Boiling starters in a flask

I began making starters a while ago and recently got a flask. I like boiling the starter in the flask, but have a hell of a time dealing with foam from the boiling wort, which wants to shoot out all over the stove. Any suggestions on how to deal with that?

Used a flask for the first time last week.  Was really tentative about cracking the glass on the stove.  So I kept the heat at “medium”.  Did not see much foaming but did lower the heat once I saw a decent boil.

Sure was nice to use the flask!  Now what to do with the half gallon glass jug i was using…

Back when I used to make starters that way (use canned wort now), I too was never comfortable with boiling in the flask.  I chose to eliminate the boilover issue by boiling in a regular pan.  This also speeds up the chilling process in that I could ice-water bath chill in the pan before pouring into the flask.  Great way to kill a flask is to take it off the burner where it was boiling and plunk it in an ice-water bath the chill.

A lab flask shouldn’t be much worry on the stove - this is what they are made for. Hot stove to ice water might be a little too much for it though.

There’s a product called Ferm-Cap that comes in little 1 oz. dropper bottles. One drop in a 2L flask has kept my starters of that size from foaming out/boiling over.  Works well for preventing wort boil overs as well. Some folks have concerns about using it as it is silicone based. I’ve decided to only use it only as needed which for me ends up being only occasionally in starters boiled in the flask.  If I boil in a pot and monitor closely there’s no need.

Boiling to ice water is of more concern for me too as it would be a real bummer to break a flask and lose a starter.  I like to more gradually reduce the glass temperature by holding the flask with a oven mit and running it under hot tap water and gradually reducing the temperature of the flowing water until it’s cold. Then I place the flask in a large bowl fill it with cold water. Finally displace the water in the bowl gradually with ice cubes until it’s mostly ice. Has worked well for me with no crackage.

I use this in my starters and in my boil kettle.  One or two drops is all you need.

Tried boiling in a flask a couple and for me it was more hassle than it was worth.  I now boil and cool in a pot, then xfer to a gal. glass jug.  No boilovers, no worry about breaking the flask, and the jug is twice the size of the flask.

I use this stuff too and it works great.  And it doesn’t have any affect on you, as my picture here indicates:

toxicavenger7.jpg

;D

I boil in the flask, use fermcap, and move the flask from the stove directly to a sink full of cool tap water.  Never had any problems with it but maybe I’ve just been lucky.  I guess that could be one of those things that works just fine until it doesn’t.

I like making them in the flask because it’s quick and easy and the starter vessel is automatically sanitized.  No need to mess around with a pot and a flask and a funnel etc.

I like boiling in a flask because it helps me achieve my definition of awesome.

Another vote for fermcap. One or two drops and you’ll have no boilover issues.

I used to boil in a flask on a glass-top stove, but that ended when I had a minor boilover and that resulted in a cracked and destroyed 4L flask.  Definitely not worth it.  I now boil in a pyrex measuring cup in a microwave oven and then transfer the cooled starter wort into the flask.  Much safer, and the potential and severity of boil overs is reduced.

I boil on the stove in a 4l flask with some fermcap, then put it on the stirplate to let it cool overnight, then add the yeast.  No boil overs or other problems.

I boil in a flask on the stove with fermcap then chill and move to a stirplate. Boilovers are far and few between. I have found this method to be very practical.

most of the time I boil my starters in a sealed pint or quart jar with a two piece lid under 15 psi.

I have boiled in a flask with no problems. I can see the benefit of a more or less sterile environment for your starter, at least until you remove the foil. but flasks are expensive and I am cheap and one gallon jugs are also cheap thus…

I boil in a small saucepan and chill it quickly with an ice bath before transferring. Never had a boilover, no need for Fermcap, etc.

To avoid the boil over, simply move the flask to the side such that only 1/4 to 1/3 of the flask is receiving heat from the burner.  Then, turn the heat down.  This will allow you to create a low, rolling boil in the flask like you do in your brew kettle.  Just monitor the heat so that you maintain only enough heat to keep it rolling  Any more is unnecessary and will cause a boil over.

One thing to be cautious of is making a starter with pilsner malt that you intend to pitch whole.  The flask, by its shape, is designed to minimize vapor loss.  The vapors collect on the side of the glass and slide back down into the base liquid.  Thus, you do not boil off any DMS from pilsner malts or extra light DME.  If after you make your starter you are going to chill and decant the liquid, then no big deal.  If I need to boil down my wort or am worried about boiling off flavors compounds out, then I will boil in a pot first, then transfer to the flask.  Then I will boil in the glass for 5 minutes just to make sure everything is sanitized.

Lab grade glassware will handle any stove and can be immediately dunked into ice baths.  The only concern is the depth of the ice bath.  Make sure it is not much deeper than the liquid inside the flask.  If you have 1-2" of wort in your flask and you dunk the flask in 6-8" of ice, then you do risk cracking the upper part of the flask that is not also in contact with liquid inside.

The problem I had with simply reducing heat is that I have a ceramic cooktop stove and the elements cycle on/off at low settings. Even at vary low settings the flask would boil over when the element cycled on.

But I did get some Fermcap S last weekend and my starter last night boiled hard without foaming all over the place. Praise Jebus.

They are designed to go from boiling to an ice bath.  I do starters when I go home for lunch, my wife hates the smell of boiling wort so I make them while she’s at work.  I take them off the stove and put them directly into an ice bath so I can pitch the yeast before I go back to work.  I’ve been making starters this way for 10 years.
The trick is to use medium heat just until you see bubbles coming off the bottom, and then slow the heat down very low so the wort simmers for 15-20 minutes.