I'm looking at brewing an all-grain barley wine in the near future, and I'm aiming for a high ABV (13%-14% ABV). From what I've heard in discussions elsewhere, by single-infusion mashing at a lower temperature (I'm shooting for 148 for about 90 minutes), I am extracting more fermentable sugars and achieving a dryer taste (both of which I want for this style ale). What are the less than desirable qualities in a barley wine that I will suffer as a consequence for mashing at the lower end of the scale? I'm mashing for 90 minutes instead of the typical 60 to try and guarantee I get the pre-boil gravity I'd like, but is 90 minutes excessive? Is there such a thing as mashing for too long? What are the consequences of mashing for "too long" (however long that may be)?

  • For temperature control I am using an electric serving tray. I have 2 at this time. One at maximum setting will hold the water in my 5 gal. pot at 165 and is adjustable down from there to what ever I want, at its lowest setting it holds at 130 The other one at maximum holds at 140 and can be reduced to 110. That amount of control requires a moderately controlled environment, aka not drafty. Of course a person is not going to be able to put a plastic mash tun on one of these, I use a stainless pot. Commented Feb 22, 2020 at 0:41

3 Answers 3


Yes, mashing for longer than 12 hours may not be good for the beer, particularly if the temperature is allowed to drop during that time. (As anyone who has left a mash for that length of time and taken a sniff will confirm!)

In this case with so much grain you could safely go for a 2 or 3 hour mash, to be sure of complete conversion. since the water to grist ratio is going to be lower (a thicker mash).

  • Have you ever tried an overnight mash? Say for 10-12 hours? I have and there's nothing wrong with it.
    – Denny Conn
    Commented May 8, 2013 at 15:13
  • If you can maintain the temperature then it's ok. I say 12 hours is ok in my answer. Sometimes I leave the mash in the MLT until the next day and then clean up - it doesn't smell good if it cools to 90-100F or so - I wouldn't contemplate using that in a beer - I don't really like vomit-smelling beer. :)
    – mdma
    Commented May 8, 2013 at 18:34
  • IIRC, I've gone up to 16 hours and the temp dropped to about the mid 140s. No off aromas, no problems. But like you say, if it smells bad, don't use it!
    – Denny Conn
    Commented May 8, 2013 at 19:06
  • 2
    Or, if it smells bad, let it go another day and then call it a Berlinerweisse! No joke, these beers are often made with a 2-3 day old 'sour mash'. You need a blanket of C02 in the mashtun to keep the nasty bugs out, but the corn/vomit smell does boil away completely when done properly.
    – GHP
    Commented May 9, 2013 at 17:07

With a barley wine isn't the major issue going to be sparging not mashing? Mashing is pretty straight forward, but getting that much sugar off that much grain is usually a pain. When I brewed an all-grain barley wine with a friend the mashing was easy. I think he used 90 minutes for mashing as well. Sparging took forever. With a fly sparge and using a refractometer checking the wort every 20 minutes it took us the better part of 4 hours. It was laborious to constantly be making new sparge water and we ended up with a 15 gallon boil for 5 gallons of beer. I think that sparging critical point for a barley wine.

One issue with sparging is getting too many tanins in the wort which will increase astringency. With a barley wine that is a serious consideration as you are milking all you can get out of the grain. Keeping the pH in a reasonable range (http://braukaiser.com/wiki/index.php?title=How_pH_affects_brewing) and not making the sparge water too hot (http://www.howtobrew.com/section3/chapter17.html).

  • I know people who do overnight mashes and don't experience contamination, so I had to downvote.
    – Denny Conn
    Commented May 7, 2013 at 15:31
  • 1
    I did once an overnight mash, not contamination but it got a low diacetyl-ish taste.
    – Geo Perez
    Commented May 7, 2013 at 20:32
  • I haven't ever mashed overnight because I have a hard time keeping temperature controlled enough for an hour or 90 minutes. So I shouldn't have said anything about that so took it out. But the comment about sparging still stands. Commented May 8, 2013 at 0:23
  • 2
    The goal of sparging a barleywine should not be to get every last molecule of sugar out of it. Boiling 15 gallons down to 5 is not a good approach -- a huge expenditure of time and propane. Instead, your recipe should use enough malt to get a reasonable gravity out of 7 collected gallons for a 5 gallon batch. If you have the time, equipment and inclination, you can continue sparging into another kettle-- this is known as "second runnings" and you can make a smaller beer (ordinary bitter, scottish ale, etc) with the wort you collect. Astrigency is only a factor when you oversparge.
    – jalynn2
    Commented May 8, 2013 at 17:54
  • When we did this we assumed 65% efficiency. So we had plenty of grain. It just took a lot of sparge water before the amount of sugar running off the massive amount of grains went below what we felt was a completed sparge. Commented May 8, 2013 at 19:25

Sometimes, when I mash too long (more than 90 minutes), I get a stuck-mash. Its as if my grain bed gels-up, like pudding or cold oatmeal. I have found that using rice-hulls or a more coarse grind can help reduce the effect.

If you do an iodine test (with idophor) you can determine if the conversion is done. Once it is done, waiting any longer won't make any difference.

I also have heard of something called "turbo-malt" that is supposed to be heavily modified and converts in under 40 minutes.

  • 2
    I have to disagree that waiting longer after a negative iodine test won't do anything. Longer mashes continue to break down long chain dextrins (which have already been converted from starch) and give you a more fermentable wort. The "myth" of short mash times comes from commercial operations. They may only hold a mash rest for 15-20 min. but they take hours to mash in or sparge and lauter. The grain is at mash temps all through those, so the they're actually mashing for much longer than the rest time they state.
    – Denny Conn
    Commented May 9, 2013 at 16:43

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