Sterilizing larger Erlenmeyers?

[user 246304]

OK, this is as dumb as it gets.

I pressure cook wort in mason jars at 15 psi, etc.

In wanting to check out the properties of a Brewlab yeast, at the suggestion of another member, I want to do a simple stirplate propagation. My first time through I ended up with massive phenols and I think it was probably my poor technique, not the slants I'm using. So I want to do it again.

I have an assortment of glass, with erlenmeyers 50, 250, 1L, 3L, 5L.

So I poured wort into both the 250 and 1L flasks, and along with other stuff went to pressure cook everything. I have a dozen or so sterile 10ml test tube fills.

The 1L didn't fit.

I used to have a massive pressure cooker, and this one, though large, is, er, um...smaller. I never thought to check what flasks can fit in there. Dumb, embarrassing to admit.

How do you guys sterilize your larger flasks (all the way to 5L), presuming sterile wort as I have, in mason jars?

I'm also loathe to direct boil the flasks on the stove because although they're all borosilicate, I'm not sure of the mix of "student" v. "lab grade."

 

[LLBeanJ]

I don't sterilize my flasks. I sanitize the flask with Starsan, dump my pressure-canned wort into the flask, and add my yeast. Been doing it this way for 6 years.

 

[Braufessor]

Yeah - I suppose you could submerge the entire thing in boiling water. Maybe putting it in an oven at a relatively low temp..... Or, if you had access to a commercial/lab with an autoclave.... But, I have never worried about sterilizing a flask. I alternate Iodophor and Star San in order to sanitize.

 

[user 246304]

I don't sterilize my flasks. I sanitize the flask with Starsan, dump my pressure-canned wort into the flask, and add my yeast. Been doing it this way for 6 years.

I'm comfortable with sanitization at later stages, but try to sterilize as long as possible. I'm probably just being anal.

Edit: Brau, crossed in the mail. Damn my memory. It's true I had an awesome, huge pressure cooker the last time I was brewing, but now I'm almost certain even that one could only handle flasks below 1L, so I had to have sanitized only. I've never used the dry heat method.

 

[GoeHaarden]

Foil the top and bake them at 200F for an hour or so should do the trick. I've done that for my pyrex erlenmeyers without any issues...

 

[RM-MN]

Foil the top and bake them at 200F for an hour or so should do the trick. I've done that for my pyrex erlenmeyers without any issues...

Exactly what I would do but raise the temperature. He/she asked for sterilizing the flasks and botulin spores can survive boiling temps. At 200, everything but the botulin spores die and that covers pasteurization. At 250 even the botulin spores die. That makes them sterile.

 

[GoeHaarden]

Exactly what I would do but raise the temperature. He/she asked for sterilizing the flasks and botulin spores can survive boiling temps. At 200, everything but the botulin spores die and that covers pasteurization. At 250 even the botulin spores die. That makes them sterile.

Good point. Honestly, you could probably even go hotter if you wanted. I mean we bake food in pyrex dishes at 350F and up.

 

[Renegade Brewer]

We use a 5000ml flask and boil my starter wort directly in the flask. We put a piece of tin foil on top and let the steam roll up through the foil. 10 minutes boiling in the flask, cool to 65, then spray the outside of my yeast container with star San and pitch the yeast. On the stir plate it goes for 48 hours.

The flasks are designed to withstand boiling, so that’s a great way to sanitize them

 

[mongoose33]

Couldn't you just boil some water in one of those flasks for 15 minutes or so? I have both a 2-L and a 5-L flask, and if I wanted to sterilize it, I'd just boil some water in it, maybe 3 liters-worth.

 

[day_trippr]

Baking at 250°F seems optimal in lieu of a suitable PC or autoclave, it's essentially the same temp you're going for with a PC.
Should be no risk to the e-flask, even student grade

fwiw, I don't do any of that, relying on Star San, but then again I'm not storing raw wort...

Cheers!

 

[yourlastchance89]

Boiling in the flask won't sterilize, but it should kill 99% of what we deal with as homebrewers. Contracting a pathogen that is able to withstand boiling temps and the duration taken to cool to room temp is negligible

 

[beermanpete]

To sterilize in dry heat you need to heat to 350°F. I have done that with beer bottles without issue so the borosilicate will surely be ok.

