Pressure cooker or Instapot?

[redrocker652002]

OK, so I have been reading the stuff about freezing a yeast bank and I am really interested in this. My wife has an Instapot, which she thinks won't work. I am just curious if it will? When putting the solution of water and glycerine in the pressure cooker, are you just doing that to sterilize, or are you actually canning it? I am guessing just sterilizing and I am guessing the instapot would work ok. But I defer to the experts.

 

[NSMikeD]

Instapot is a pressure cooker. What do you mean by "just canning it? I am not an expert, but I do know from other activities that the pressure cooker is sterilizing. Pressure cookers can get the water up to 250° (Boyle's Law) , whereas boiling water is approximately 212° depending on where you live. While boiling water does a good job at sterilizing, certain wild yeast strains can survive that temperature.

I have a Nuvo Duet, basically an Instapot with a second lid that serves as an air fryer, and it is most certainly a pressure cooker in every sense of the way when set up to pressure cook.

Now having been married 20 years and divorced for another 10, I would consider she doesn't want you using her Instapot for your hobby experiments and has nothing to do with the logic that an Instapot is a pressure cooker. You can get your own brand new basic pressure cooker for like $30 and keep peace in the family.

 

[wootz001]

I recently went down this rabbit hole. There are a lot of variables specific to your needs and location (altitude, specifically). Strongly recommend checking out USDA Complete Guide to Home Canning for the basics: https://nchfp.uga.edu/publications/usda/GUIDE01_HomeCan_rev0715.pdf

I ended up getting a standard pressure canner, a Presto 23 quart. My thoughts were that it having a gauge I can verify the pressure is built up, and controlling the heat manually on the stovetop I can start a timer to ensure it processes for the right amount of time.

 

[pvpeacock]

I started freezing yeast earlier this year. I may be wrong, but I do not think that putting the water and glycerin in a pressure cooker is meant to sterilize the solution. My impression is that doing so is necessary to mix/combine the water and the glycerin which otherwise remain separate.

Having a pressure cooker is also handy for making starter wort for yeast starters. This definitely requires a pressure cooker to sterilize/can the wort for long term storage. See https://brulosophy.com/2023/05/25/the-brulosophy-show-canning-wort-for-yeast-starters/

 

[redrocker652002]

Instapot is a pressure cooker. What do you mean by "just canning it? I am not an expert, but I do know from other activities that the pressure cooker is sterilizing. Pressure cookers can get the water up to 250° (Boyle's Law) , whereas boiling water is approximately 212° depending on where you live. While boiling water does a good job at sterilizing, certain wild yeast strains can survive that temperature.

I have a Nuvo Duet, basically an Instapot with a second lid that serves as an air fryer, and it is most certainly a pressure cooker in every sense of the way when set up to pressure cook.

Now having been married 20 years and divorced for another 10, I would consider she doesn't want you using her Instapot for your hobby experiments and has nothing to do with the logic that an Instapot is a pressure cooker. You can get your own brand new basic pressure cooker for like $30 and keep peace in the family.

Thank you for the response. I will ask more questions. She has supported my hobby to a point where she gets into more than I do sometimes. So, I don't think that is the issue at all It might be me not understanding the differences or her not understanding what I am looking to do. Either way, thanks for the input, I will keep trying LOL

 

[whoaru99]

Can you point me to where the question about pressure cooking/sterilizing the solution comes from? I'd like to see it in it's native context.

 

[pvpeacock]

I don't recall if either explain why you need a pressure cooker, but here are the two sources I used to start freezing yeast.

https://brulosophy.com/2023/10/12/the-brulosophy-show-how-to-freeze-yeast-and-keep-it-for-years/
https://homebrewacademy.com/frozen-yeast-bank/

 

[Gadjobrinus]

An Instapot will not reach 15 psi, so it won't reach 250F, and it won't sterilize spores. For that typically you will need a stovetop pressure cooker, like the Presto, Mirro or All-American. I'm in the hunt myself, as I regretfully sold my 21.5 qt All-American when I sold all my brewing gear several years back.

 

[whoaru99]

FWIW, we have Instant Pot Max. Says 15psi on the Max setting in the user manual for that one.

 

[Agent]

For small containers of aqueous product, 10psi/240F is also adequate for sterilization.

 

[NSMikeD]

This gets interesting. According to a Michigan State article I just read, a pressure cooker is not a pressure canner. A pressure canner is larger (not an issue for yeast) and, more importantly, can create 15psi for sterilization, which includes a gauge to provide certainty. According to the article, pressure cookers typically only go to 12 psi and do not include a gauge to confirm the internal psi.

Furthermore, according to Instapot, they claim: "In pressure cooker mode, the Instant Pot operating range (when set on high pressure) is 10.2~11.6 psi, which corresponds to a steam temperature of 240F to 244F. The safety release set point is 15.2 psi or 250."

