Thick or thin mash?

Discussion in 'General Home Brew Equipment Discussion' started by Clint, Feb 12, 2019 at 2:35 PM.

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  1. Feb 12, 2019 at 2:35 PM #1

    Clint

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    With interest I'm looking at the Robobrew thread and started thinking about mash thickness. It needs more water in the automated system due to the dead space...fine.In my cooler I use less water resulting obviously in a thicker mash.
    In my instance does the thickness make a difference other than to how much sparge water you need to reach pre boil volume?

    Cheers

    Clint
     
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  2. Feb 12, 2019 at 3:16 PM #2

    Bigcol49

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  3. Feb 12, 2019 at 3:32 PM #3

    the baron

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    In my opinion it makes no difference Clint I have tried the recommended mashes of 2.6ltrs and have settled between 4 and 4,5ltrs. It does help with stuck sparges and it still leaves 12 to 14 ltrs to sparge with for the preboil of 28ltrs. I do not put too much emphasis on sparging and just do a simple jug sparge over the grains having put the top mesh on my system to dissipate the flow from the jug. I still get about 75% brewhouse efficiency which is good enough for me and do not strive to sparge it to death for a few extra points as my time is worth more to me than getting the ultimate efficiency
     
  4. Feb 12, 2019 at 5:03 PM #4

    cushyno

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    I concur with @the baron. 4L/kg works well for me. All previous mashes have been fly sparged with widely ranging efficiencies between 63-80%, but last weekend I chose to batch sparge with two lots of 6L and a rest of 5 mins between each. Sparging was cut from 40 mins to about 15 mins. Still managed to hit about 74% efficiency.

    Those who do full mash BIAB still seem to get good efficiencies. I bet there's a Brulosophy xBmt on water/grist ratios...
     
  5. Feb 12, 2019 at 5:19 PM #5

    Ajhutch

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  6. Feb 12, 2019 at 7:22 PM #6

    MyQul

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    I mash at 2.5L/kg. This is supposed to be an 'English mash'. I use it as I mostly make English beers. Whether it makes any difference, I have no idea, but it works for me.
     
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  7. Feb 12, 2019 at 7:48 PM #7

    peebee

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    I was reading somewhere (not Brulosophy) about comparing a mash+sparge with a "full boil mash" (mash with full brew length and therefore no sparge). The article complained the "full boil mash" resulted in very low efficiency and so the resulting beer scored low in the tests (alcoholic tasters?).

    But … with the Grainfather system you need a fairly thick mash (the recommended 2.7L/Kg works well) because the "top-plate" relies on the thickness to support it. Unless you apply kludges (I fix the top-plate with a jubilee clip). My last GF brew was a "full boil mash" at 7L/Kg, but as it was an unusual methodology ("low-alcohol" brewing) I have nothing to compare it with to say whether thin mash is better of worse. Thin mash was a hell of a lot easier, so with that biased view I'd say thin was very much better.
     
  8. Feb 12, 2019 at 7:55 PM #8

    stz

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    I'm going to say ... ignoring any variables regarding the mash tun, lauter tun, filtration, grist composition etc ...

    Mash thinness influences efficiency and enzyme activity. The thicker the mash the greater proportion of enzymes are present and thus the more concentrated they are in comparison to a thinner mash. They are also slightly better protected from the denaturing impact of the strike liquor. This means they tend to work a bit quicker and for longer in a thicker mash. That said, starch solubility is increased in a thinner mash meaning that while the enzymes are more dilute and are exposed to more hot water they have the chance to impact upon a greater overall proportion of starches meaning they work a bit harder for a shorter time in a thinner mash. The overall outcome is thus very similar.

    That said. Thinner mashes are more efficient at normal temperatures. More starch goes into solution. They are more thermally even and stable and require less extreme strike temperatures to hit higher mash temperatures. They are easier to run off. While there are a few instances where you don't want or need this, under normal circumstances my preference is for as thin as will fit into the mash tun, up to 3L/kg. When don't you want to do this? Usually when it won't physically fit in the mash tun. Usually when you want to do everything you can to reduce attenuation without going warmer than 68C. Equally though a shorter mash, a stepped mash and/or a mash out stage are valid techniques. I rarely go lower than 2.7L/kg.

    I'm going to come out and say though grist composition, yeast selection and fermentation profile is FAR FAR FAR more important to me than the final gravity achieved through mash temperatures. Mash is pretty much an efficiency, not a flavour thing for me.
     
