Over night mash..

[foxy]

https://beerandbrewing.com/split-up-your-brew-day/

 

[lancon]

http://www.fermentarium.com/homebrewing/brewing-beer/shorten-your-brew-day-with-overnight-mashing/mentions possible off flavours, the temp would have to drop quite a lot though. I don't think it is a worry unless your temp drop is immense combined with extra long time in tun and yet again where would the infection come from?

 

[pilgrimhudd]

http://www.fermentarium.com/homebrewing/brewing-beer/shorten-your-brew-day-with-overnight-mashing/mentions possible off flavours, the temp would have to drop quite a lot though. I don't think it is a worry unless your temp drop is immense combined with extra long time in tun and yet again where would the infection come from?

The grain may have bacteria in it, I've always hoped I'd find that mould that causes hallucinations that did for everyone at Salem.

 

[foxy]

http://www.fermentarium.com/homebrewing/brewing-beer/shorten-your-brew-day-with-overnight-mashing/mentions possible off flavours, the temp would have to drop quite a lot though. I don't think it is a worry unless your temp drop is immense combined with extra long time in tun and yet again where would the infection come from?

Lactobacillus bacteria, it comes from the grain and its a spoiler, boiling doesn't eradicate it because the brew is already spoiled.

 

[An Ankoù]

From what I read the mash water gets an off flavour from the bacteria if the mash water isn't hot enough. You can then boil off and kill the bacteria but the off flavour remains.

Never experienced that and if the mash water isn't hot enough, it won't do a saccharification mash. I strike at 72C which is round about pasteurisation tmperature anyway. Still, I'll see what Brulosophy has to say on the matter when I get a mo.

 

[pilgrimhudd]

Never experienced that and if the mash water isn't hot enough, it won't do a saccharification mash. I strike at 72C which is round about pasteurisation tmperature anyway. Still, I'll see what Brulosophy has to say on the matter when I get a mo.

I think its if your mash temp drops below 50.

 

[lancon]

http://www.fermentarium.com/homebrewing/brewing-beer/shorten-your-brew-day-with-overnight-mashing/is mentioned a possibility of off flavours but I think that would be a dramatic fall in temperature and an extended time, and again where would the infection come from?

 

[pilgrimhudd]

http://www.fermentarium.com/homebrewing/brewing-beer/shorten-your-brew-day-with-overnight-mashing/is mentioned a possibility of off flavours but I think that would be a dramatic fall in temperature and an extended time, and again where would the infection come from?

Grain isn't sterile and there is bacteria everywhere?

 

[An Ankoù]

Grain isn't sterile and there is bacteria everywhere?

True enough, put malted grain is raised to at least 100C for an extended period. The bacteria would have to get into it afterwards. Or the storage conditions would be a bit naff.

 

[lancon]

http://www.fermentarium.com/homebrewing/brewing-beer/shorten-your-brew-day-with-overnight-mashing/this mentions possibility of off flavour but I think that it would need much lower temperature, longer time and a source of infection which if present in the mash would just as likely be around post boil.

 

[lancon]

sorry posted that again.

 

[strange-steve]

Malted grain is full of lactobacillus, some strains of which will not be pasteurised at mash temperatures (hence why a quick post-mash boil is recommended when kettle souring). Some of these may get enough of a hold to produce lactate or other off-flavours given enough time, particularly if the temperature drops below 50° or so, and although the boil stage will kill off the bacteria it won't get rid of those off-flavours. Admittedly, it's probably a very small risk though as long as the mash length isn't days.

 

[An Ankoù]