 

[mongoose33]

Boiling in the flask won't sterilize, but it should kill 99% of what we deal with as homebrewers. Contracting a pathogen that is able to withstand boiling temps and the duration taken to cool to room temp is negligible

Help me out here. Maybe I'll be learning something new.

What won't boiling the flask sterilize? It is a given that boiling wort kills any ne-er-do-wells that might creep in on the cold side. What would boiling an Ehrlenmeyer flask not do that boiling the wort does?

I know people are sometimes concerned about botulinum spores, but they're anaerobic, closed system organisms. Never, ever, have I read about anyone having beer that has botulinum toxin in it.

 

[Braufessor]

Help me out here. Maybe I'll be learning something new.

What won't boiling the flask sterilize? It is a given that boiling wort kills any ne-er-do-wells that might creep in on the cold side. What would boiling an Ehrlenmeyer flask not do that boiling the wort does?

I know people are sometimes concerned about botulinum spores, but they're anaerobic, closed system organisms. Never, ever, have I read about anyone having beer that has botulinum toxin in it.

I think he is just trying to eliminate any potential microbes that could be on the flask itself. He is propagating yeast up from slants...... so, in dealing with small amounts of yeast and multiple transfers to increasingly bigger starters, you end up opening up opportunity for something else to get a "foot hold". Normally, when you are dumping a ton of yeast into a beer and dropping pH, increasing alcohol..... that becomes less of an issue. However, sounds like he is trying to grow up a small amount of yeast into a pure culture.

 

[mongoose33]

I think he is just trying to eliminate any potential microbes that could be on the flask itself. He is propagating yeast up from slants...... so, in dealing with small amounts of yeast and multiple transfers to increasingly bigger starters, you end up opening up opportunity for something else to get a "foot hold". Normally, when you are dumping a ton of yeast into a beer and dropping pH, increasing alcohol..... that becomes less of an issue. However, sounds like he is trying to grow up a small amount of yeast into a pure culture.

I get this. The question I have is why boiling won't work, when it clearly works when we're brewing.

I know a little bit about this, but sometimes a little is not enough. But here goes: People are concerned about botulinum spores becoming botulinum bacteria, which produce neurotoxins. Boiling the toxins for 10 minutes will render them inert. The spores are anaerobic, meaning they only grow in an atmosphere devoid of oxygen. This is why you have to pressure-can foods that are not highly acidic, to get the temperature to the 240-degree range where the spores are killed.

Based on what I've read, those spores are not dangerous by themselves. Further, according to this from the USDA, "C. botulinum cannot grow below a pH of 4.6". Finished beer is lower than that, which is presumably why we aren't dying of botulinum toxin when we drink beer.

So. If it's spores with which we are concerned, they aren't going to "hatch" under a normal yeast-starter regime. It's not anaerobic. So I'm back to why it's necessary to sterilize further than what boiling will accomplish.

Maybe there's something here I don't know. Wouldn't be the first time. Maybe there's some other microbiological nasty with which we need to concern ourselves. The purpose of my noting all this is that it's how I understand it--but maybe that's wrong, and if so, I'll be happy to learn something more.

 

[Braufessor]

I get this. The question I have is why boiling won't work, when it clearly works when we're brewing.

I know a little bit about this, but sometimes a little is not enough. But here goes: People are concerned about botulinum spores becoming botulinum bacteria, which produce neurotoxins. Boiling the toxins for 10 minutes will render them inert. The spores are anaerobic, meaning they only grow in an atmosphere devoid of oxygen. This is why you have to pressure-can foods that are not highly acidic, to get the temperature to the 240-degree range where the spores are killed.

Based on what I've read, those spores are not dangerous by themselves. Further, according to this from the USDA, "C. botulinum cannot grow below a pH of 4.6". Finished beer is lower than that, which is presumably why we aren't dying of botulinum toxin when we drink beer.

So. If it's spores with which we are concerned, they aren't going to "hatch" under a normal yeast-starter regime. It's not anaerobic. So I'm back to why it's necessary to sterilize further than what boiling will accomplish.