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  9. Feb 12, 2019 at 7:59 PM #9

    stz

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    Also need to add based on reading some of the replies above that 85-86% efficiency is about where I'm at. The thinner your mash the less sparge liquor you'll have and generally, the lower your efficiency.
     
  10. Feb 12, 2019 at 8:02 PM #10

    peebee

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    Good point. I always discount the deadspace so the thickness figures I quote represents the water actually mixed with the grain. Including or excluding the deadspace is a pain if using "Beersmith" because it (at time of writing) is inconsistent about it.

    Not a lot of people know that (to repeat a famous misquote). I only know it because I'm an incurable tinkerer (or, as my partner prefers to put it, I fart around a lot).
     
    Last edited: Feb 12, 2019 at 11:36 PM
  11. Feb 12, 2019 at 8:24 PM #11

    Hoddy

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    You are correct. Mash thickness (recommended between 2.5 - 3.5) affects your mash efficiency because it does affect how far the enzymes have to travel to effectively convert the proteins and starches in the mash. Too thick and the enzymes are not able effectively carry out that conversion. To thin and the ezymes are diluted and are unable to work as efficiently to get to work across your whole mash.
     
  12. Feb 12, 2019 at 9:03 PM #12

    Martybhoy

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    I do BIAB brews. I recently tried full boil mashes and my mash efficiency changed not a jot. So I have stuck with this in order to shorten the brew day.

    My mashes now are approx 6 or 7ltrs per kg. Very thin I know, but I haven't noticed any difference come drinking time. If you miss your strike temperature it can be difficult to fix with the volume of water already in the kettle, but rarely an issue.
     
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  13. Feb 13, 2019 at 5:53 PM #13

    BeerCat

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    For a 5kg grainbill I use 20l and sparge with another 20l.
     
  14. Feb 14, 2019 at 12:12 PM #14

    peebee

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    I'm going to argue with that, but at the same time "liking" the post for the rest of it's content. The grounds for disagreeing are based on some pretty extreme brewing though.

    Preceding the post in question I had a post extolling the virtues of a "full boil mash". It added up to 7L/Kg and with just over 4Kg of grain (including 1Kg oat husk, 'cos half the total grain bill was rye malt) it was pretty near full for a Grainfather. The mash was 73C! The result was a "beer" of about 1.4% ABV yet a final gravity of about 1.016. Obviously in that case the final gravity achieved through mash temperatures was FAR, FAR, FAR, more important for flavour (mouth-feel at least) than anything else.

    But the rest of his post did seem to support the use of "full boil mash" in my case.
     
  15. Feb 14, 2019 at 12:45 PM #15

    HarryFlatters

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    In my mind, if you BIAB the mash is artificially held more densely together by the bag, so would that enzyme stuff @stz wrote about be affected by the water undeneath? I've no idea.

    In my (very) limited experience, I've always filled my Peco as high as it'll go, with minimal sparging, so I have fewer vessels in which I have to treat water. I'm only doing that to make brewdays as easy as possible in total ignorance of the chemistry that's happening.
     
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  16. Feb 14, 2019 at 1:28 PM #16

    Sadfield

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    Mash thickness for me is about the practicalities of the system. I tend to vary it in order to keep a good level in the cooler mash tun. Brewing beers in a range from 0.5 to 10% ABV makes maintaining a set water to grain ratio, near on impossible. I don't find it makes a dramatic difference in the end product.
     
  17. Feb 14, 2019 at 7:17 PM #17

    stz

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    You can do full boil mashes if you want? No body is going to stop you. These things are often about what pushes the overall outcome in what direction. The enzymes present will be more dilute and rapidly exposed to hot water. if this water is over conversion temperature they will quickly denature resulting in a less fermentable wort than a comparable thicker mash with the same temperature stand. There would be a minor difference in the beer. This is just one variable though. The starches present will indeed be super soluble, but in such an extreme case you'll still generally promote a less fermentable wort, varied by the total diastatic potential of your grist. Either way this is just another variable and again about pushing in an overall direction depending on goals. They contradict each other, but in certain scenarios they make a difference. It depends on what you are trying to do. It is more commonly like "I'm trying to make this beer finish high, so I'm going to mash hot, but not as hot as I usually would, because I'm also mashing thin due to it being a glucanous grist, lots of proteinous muck, I'm concerned about the run off ruining my life". You give it your best shot and then you move on to the next brew. Like I said though, 2.7-3L/kg as thin as will fit into the mash tun (within that range).

