How Long To Boil To "sterilize" It ?

[Maheel]

if i mash in all grain BIAB with the intention to no-chill it in a cube how long would i need to boil it for to avoid an infection?

disregarding hop's

eg BAG out then boil for X then cube it.

would 20 mins hard boil do it? or less or more with lid on?

 

[Wolfy]

Hard or gentle boil, lid on or lid off, you are still only going to get the wort to 100C so the real factor will be how long you boil for.

Tyndallization requires 3x 15min boils to ensue sterilization, however, it should be fair to assume that boiling for 15mins should kill any bacterial cells in the wort.

 

[amiddler]

From all that I have read, I agree with Wolfy. A 15-20min boil should see the wort sterilized.

Drew

 

[[email protected]]

What are you brewing with no bittering hops? Just bringing it to the boil should be enough. Wort boils at around 105C and it will be well over 70 C for a few hours. If something can survive that then you should be more impressed then angry with it for ruining your beer. But better to be safe and give it a good 10-15.

 

[michael_aussie]

.........
Tyndallization ........

Putting aside brewing, I have learnt some great stuff at this web site.
One of my loves of home brewing is the way it has expanded my general knoweldge about so many diverse things.

And most of that is thanks to you guys.. like Wolfy!! ty

 

[MHB]

There are lots of reasons to boil a wort other than just sterilisation, if that is your aim then something like 15-20 minutes would suffice. As mentioned above the long period of time spent in the cube cooling from near boiling to 60^oC is where most of the pasteurisation occurs.

Boiling also removes excess protein, and a bunch of other products that we want out of the beer (here is a link to some very good resources).

Paxxy, that figure of 105^oC is way off; a 1.050 wort will have a boiling point of only 0.1^oC higher than water still hot enough to sterilise but at the temperature you suggested we are talking about making fudge, Wiki link.

MHB

 

[Hatchy]

There's other reasons for a minimum of an hour boil apart from hop utilisation & sanitation. Some sort of nasties get boiled off in an hour boil that will survive a 20 min boil. I'm sure someone will post here to tell me what I'm talking about.

 

[[email protected]]

Paxxy, that figure of 105^oC is way off; a 1.050 wort will have a boiling point of only 0.1^oC higher than water still hot enough to sterilise but at the temperature you suggested we are talking about making fudge, Wiki link.

MHB

I apologise for spreading mis information. I guess I was told it by someone and it seemed plausable, especially given the high temperatures required to make candy sugar and never measured it for myself.... glad to be corrected.

 

[Thirsty Boy]

Not wanting to dredge up a very dead horse to flog, but....

Botulism

No chilling worts is very unlikely to give you botulism despite the fact that cubing up hot, deoxygenated, nutirent rich substrate would seem to be asking for it to pop up its head and kill you.

Some of the reasons it doesn't are -

Low pH in the wort - and the longer you boil, the more the pH drops. Not a lot, but more.
LONG - boiling times, not just enough to kill actual bacterial cells, long enough to do for most spores as well
The presence of iso alpha acids from hops - the gram negative (its negative for botulinium right?) bacteria are really not happy about iso-alpha acids and it stops them from growing.

So if you only boil for 20 mins and with no hops.... Then you are removing or reducing basically all of the things that make botulism so unlikely in no-chilled wort.

I'm not saying that it actually likely that botulism will be an issue - but with a short no hops boil and then no-chill, you would be taking away a lot of the things that make it unlikely.

 

[Florian]

hhmmmmm...

How much hops is needed?

Just thinking about my next two brews:

-Berliner Weisse with 15 Minute boil and only 3-6 IBU
-20L unhopped wort no chilled in 2L containers for yeast starters (at least I got a long boil)

 

[Thirsty Boy]

Yeah - something to think about for sure. You are in the category of "it'll almost certainly be ok" its not like the risk is high or anything, just not as "not high" as it could be.

Me personally - i would either boil the berliner properly or chill it (throw the cube in the pool or something if you dont have a chiller) - and the unhopped starter wort that you will presumably be leaving stored for a long period of time.... I'd hop it to 10IBU or so and give it a good long boil, or I just wouldn't do it.

Its a risk assessment thing. There isn't much chance of anything going wrong, but the consequences of the thing that might go wrong (botulism) are quite likely to be fatal. And you can mitigate those risks almost entirely with small changes with few negative consequences of their own - i'd make the changes.

 

[Florian]

Thanks for that info.

Not sure if I trust the pool to cool it down quick enough (although it should probably alright), so I might dig out the old copper coil and give it a good dusting. At least the BW ferments relatively warm anyway so I should get pretty close with Brisbane tap water. I would assume that if I was to do a sour mash (which I haven't planned this time, but possibly next time around), that this would help as well as I'm bringing the pH down.

Can't really chill the starter wort as I wouldn't be able to keep it for long then, so will do as you said and give a bit of a bittering addition early in the boil. Had planned a 90 minute boil anyway as it will be be a light pilsener malt.

 

[felten]

When I made my berlinner I didn't cube it (I didn't boil it either, just mashed out at 80c), just threw it into the fermenter hot and pitched the lacto when it got down to mid 30's. Then pitched the yeast after 12hr or so when it had cooled to pitching temps.

 

[Maheel]

appreciate all the info,

thanks TB for the thoughts on Botulism, what sort of time frame would Botulism need to take hold?

intention was to make two 13L batches, boil a bit longer say 30 mins
no-chill overnight, throw in fermentor next day once "cool"

i might speed up the cooling by chucking it in the pool

 

[RobW]

Boiling is unlikely to kill botulism spores, it normally requires a combination of highter temperature and pressure.
In fact Clostridium spores (botulism is caused by Clostidim botulinum) are commonly used to test the performance of autoclaves.
Nevetheless if your brewing practices are satisfactory you will kill off any vegetative forms in the boil and the subsequent risk of infection is negligible.
There are many more common bugs which can infect your beer and if you are not having problems with infections in general I'd rest easy.

