Sterilize a 5L Flask

Fill it up with water and boil. Very few things can survive that. And the things that can, would likely not have been able to survive the acidity of a lambic.

 

Maybe someone with a electric stove can chime in. I have a gas one, so I’m not sure.
Personally, I wouldn’t. Electric elements have hot spots. I’ve popped a flask before, so I’m extra cautious with them.

I would just put it in a pot with a little water Dutch oven style. Or boil it in your kettle. Or put it in the oven. More that one way to skin that cat!

Fwiw, I make all my yeast starters on the stovetop. Less work and safer that way. I just use a nice low flame.

 

I did a little searching and found mixed views. @jbakajust1 has reported that it works fine for him.

But then, why not boil the starter in a metal pan and then pour it into the flask? (I guess that's what @JohnnyChicago is suggesting.) If you're concerned you could sanitize the flask beforehand, although the boiling wort should kill anything it touches.

 

I mix my water, dme, yeast nutrient, stirbar, and a little fermcap s in the flask, and boil it all together right on the stove with a flap of aluminum foil loosely over the top for 15 minutes. Then put it in the fridge to cool and add the yeast.

 

Boiling the flask in a pot is probably the safest way to go

 

Ah, gotcha. Well, it seems plenty of people use their flasks on glass electric stovetops with no issue, so maybe that will work. You could also boil water in a pot and then pour it into the flask (in a sink or something). The water will retain its heat long enough to kill anything it touches, so if you fill the flask to its brim you should be okay. I would still sanitize it before using, but that would just be to kill anything that had drifted into it in the interim.

Edit: On second thought I would just fill it to the brim with boiling water (letting a little spill over the edges so the brim itself is sterilized), empty it, and cover it with foil. I might wipe the rim with vodka (or rum or whatever) a few seconds before adding the starter wort and yeast. I wouldn't bother sanitizing it if I followed this procedure.

 

I would just do the water and stove top boil. I have a big ass pressure cooker that I use to sterilize and I can't fit the 5L in there. Boil for 25 minutes, let rest with the foil intact until the following morning, then do it again.

 

This seems sensible. A word of warning: do not do this with a teflon pan. When it overheats it will do all kinds of dangerous stuff (release poisonous fumes, smoke, etc.). A stainless pan should be fine, but keep an eye on it because it will get hotter than usual.

 

If you want to avoid heat you can also use vodka.

Swirl the alcohol until it coats all surfaces. Then drain. Then flame the remaining volatile alcohol. A lighter over the top of the flask will burn it off and sterilize the glass.

Cheers.

 

Hmmm, I did not realize the stirbar could be boiled. Been making starters for years and never did that.
BTW, I place flask directly on a flat top electric range. It works, but you need to be careful. Don't increase heat too quickly, and frequently swirl to prevent DME from scorching.

 

Yeah, I believe it’s just a piece of magnetic material coated in Teflon. Lab equipment like stirbars get loads more abuse in a lab than we hit them with.

Interestingly, the one time I broke a flask it was BECAUSE I was swirling...weird.

 

Should be able to put in oven to sterilize, you can google what temp/time. If I had to guess I'd say 300 degrees maybe 15-20 min?

 

More like 350 F for one hour. It is in Palmer’s Book, so check the time and temps.

 

I have boiled water in a glass flask directly on my glass top stove many times without issue. The only time I had a failure.... I spilled a beer on top of the stove.... when the cold beer hit the side of the hot glass, all was lost!

 

You can always rinse with a bleach solution too...this will kill practically any bugs easily. You just need to make sure you rinse the flask REALLY well so there's no residual chlorines left to cause off flavors in your final beer.