    Your efficiency will be severally compromised by the lack of sparge. No sparge methods typically get 60% efficiency. Don't get me wrong, the high temperature is absolutely the main reason your brew finished at 16. The poor extract you experienced is because of no sparge. The thinner the mash, the shorter the sparge for a comparable volume.

    For the heck of it we can work back from your brew. 1.4% abv is 10.68 points fermented. Add your final gravity of 16 ... starting gravity of 26.68. Assuming 3kg of malt as the husks have no extract 900 total potential extract, over 22 litres (assuming!) 40.9 potential at 100% efficiency, 26.68/40.9 ... 65.21% efficiency. Yeah par for the course assuming your batch size was 22L. 59% if it was 20 litres. If it works for you cool. I personally wouldn't even want to think about controlling mash pH, phenol extraction and other details in such a scenario.

    What I mean about flavour and stuff is this ... if you are mashing outside of 64-68C without a very specific reason you are generally doing it wrong. This is with the caveat that I'm talking commercially. It is all about efficiency. If you want a higher or lower final gravity you don't mash outside of this range, you reach for another yeast or you alter your grist composition. Final gravity has an impact upon body, but you'd be REALLY REALLY REALLY surprised at how hard it is to detect differences in specific gravity. 1.100 is 10% denser than water. I meet people who claim to tell the difference between 1.001. This is a 0.1% difference in density and ... just complete rubbish. The amount of time lost where progress could be made because people hold on to these old ideas like "hmm, this brew is nice, but it could be a little higher in body and sweetness, lets increase the mash temperature by quarter of a degree next time" then they stand there and claim it is now perfection because it finished at 1.009 instead of 1.0088 or something similarly within the realm of a read error and they are drinking the wrong damn sample anyway.

    Dextrins are flavourless carbohydrates. There is a little sweetness from them on the finish as the glycosidic enzymes in your saliva break them down into simpler sugars you can actually taste, but by themselves they taste like sand. They do lend body and a sensation of fullness, but again, you'd struggle to detect less than 7 points of them, sometimes 15. So many very popular (awful) commercial beers are super attenuated. Dextrins are an enemy of stability and sessionability because they make you feel full up (and fart). Mashing hot to the point where you have enough dextrins to make a beer thick and sweet is just ... banging your head against a brick wall, use a more flavourful base malt, reduce the carbonation, bias the beer towards chloride, add some sodium even, take out some of your bittering hop, think about some caramel or crystal malts, million ways to make it work, but no ... lets just increase the mash 0.25C when we brew it again sometime next year that'll do it I'm sure the ambient temperature won't throw it off anyway and the mash tun has a stable and homogenised temperature and our probes are calibrated and accurate to that degree, sure.
     
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  18. Feb 15, 2019 at 12:59 PM #18

    peebee

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    Cor. That took some stamina to read! Guess it took more stamina to write?

    But I was just playing devil's advocate, and I wrote about my "trials" in low alcohol brewing. And because I'm well aware that small parameter changes will most likely be undetectable, except to vivid imaginations, I was messing with pretty extreme changes of parameters.

    But the moral wasn't about beer at all. I was just making the point - don't make generalisations out to be fact, because there is always someone, somewhere, not being "generalised" ...

    (No criticism; I've not long figured it out myself as a result of using these forums).

    Your assumptions seem about right. I got (Beersmith) a brewhouse efficiency of 55% and an attenuation of 41%. Brewing "low alcohol" actually encourages aiming for pretty poor conversion figures.
     
  19. Feb 15, 2019 at 1:23 PM #19

    Clint

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    Ironic really when there's acres of ramblings on not hitting OG or missing it by a spine crumbling 2 points...and like said in reality no one could tell the difference. I suppose being that worried only worries those making money out of it...
     
  20. Feb 15, 2019 at 2:17 PM #20

    Brightonnik

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    That's spot on I feel, on the scale that we brew as homebrewers make beer I would challenge anyone to be able to duplicate a recipe but with one purposely miss gravity by 2-5 points a d be able to notice a difference in the end product.

    Regarding the robobrew I couldn't recommend it highly enough for the money that you pay it is a great piece of kit.
     

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