 

[Thirsty Boy]

Long boiling times in the low pH environment of wort can kill botulism spores, and certainly does over the vegetative form. Pressure in an autoclave simply allows the temperatures to be higher and higher temperatures mean shorter times for a given kill rate - you can replace the higher temeprature with a longer time. And in terms of bug killing regimes, a full hour or longer at the target temeprature is a pretty long time.

At any rate, its not so much the notion of a shorter boil on its own that worries me, its the shorter boil AND lack of hopping that would really make me concerned.

Maheel, it could happen in a few weeks, it could happen overnight - the risk is low, but it is not as low if you take shortcuts, and the results of it not working out could be drastic.

You can do it if you like, and in all probability you'll be perfectly fine - but i wouldn't do it.

 

[RobW]

Long boiling times in the low pH environment of wort can kill botulism spores, and certainly does over the vegetative form. Pressure in an autoclave simply allows the temperatures to be higher and higher temperatures mean shorter times for a given kill rate - you can replace the higher temeprature with a longer time. And in terms of bug killing regimes, a full hour or longer at the target temeprature is a pretty long time.

At any rate, its not so much the notion of a shorter boil on its own that worries me, its the shorter boil AND lack of hopping that would really make me concerned.

Maheel, it could happen in a few weeks, it could happen overnight - the risk is low, but it is not as low if you take shortcuts, and the results of it not working out could be drastic.

You can do it if you like, and in all probability you'll be perfectly fine - but i wouldn't do it.

TB - sorry we'll have to agree to disagree on boiling to kill spores :icon_cheers:

Here's a reference:

http://edis.ifas.ufl.edu/fs104

but in any case I believe the whole botulism in beer argument is a crock, it's just not an issue.

 

[unrealeous]

but in any case I believe the whole botulism in beer argument is a crock, it's just not an issue.

Extremely unlikely, but not zero.

The only time I get worried is when I hear of no-chiller's having a swollen cube (ie definite unknown infection) but they say they'll ferment it out anyway to see what it tastes like. To me, that's just asking for trouble.

 

[Thirsty Boy]

I think the original question has been well enough answered - so from here on in anything i say is just for general interest on the topic i managed to wander the thread into, and for the sake of winning an argument...

If you want me to shut the hell up in the thread you started Maheel, just say so and I will desist/delete.

Here is a link to a nice reference with some actual numbers related to temperatures and kill rates for botulinium spores of various strains in various substrates. The link takes you to the wrong page (its a google books reference) so you need to scroll back to page 80 of the book and you get a bunch of tables with results from various researchers looking to find the time vs temp points where botulism spores are killed.

http://books.google.com/books?id=lxycHnaPf...wth&f=false

While not all of the studies look at temperatures as low as 100c you will see that for the ones that do - there is indeed a D value (the time required at the given temperature for a logarithmic reduction in the number of live spores) for even the heat resistant strains of botulinium. Its just that when you are talking temperatures of 100C the D value is anything up to half an hour or so - whereas at 110 it might be a minute or two and at 121 it coud be just seconds.

It's interesting to see that where the two were tested together, D values for things with a pH at around the level of wort (say 5.2 ish) were quite a bit lower at 100C and around 15-20 mins from what i could gather. Some studies looked at even lower temps, and you can see the drastic difference it makes, with a D time of 800+ minutes for one strain at 82.

Now my understanding of how this stuff works in the food industry (a far less than expert understanding, lifted in decent proportion from wikipedia) is that they are looking for a 12 x D reduction in order to be sure the food is safe, so 10 to the power of 12 less spores than before the heat treatment. And the reference value of D (at 121) is 12.6 seconds for C.Botulinium. Meaning that you get 12 x D in 151 seconds.

Now there is a fancy formula you can plug this stuff into to work out how long you need at lower temperatures, but as a rough rule of thumb, this stuff becomes 10times more or less effective for every 10C you raise or lower the temperature. So if at 121 you get 12D in 151 seconds (2.5 minutes) then at 110 it will take ten times longer and be 25min and at 101 or about where wort boils - 250minutes.

So to be fairly sure you had a safe product you would need to boil for a little more than 4 hrs. Which of course we aren't doing as homebrewers. BUT - that reference for D is for foods that have any old pH value... Wort on the other hand is relatively low. So if we go back to the tables in the link i posted and use that info to make the almost certainly incorrect assumption that things with a pH of 5.2ish have a D value around half what it would be at pH 7 - then the Reference value of D could be taken to be 1.25min and that would give you 12 x D in 125mins at 101C - which is more like something a homebrewer would do.

And of course, with no-chill, the wort is staying hot for a long time after you put it in the cube - you are still getting PUs in there as a few people have said. So altogether, it ends up working out that you have a pretty damn safe product if you follow the standard practise of boiling for an hour or 90 mins and cubing. Not to mention the fact that hopped wort is a fairly unfriendly place for the spores to try and grow into bacteria and start being dangerous.

But (in an effort to try and keep it vaguely related to the original topic) if you knock time out of the boil and rely on whats happening in the cube - well, remember the 10x multiplier. 45mins less at 100 in your kettle, is going to need (around) 450mins at 90 in your cube to have the same killing effect, and your cube is cooling down as it sits there. And if you were to then not have any hops in there..... That might just be asking for trouble. You probably still aren't going to actually get any trouble - but you are kind of looking the universe in the eye and inviting it to "have a go if you think you're hard enough mate"