This is turning into a fascinating enquiry. I'm in spite of Steve's claim that some lactobacillus withstand mash temperatures, I'm still not persuaded. Certainly there are loads of lactobacillus on the grain and this means that we can have an acid rest at about 45C to reduce the mash pH or create acidulated malt. But that they are not destroyed at saccharification temperatures doesn't lie logically with the fact that we pasteurise milk in the UK by holding the milk at 72C for 15 seconds or, in other countries by holding it at 63C for half an hour. The bacillius don't become active again when the milk cools down so why should it do so in the mash. A typical saccharification mash is held for at least 60 minutes at between 64 and 68C or even higher. I suppose that if one of our number had a microscope or some culturing kit, he or she could solve this once and for all.
The second interesting side to this is why are the bacteria not destroyed and the enzymes in the malt denatured during the kilning process, where the temperature rises well above pasteurisation temperatures, and for longer. I suppose it has something to do with dry heat and wet heat.
There is certainly a difference in odour in a mash which has taken all night. It's not unpleasant or sour, just doughy and it's not carried across to the beer. I wonder if any perceived difference in flavour might be due to physical changes in the mash rather than biological ones. Gluten might be degraded or more tannins leached from the husks or something else, which needs a more prolonged soaking. In the meantime, I'm going to have a look at this Brulosophy article.
Right, I've read it:
http://brulosophy.com/2018/01/08/mash-length-overnight-vs-60-minutes-exbeeriment-results/and this one:
https://beerandbrewing.com/split-up-your-brew-day/Neither a very conclusive and I wonder about the point of the Brulosophy article and why they don't come clean and say there's no discernable difference.
There seems to be a concern that the mash temperature should remain constant throughout the whole period and I don't see why, as long as the saccharifiication rest is long enough for complete conversion then why shouldn't the temperature deteriorate? Those enzymes which have been denatured on the way up are not going to kick in again on the way down and once the lower limit of beta amylase, about 60C has been passed, any remaining di- and tri- saccharides are safe.
Nope. unless something else pops up, I reckon overnight mashing is as sound as a pound.

 

[strange-steve]

This is turning into a fascinating enquiry. I'm in spite of Steve's claim that some lactobacillus withstand mash temperatures, I'm still not persuaded. Certainly there are loads of lactobacillus on the grain and this means that we can have an acid rest at about 45C to reduce the mash pH or create acidulated malt. But that they are not destroyed at saccharification temperatures doesn't lie logically with the fact that we pasteurise milk in the UK by holding the milk at 72C for 15 seconds or, in other countries by holding it at 63C for half an hour. The bacillius don't become active again when the milk cools down so why should it do so in the mash. A typical saccharification mash is held for at least 60 minutes at between 64 and 68C or even higher.

I'm no scientist so I'm basing this on what brighter people than me have said. Milk the Funk say "the temperatures that a typical mash out/sparge are not enough to completely pasteurize the wort. Therefore, the best approach is to heat the wort for a short boil (1-2 minutes) in order to kill a greater degree (2-3 logs more) of thermotolerant microbes" and if you have a look at their sources 5 to 10 on this page they link several scientific sources that I admittedly have only just skimmed through, but to pull an extract from one:

During the mashing of malt, the microbial load diminishes, but thermotolerant microbes, especially homofermentative LAB, remain active in the nutrient-rich, high-moisture environment. Bacterial growth during mashing can have beneficial consequences, and mash acidification by lactic acid bacteria can improve the extraction, fermentability, and nitrogen yield of wort and the foam stability, color, and flavor of beer. The beneficial effects of mash acidification are achieved in most breweries by direct acid addition, but microbial acidification remains the only acceptable means for mash acidification in breweries adhering to the Reinheitsgebot German beer purity law. Bacterial growth can also cause serious problems during extended mashing. For example, Bacillus spp. can cause excessive acidification and nitrosamine formation by reduction of nitrate to nitrite. Growth of Clostridium in the mash or in wort can produce high levels of butyric acid, giving the beer a cheese-like aroma.

With regards to your milk analogy, don't forget that pasteurisation is not sterilisation and pasteurised milk will eventually sour, but Sour Beer Blog also address this question here with some possible explanations and the conclusion that "mashing alone is simply not enough to sanitize wort."

That being said though, I will restate that I do believe the risk is small and I have overnight-mashed several times with no ill effects.

 

[Gerryjo]

I know that when I do an overnight mash and forget to empty the mashtun after draining and has been left for a few hours it takes on an acrid sour note that is pungent and gets worse the longer you leave it.
When I do an overnight mash now I'm sure to get it cleaned ASAP and give it a damn good cleaning afterwards.

 

[dwhite60]

I wouldn't be able to sleep. Just the way I am.

Once I've mashed in that ninety minutes is mine. I can get plenty done so the time to me really doesn't matter that much. I'm doing BIAB so I'm not spending time lautering either. Bag comes out, heat goes up.