More on this, sterilization is a function of time and temperature. There are times when an item cannot withstand 250° and so there is low temp sterilization which basically extends the time to hours and even cycling over days.


Much of the canning 250° threshold is to be sure you are quickly killing botulism spores.


Reading a few more articles on freezing yeast banks, the consensus is that an instapot will do the job for the homebrewer. You are not selling guaranteed pure yeast banks, and you are not preserving food. The temp and pressure of the instapot or home pressure cooker is more than likely sufficient to provide high quality frozen yeast.

Even in the best sanitary homebrewing conditions and Felix Unger-like attention to germ combat, your beer will be exposed to wild yeast, but at levels that the pitched yeast, will just overtake them to a negligible level.

This brings us back to the most important homebrewing axiom:

relax,
don't worry,
have a homebrew, and
use the Instapot.

 

[NSMikeD]

I recently went down this rabbit hole. There are a lot of variables specific to your needs and location (altitude, specifically). Strongly recommend checking out USDA Complete Guide to Home Canning for the basics: https://nchfp.uga.edu/publications/usda/GUIDE01_HomeCan_rev0715.pdf

I ended up getting a standard pressure canner, a Presto 23 quart. My thoughts were that it having a gauge I can verify the pressure is built up, and controlling the heat manually on the stovetop I can start a timer to ensure it processes for the right amount of time.

^^^^. This


So we see that sterilization for low-acid foods occurs between 240° - 250° (keep in mind that time is also a factor)


while wort is a low acid environment, which would only require boiling temp to sterilize, glycerol is a weak base, thus the need for a higher temp to sterilize - in case you were wondering why boiling wort is deemed to be sanitized but the glycerin solution needs 250°.

 

[whoaru99]

Furthermore, according to Instapot, they claim: "In pressure cooker mode, the Instant Pot operating range (when set on high pressure) is 10.2~11.6 psi, which corresponds to a steam temperature of 240F to 244F. The safety release set point is 15.2 psi or 250."

I have a real, honest to goodness large pressure canner so I don't have a really big dog in the fight.

But, I also have an Instant Pot, and some do have 15psi capability.

 

[Gadjobrinus]

while wort is a low acid environment, which would only require boiling temp to sterilize

Did you mean to say, low acid, requiring the elevated temp to sterilize?

 

[Gadjobrinus]

I have a real, honest to goodness large pressure canner so I don't have a really big dog in the fight.

But, I also have an Instant Pot, and some do have 15psi capability.

View attachment 842382

Good for you and that's great to know. I'd only read they can get to the 12 or so mentioned above. I've got an 8 quart stovetop that works well, for what it is, but I can't get much in there but culture tubes, etc. Pretty dumb move to sell of the 21.5 All-American. I see alot of Instapots on Nextdoor and CL, but looking for the behemoth tank now. I'm amazed they've gone up as high as they have.

 

[NSMikeD]

Did you mean to say, low acid, requiring the elevated temp to sterilize?

the opposite. low acid food require lower temp (180° - 212°) for sterilzation. The acid is helps prevent spores, yeast etc for doing their thing. Wort pH is in the 5s, so we let the boiling sterilize it before pitching yeast.

 

[whoaru99]

Mine isn't as fancy as the thumb screw lid style like All American, but it's an OK Presto 23qt model.

 

[NSMikeD]

Good for you and that's great to know. I'd only read they can get to the 12 or so mentioned above. I've got an 8 quart stovetop that works well, for what it is, but I can't get much in there but culture tubes, etc. Pretty dumb move to sell of the 21.5 All-American. I see alot of Instapots on Nextdoor and CL, but looking for the behemoth tank now. I'm amazed they've gone up as high as they have.

Could max psi and operational psi be different? For example, while Instapots says they cook at 240° at 12 psi, they also rate the release valve to be about 15 max psi. I bet it's an average range thing and that they get up to 15psi during a pressure cook, just that the heating element cycles off before it turns back on to continue the cook.

 

[Gadjobrinus]

the opposite. low acid food require lower temp (180° - 212°) for sterilzation. The acid is helps prevent spores, yeast etc for doing their thing. Wort pH is in the 5s, so we let the boiling sterilize it before pitching yeast.

That's not correct Mike. Low acid foods require the higher temperature for safety. It's why meats, for instance, need the 250 but tomato sauce doesn't. Here, for instance:

Food acidity and processing methods​

Whether food should be processed in a pressure canner or boiling-water canner to control botulinum bacteria depends on the acidity of the food. Acidity may be natural, as in most fruits, or added, as in pickled food. Low-acid canned foods are not acidic enough to prevent the growth of these bacteria. Acid foods contain enough acid to block their growth, or destroy them more rapidly when heated. The term "pH" is a measure of acidity; the lower its value, the more acid the food. The acidity level in foods can be increased by adding lemon juice, citric acid, or vinegar.