Maybe there's something here I don't know. Wouldn't be the first time. Maybe there's some other microbiological nasty with which we need to concern ourselves. The purpose of my noting all this is that it's how I understand it--but maybe that's wrong, and if so, I'll be happy to learn something more.

I guess I am not really talking about botulinum in particular..... I am just talking about microbes in general.

When you say "it works" when brewing....... well, it doesn't. Every batch of beer we make has "contaminating" microbes in it. It is just that we are introducing an overwhelming amount of yeast, so the undesirable microbes never occupy a large enough foothold for the most part to matter - but they are there. And, from generation to generation they increase. If you are starting with a small amount of yeast, any undesirable microbes then represent a much higher percentage in your wort by definition......I think the opportunity is just greater to accelerate their foothold.

Personally, boiling, sanitizing, etc. would be good enough for me. But, if I was going to argue for sterilizing...... that would be my rationale.

 

[RM-MN]

It appears that there is a problem differentiating between pasteurization and sterilization. Pasteurization takes care of nearly all the microbes we as brewers are concerned with but there is that dang botulin spore that can survive the boiling so in some cases we really do need to be concerned with making something sterile. Canning wort is one of those and propagating yeast is probably another. We don't worry about most of the microbes in our fermenting beer. It's there but because of the competition of the yeast (big numbers of yeast, small numbers of microbes) and the acidic beer plus the CO2 that is produced plus the anitseptic properties of hops the microbes don't have a chance to grow. Wort is not acidic enough and doing a hot water bath cannot kill the botulin spores which can then propagate in the wort and since botulism can kill you, we really try to get you to be aware and do pressure canning to keep you alive.

 

[user 246304]

Thank you everybody, lots to consider. Just to clarify, brauprofessor probably said it best as to my concerns. I pressure can my wort at 15psi pure steam, so am not concerned about toxic spores entering into the propagation stream. It's concern about typical spoilage species having a leg up on my yeast culture during the earliest stages. I'm dragging from a slant into 10 ml sterilized wort and tube, from there, to 100 - all good, as my 250 ml flask isn't an issue and the wort is simply re-"autoclaved" from the mason jars. These all get darker, but that's the only issue.

So, I was trying to find a way to keep an aseptic or sterile atmosphere up to the point the yeast have the ability, or at least have a good chance, of outcompeting spoilers, just as we do when we pitch yeast into cooled wort. Say, up to a 2000 ml step: 10-100-500-2000, with the 500 going into a 1L flask (won't fit), the 2000 going into the 3000 ml flask (definitely won't fit!). Like trippr and others, I thought to sanitize but I'd be more comfortable to sterilize.

I think the best I can probably do (not wanting to direct-fire the glass, rationally or not), is dry-heat according to accepted protocols; liquid transfer as with any other liquid media (2 test tubes or slant(s) - flame, alcohol, etc.).

 

[yourlastchance89]

I get this. The question I have is why boiling won't work, when it clearly works when we're brewing.

I know a little bit about this, but sometimes a little is not enough. But here goes: People are concerned about botulinum spores becoming botulinum bacteria, which produce neurotoxins. Boiling the toxins for 10 minutes will render them inert. The spores are anaerobic, meaning they only grow in an atmosphere devoid of oxygen. This is why you have to pressure-can foods that are not highly acidic, to get the temperature to the 240-degree range where the spores are killed.

Based on what I've read, those spores are not dangerous by themselves. Further, according to this from the USDA, "C. botulinum cannot grow below a pH of 4.6". Finished beer is lower than that, which is presumably why we aren't dying of botulinum toxin when we drink beer.

So. If it's spores with which we are concerned, they aren't going to "hatch" under a normal yeast-starter regime. It's not anaerobic. So I'm back to why it's necessary to sterilize further than what boiling will accomplish.

Maybe there's something here I don't know. Wouldn't be the first time. Maybe there's some other microbiological nasty with which we need to concern ourselves. The purpose of my noting all this is that it's how I understand it--but maybe that's wrong, and if so, I'll be happy to learn something more.