 

[PhilBrew]

With regards to your milk analogy, don't forget that pasteurisation is not sterilisation and pasteurised milk will eventually sour, but Sour Beer Blog also address this question here with some possible explanations and the conclusion that "mashing alone is simply not enough to sanitize wort."

... I'm not sure that An Ankou was suggesting that pasteurisation was sterilisation though Steve, nor that mashing alone is sufficient to sterilise wort ... but even if he did think that (I'm sure he'll clarify his thinking) I think the milk pasteurisation analogy is valid ... yes, pasteurised milk will sour eventually, but that will take a significantly longer than it would with unpasteurised milk, because that pasteurisation process will reduce the bacterial population to levels where it will take them much longer to create enough products to breach taste thresholds

So, to come back to the overnight mash question ... all this discussion looks like it's coming to the conclusion that both for enzyme activity reasons (not wanting to end up with a more fermentable wort than desired) and for anti-bacterial reasons (wanting to minimise the population of beer spoiling bacteria) it's really important that your mash tun is able to maintain your mash temps for as long as possible ... but that so long as it's able to do that for an hour or so, and only lose around 1C per hour (or less) after that, then that should be enough to both restrict enzymic activity to alpha-amylase only after the first 30-45 mins, and bacterial activity below beer spoilage levels for the duration of the mash & sparge

Cheers, PhilB

 

[An Ankoù]

I'm sure he'll clarify his thinking

Just drawing off a fourth pint to clarify my thinking and hope to have achieved a laser-point focus on the issue before I turn in, but it's going like this.: Strike the mash at 72C, which, for me levels out at an initial mash temp of about 64C. Keep the top of the cooler box nicely covered with a folded towel as there's no insulation in there. Fifteen minutes later, after everything has settled down, bring the mash up to required temperature with boiling water. Mash it all up nicely to make sure it's even throughout, put the lid on, cover with folded towel and forget it. Draw another pint and give yourself a pat on the back in the knowledge of a job well done. Wriggle into jimjams and draw a final "one for the road" to ensure you sleep the sleep of the just (as opposed to the sleep of the just married).
Wake up at the crack of dawn to the sound of Nina Simone belting out "Feeling Good". Cup of tea and down to business! If you're still fretting over enzyme activity and bacterial spoilage issues then you didn't take the previous nights "draw off another pint" sufficiently seriously. Resolve to do better next time.

 

[strange-steve]

... I'm not sure that An Ankou was suggesting that pasteurisation was sterilisation though Steve, nor that mashing alone is sufficient to sterilise wort ... but even if he did think that (I'm sure he'll clarify his thinking) I think the milk pasteurisation analogy is valid ... yes, pasteurised milk will sour eventually, but that will take a significantly longer than it would with unpasteurised milk, because that pasteurisation process will reduce the bacterial population to levels where it will take them much longer to create enough products to breach taste thresholds

So, to come back to the overnight mash question ... all this discussion looks like it's coming to the conclusion that both for enzyme activity reasons (not wanting to end up with a more fermentable wort than desired) and for anti-bacterial reasons (wanting to minimise the population of beer spoiling bacteria) it's really important that your mash tun is able to maintain your mash temps for as long as possible ... but that so long as it's able to do that for an hour or so, and only lose around 1C per hour (or less) after that, then that should be enough to both restrict enzymic activity to alpha-amylase only after the first 30-45 mins, and bacterial activity below beer spoilage levels for the duration of the mash & sparge

Cheers, PhilB

I'm not sure where the disagreement is, that was exactly my point in my first post when I said "these may get a hold... given enough time, particularly if the temperature drops below 50° or so". I wasn't suggesting that a typical overnight mash was long enough, but it could be if left for a longer period.

 

[PhilBrew]

Hi Steve

I'm not sure where the disagreement is

... Thanks for clarifying ... and I apologise for mistaking your stance in the discussion, I think I felt you were referring to that Sour Beer Blog post as reasons why this method shouldn't work (with your "admissions" to having performed overnight mashes in the past, coming from an "I got away with it" viewpoint) ... that post reads different now :tinhat:

Re-scanning the thread though, I get the impression what we've got is a number of people commenting in the thread who have performed overnight mashes, with no real issues and some slight improvements in efficiency ... and other people contributing who have never tried it, but have heard/read something/been told by a bloke in the pub mostly about the risks involved, all of which can be mitigated by making sure your mash tun is well insulated

Cheers, PhilB