Low-acid foods have pH values higher than 4.6. They include red meats, seafood, poultry, milk, and all fresh vegetables except for most tomatoes. Most mixtures of low-acid and acid foods also have pH values above 4.6 unless their recipes include enough lemon juice, citric acid, or vinegar to make them acid foods. Acid foods have a pH of 4.6 or lower. They include fruits, pickles, sauerkraut, jams, jellies, marmalades, and fruit butters.

Although tomatoes usually are considered an acid food, some are now known to have pH values slightly above 4.6. Figs also have pH values slightly above 4.6. Therefore, if they are to be canned as acid foods, these products must be acidified to a pH of 4.6 or lower with lemon juice or citric acid. Properly acidified tomatoes and figs are acid foods and can be safely processed in a boiling-water canner.

Botulinum spores are very hard to destroy at boiling-water temperatures; the higher the canner temperature, the more easily they are destroyed. Therefore, all low-acid foods should be sterilized at temperatures of 240° to 250°F, attainable with pressure canners operated at 10 to 15 PSIG. PSIG means pounds per square inch of pressure as measured by gauge. The more familiar "PSI" designation is used hereafter in this publication (the Complete Guide to Home Canning). At temperatures of 240° to 250°F, the time needed to destroy bacteria in low-acid canned food ranges from 20 to 100 minutes.

The exact time depends on the kind of food being canned, the way it is packed into jars, and the size of jars. The time needed to safely process low-acid foods in a boiling-water canner ranges from 7 to 11 hours; the time needed to process acid foods in boiling water varies from 5 to 85 minutes.

 

[NSMikeD]

That's not correct Mike. Low acid foods require the higher temperature for safety. It's why meats, for instance, need the 250 but tomato sauce doesn't. Here, for instance:

thanks. The diagram in the linked USDA was misleading. Visually it appeared that is way saying water boiling point was for low acid food, but a second look at the wording it was actually making the opposite point. Which is confusing since acid, be it star san or any other acid based contact sanitizer, is preferred over bleach in the food industry

anyway. I appreciate the correction.

 

[Gadjobrinus]

thanks. The diagram in the linked USDA was misleading. Visually it appeared that is way saying water boiling point was for low acid food, but a second look at the wording it was actually making the opposite point. Which is confusing since acid, be it star san or any other acid based contact sanitizer, is preferred over bleach in the food industry

anyway. I appreciate the correction.

You bet.

 

[NSMikeD]

You bet.

ahh. it's the presence of air that makes acid based sanitizers acceptable in food service. Botullism spores need less than 2% oxygen to thrive. since we aren't concerned about food poisoning with freezing yeast but rather keeping wild yeast from developing, the canning sterilizing standards come into dicussion.


Great thread; I enjoy learning new things that I can use to bore someone at a party.

 

[redrocker652002]

So after it is all said and done, will my wife's instapot do the job? Like I said, I am not in the position right now to do this, but it would certainly settle an argument as she says emphatically that it won't. I would love to say, but yes it will. LOL.

 

[Gadjobrinus]

ahh. it's the presence of air that makes acid based sanitizers acceptable in food service. Botullism spores need less than 2% oxygen to thrive. since we aren't concerned about food poisoning with freezing yeast but rather keeping wild yeast from developing, the canning sterilizing standards come into dicussion.


Great thread; I enjoy learning new things that I can use to bore someone at a party.

Yep, right - anaerobic botulism is the concern. Not an issue when air is involved.

 

[NSMikeD]

So after it is all said and done, will my wife's instapot do the job? Like I said, I am not in the position right now to do this, but it would certainly settle an argument as she says emphatically that it won't. I would love to say, but yes it will. LOL.

yes.

Not as effective as a canning pot but for a home brewer, it would sufficiently kill enough wild yeast spores that you would never notice in the unlikely event any survived. Just cook for 30 minutes instead of 10 to feel better about 240° @ 12 psi

be careful, you are both right

if you were a commercial outfit and needed to guarantee the purity of a large stain, then no. But of course, you wouldn't have considered an instapot in the first place.


If you were canning food where botulism in an aerobic room temperature environment was a concern, I'd opt for the safety of a canning pot with a gauge.

So be prepared to concede the later two points. But, IMO, you are right about freezing yeast for home brewing.

 

[pvpeacock]

Again, I don't think the cryo-preservative needs to be sterilized because it is just water and glycerin. There is no yeast or wort or beer in it when it is heated. The yeast is not added until after the cryo-preservative has been made and the two are mixed on a test tube for freezing.

 

[mac_1103]

So after it is all said and done, will my wife's instapot do the job?

As already mentioned, it depends. If it's one of the high end ones that can get up to 15 PSI, then definitely yes. If it can only do 12 PSI, then it's still probably fine if you just increase the time a little.

I don't think the cryo-preservative needs to be sterilized because it is just water and glycerin.

Why would you want to use a cryopreservative that isn't sterilized? I mean, yeah, you might get away with it, but why take chances with your yeast bank? We always autoclaved the glycerine in my lab days.