He specifically used the term sterilize in his original post. To sterilize is to eliminate all microorganisms, which boiling is incapable of doing, more specifically with endospore bacteria when it comes to brewing, and wort doesn’t sit at a 4.6 pH. Utilizing a pressure cooker, baking at 350 degrees Fahrenheit for 2 hours, or if you have the patience for it Tyndallization. Boiling works for most of what we would deal with for home brewing, but when it comes to propagating slants or plates one would want to utilize sterilizing techniques to ensure colonies that are as pure as possible.

 

[user 246304]

Everybody wanted to thank you. Just read a post (and lost it) by Kai, talking of sterilization for the first two steps then sanitizing, and that seems reasonable to me, as it is with most if not all of you. And it is what it is - I don't recall how large my original PC was, and don't recall therefore how large of flasks I could fit in there but it doesn't matter, really - at some point, we move from aseptic technique to potentially risking nasties. It my setup it will generally be after 100 ml going to 500 ml in a 1L flask that I'll simply StarSan the flask, flame the lips of both, and go from there.

Very much appreciate your help, everyone.

 

[Northern_Brewer]

I think a lot depends on where you're coming from - brewers tend to be a bit less paranoid about these things, whereas those with microbiological experience are constantly amazed that beer ever manages to get made.... Coming from a micro background where it was normal to have a medical-grade autoclave running at least once a day (plus another run for waste), I tend to the paranoid side so I like to feel that everything up to 500ml at least has been autoclaved "in situ", in part because I'm missing things like laminar flow cabinets that were the norm in my previous life. And unlike many brewers, I'm doing the full yeast ranching thing so am working down to the single-colony level.

So at the moment I have a "normal" domestic pressure cooker, but it's a bit knackered and I've been looking to replace it. It's big enough for a 1l Schott bottle but Ehrlenmeyers are a bit of a squeeze. I think this new wave of electric pressure-cookers (Instant Pot was the original but there's now lots of cut-price clones) would be ideal for home autoclave purposes (having timer control is great for people as easily distracted as me <g>) as they're barely more expensive than a similar-sized stove-top pressure cooker. But since Instant Pot is fairly low and wide, that's the shape they tend to follow so even 6 litre ones are nowhere near tall enough for my 1l bottle. Has anyone seen any of those things that will accommodate a 1l bottle? If I could buy one at a sensible price then that would do me. At the moment it's looking like I'll buy one of the smaller automated electric ones for day-to-day autoclaving of Petri dishes, Eppendorfs, McCartneys etc and make do with my current stove-top one for bottles, with a view to buying a bigger stove-top one when this one finally dies completely. Commercial stove-top pressure cookers are relatively reasonable by homebrew kit standards - you can get a 20-25 litre pot for about the same as a Fermentasaurus.

So - anyone seen a "tall" electric pressure cooker?

 

[MaxStout]

So - anyone seen a "tall" electric pressure cooker?

Interesting...out of curiosity I did a quick search on Amazon for "electric pressure cooker" and saw dozens of entries, all of which look rather squat. I then did a search for autoclaves on Amazon, and found this, though the reviews are not flattering. Maybe there is something akin to that somewhere near you, but of better quality.

If I could get a good deal on a small autoclave on Ebay or Craigslist, I'd probably do it. Just for all the little things I'd like to sterilize. And I like gadgets.

 

[Northern_Brewer]

Interesting...out of curiosity I did a quick search on Amazon for "electric pressure cooker" and saw dozens of entries, all of which look rather squat. I then did a search for autoclaves on Amazon, and found this

Yep, we had one of those or similar in one lab as our "little" autoclave for those "I've missed the main autoclave run but I really need to get these plates poured and streaked TONIGHT!!!!!" moments. It may have been a different brand, but worked fine. The only trouble is that like stovetop ones it needs you to keep an eye on it to see when it starts boiling, and to remember to put a timer on it to switch it off after 20 minutes. Which requires you to pay attention unless you rigged up an Arduino or something to monitor temperatures and switch it off. On the bright side, they do tend to cope better than domestic pressure cookers with boiling dry and exploding bottles!

But if you put the word "autoclave" on something that doubles the price, and the word "medical" will triple the price. So that's why I was looking at stuff that's aimed at kitchens - these Instant Pot clones are so nearly ideal, if only there was one that could take a Schott bottle.