into the sink after at least a day of chilling the starter in the fridge. You can get down to wort levels that are barely enough to get the yeast out.

>.What size starters are you thinking about? I regret buying the 2L flask because a stirred 1 gallon jug works great for 1L-3L starters.

I have a 2L flask. For really big starters I can always step them up. Make a 2L starter, cool it for a couple of days, decant off 85% of the liquid and make a new 2L starter.

Decanting seems to pour off 80%+ of the liquid, while retaining the yeast mass at the bottom (after a couple of days in the fridge)

2L starters in a 2L flask is getting close to a boil-over/krausen disaster. I've found bigger containers that you don't boil in are cheap and avoid accidents, personal preference.

It may be better to double your starter volume when stepping-up. Your 2L + 2L stirred starter should make about 600 billion yeast cells. A 1L + 3L stirred starter would make the same with an innoculation rate < 100 million cells/mL and more growth in the second step.

I rarely use my 2L flask these days and use my 5L flask regularly. Then again I'm often brewing 7-10g batches.

Williams Brewing also sells a 3L flask. Great for people who do 5-6G batches and find that the 2L is too small and 5L is overkill.