Overnight mashes... pros and cons?

[NickW]

Hi all,

I'm all for saving time on brewday but I don't want to sacrifice quality... are there any cons to overnight mashes? Perhaps the production of more short strain sugars?

 

[rpt]

As long as the temperature stays above 50C they are great. Below this and bacteria gets a chance to make some off flavours.

 

[keith1664]

The few times I've done them the FG has been a fair bit lower than for a standard length mash, not really a problem if you're aware of it.

 

[NickW]

The few times I've done them the FG has been a fair bit lower than for a standard length mash, not really a problem if you're aware of it.

This.

This is what I don't want to happen.

If I'm making a sweet stout or a more full bodied beer, I don't want my 68c mash temp nullified by an overnight mash.... it sounds so convenient though

 

[dennisking]

Only done it twice, both times achieved a slightly higher efficiency, but also got a stuck mash.

 

[jonnymorris]

FG? I assume you mean OG and if so, I find the opposite, i.e. a better mash efficiency and therefore higher OG (which you can easily account for beforehand in the recipe).

I've done 7-8 over-nighters now and swear by them. Not aware of any downsides... wait... raising the temperature of the mash if you want to do a mashout can be tricky. I think that's about it.

 

[NickW]

FG? I assume you mean OG and if so, I find the opposite, i.e. a better mash efficiency and therefore higher OG (which you can easily account for beforehand in the recipe).

I've done 7-8 over-nighters now and swear by them. Not aware of any downsides... wait... raising the temperature of the mash if you want to do a mashout can be tricky. I think that's about it.

I think he did mean FG. This would imply more shorter strain sugars being extracted , resulting in a thinner beer.

 

[jonnymorris]

I think most conversion happens in the first hour or two so I don't think that's an issue. At least, in my experience, I generally mash high for sweeter beers with more mouthfeel and never have that problem with my over night mashes.

 

[pittsy]

The problem as Nick mentions could be when using a high temp mash for eg 71c for a really full brew but left for a long period at 71c and the longer chain sugars (full bodied ) will be chopped up to make shorter sugars (thinner bodied ) so a lower FG will result ( not so much apparently if mashed at say 66c or so folk have mentioned :hmm: )

 

[NickW]

I think most conversion happens in the first hour or two so I don't think that's an issue. At least, in my experience, I generally mash high for sweeter beers with more mouthfeel and never have that problem with my over night mashes.

Interesting! I may try one for my next brew.

Wasn't planning on brewing this weekend due to other commitments but I could very well squeeze in an overnight mash... I just hope my mashtun wrapped in a blanket will be able to hold it above 50c..

 

[keith1664]

FG? I assume you mean OG and if so, I find the opposite, i.e. a better mash efficiency and therefore higher OG (which you can easily account for beforehand in the recipe).

I've done 7-8 over-nighters now and swear by them. Not aware of any downsides... wait... raising the temperature of the mash if you want to do a mashout can be tricky. I think that's about it.

No, I meant final gravity. For example a beer with an expected FINAL gravity of 1.012 ended up at 1.008.
It was a bloody lovely beer though and it wouldn't stop me overnight mashing again.

 

[Jeltz]

I have just changed from overnight mashing with BIAB to a 90 minute mash and 3 vessels. The reason being that I suspect that it produces a more fermentable and slightly thin beer. I've produced wort with a higher OG and lower FG than I would have expected, great for higher ABV beer but I'm after body now.

My reading has suggested that both the looser grist ratio and the long mash might have contributed to the lack of body. Not that the beers have been bad just that they might have been better done another way.

I guess time will tell.

 

[rich27500]

I love overnight mash except I do mine overday, put it on before work boil it when I get home. Beers are too similar to tell the difference and the only stat I really go by is taste.

 

[graysalchemy]

I have been finding that some of my beers are thinner but then I have been struggling to get my mash above 66c. I was planning on mashing much higher 69-70c ih hope that this would compensate for it.

It seems to be fine for my pales but it is noticeable in stouts, though not a problem in high ABV malty beers where in actual fact you usually mash at a lower temp to avoid cloyingly sweet beer.

:thumb:

 

[adomant]

I don't get it myself, the only reason appears to be to save 90 minutes on a brew day (understandable if you really are that short of time. It does not make for better beer, in fact could introduce some problems and the efficiency gains are not substantial (nobody does it commercially).

If I want to get an early start, I preload my mash tun for underletting the night before and set a timer/PID on the HLT so all I got to do is let the water in and stir. I use the 90 minutes to walk the dog, prepare the sparge water and other tasks for the rest of the brew day.

I sometimes use herms to step the temperature up in order to control the profile of the fermentables and I'm not brave enough to leave that overnight, so that could be why I don't consider it.

If it works for you and you have a tight brew day then I see no strong reason not to do it I guess

 

[hairybiker]

No it isn't just 90min. You have the heating time for the liquor as well, add another 30 min or so, then the mash in process 10+ min, so more like 2-3Hours.

 

[graysalchemy]

Also the bigger the volume you brew the longer the sparge so saving 2 hrs on the day is a great saving, especially if you have other commitments or a specific time frame.

My efficiencies are also much greater at least an extra 10%, not that that is a selling point to me. :thumb:

 

[morethanworts]

If you mash in a coolbox or other well insulated tun, it's the one bit of the process where you can go and do something else completely for 90 mins or whatever. I'm only on AG3, so I still make use of that time checking what I'm doing and making sure everything is ready for for the sparge onwards.

I can't see where I'd save much time by overnight mashing. I guess the brew day itself would end an hour or two earlier, but the mashing in etc would have been time spent the previous evening, and the mash time itself is time I can use anyway.

 

[rpt]

Overnight mashing doesn't necessarily save time but it can make it easier to fit brewing around the rest of our lives.

 

[morethanworts]

Overnight mashing doesn't necessarily save time but it can make it easier to fit brewing around the rest of our lives.

:thumb: I guess it depends on your own schedule.

It's the sparge onwards that I need to get much shorter myself.