40-Minute Mash Time

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dmtaylor
dmtaylor's picture
40-Minute Mash Time

Okay, I'll bite... My first post here. And ain't it a doozy.

Early in my all-grain homebrewing "career" (about 6 years ago), in the interest of minimizing the length of brew day, which had been taking more than 5 hours and I only wanted maybe 4-4.5 hours, I ran a multitude of batches varying the mash time for each batch to determine the minimum mash time necessary to achieve adequate efficiency.

Well, the first thing I learned from my experiments was, if you mash for anything over like 20 minutes, efficiency isn't affected significantly at all. At the time I was seeing consistent efficiency of around 77% on average, regardless of mash time. Not a bad result, and not the one I had expected either...

What I did notice is that with mashes of less than 30-35 minutes, the fermentation would sometimes quit early, with an attenuation of only mid-60s in a lot of cases. This did NOT happen with every batch, and it did not happen with every yeast strain. I figure the odds of getting a good batch with good attenuation in the 70s or low 80s with a very short mash time are roughly 50/50. Seems difficult to predict from batch to batch.

The next thing I found was that if I mashed for at least 40 minutes, then every batch turned out spot on perfect with respect to both efficiency and attenuation. So, I have been mashing for 40 minutes pretty much ever since, except for those cases where I got lazy or distracted or purposely wanted a bone dry saison or something like that. But for about 90% of recipes that specify 60-90 minute mashes, I mash for only 40 minutes, and I get results that I cannot distinguish from what was intended.

Try it for yourself and see. Happy mashing. :)

denny
denny's picture
Dave, did you ever check

Dave, did you ever check conversion efficiency on some of those very short mash batches that didn't attenuate as expected?

Life begins at 60....1.060, that is!

Dr.Reddog
Dr.Reddog's picture
Temp?

I would be interested in further exploring the mash time/temp factor. The shorter mashes that didn't attenuate, what temperature were these mashed at? As I understand it, hotter mash temps gives you less fermentable wort. So I wonder if you could counter the attenuation effect of the short mash by mashing at a lower temp? It seems counter intuitive, but that would be interesting if you could get good results with less time and less heat.

denny
denny's picture
But hotter mash temps also

But hotter mash temps also give you faster conversion. I wonder if that somehow counteracts the supposed reduction in fermentability?

Life begins at 60....1.060, that is!

dmtaylor
dmtaylor's picture
My results were all over the

My results were all over the board. I brewed a total of 6 batches with mash times of 20 to 35 minutes. Mash temperatures were all between 147 to 152 F. The one batch (a specialty beer sort of like an old ale) mashed at 147 F for 35 minutes attenuated to 74% with Wyeast 1318. At another extreme, another batch (an apple ale) mashed at 150 F for 20 minutes attenuated to 75% with WLP400. Admittedly, the high fermentability of the apple cider might have carried this one farther than it would go otherwise. The worst attenuation was for a Sam Adams Boston Lager clone mashed at 151 F for 30 minutes -- I got just 61% attenuation with Wyeast 2308 on the 3rd generation. The other 3 batches fell in between with attenuations in the upper 60s to lower 70s. No clear patterns were observed. No, I never did run an official conversion efficiency test, and also I have never ever used iodine to test for conversion. I figure, if it tastes sweet and it attenuates well, then there's no need for these things. I found my magic number of 40 minutes mash time, and quit the experiment at that point.

Dave "This is grain, which any fool can eat, but for which the Lord intended a more divine means of consumption. Let us give praise to our Maker, and glory to His bounty, by learning about... BEER!" - Friar Tuck (Robin Hood - Prince of Thieves)

pjj2ba
"conversion"

Conversion is not a start and end process. One can get conversion such that there is no longer any iodine positive starch left in the mash, however, that doesn't mean that the process is over. It just means you've broken down all of the large iodine positive particles in the mash. There are still lots of dextrins in there that continue to get broken down into smaller and smaller pieces. That is a good candidate for why a shorter mash might not attenuate well

The higher the heat, the faster the "conversion" - that is the faster you will get a negative iodine reaction. However the wort will be very different from one mashed at a cooler temp. There really is no way around taking more time to get a more fermentable wort (short of adding extra pure enzyme, or perhaps including some 6-row in the recipe)

I brew a lot of lagers and like to do step mashes. I'll mash at 146 until I've got about 90% conversion and then ramp it up to 160 so the remaining starches get left as larger dextrins to add some body to an otherwise highly fermentable (low body) wort

erockrph
What's your mash thickness? I

What's your mash thickness? I've seen improvements in fermentability by increasing my mash times from 60 to 75 minutes. I recently had a few brews end up finishing higher than expected, so I bumped up my mash time and that seemed to solve the problem. I BIAB/no-sparge, and the brews that finished high were lower OG than usual for me (1.040's instead of my usual 1.060's ballpark). After seeing this thread I'm wondering if I needed some extra time because my mash was so thin.

dmtaylor
dmtaylor's picture
Until recently, I always

Until recently, I always mashed at about 1.3-1.4 qts/lb thickness. Now I mash a little thinner at closer to 1.8-2 qts/lb. I don't think this makes a significant difference in efficiency. I can get 90+% efficiency at either thickness. The main thing is the crush obviously, and a good sparge. If you skip the sparge, your efficiency will vary wildly.

I forgot to mention... for the experiments I ran for mash time, 2 batches were BIAB, and 4 batches were batch sparged. I always sparge with BIAB by pouring hot 180 F water over the grain bag while it sits in a colander. It is a tedious process, but for smaller batches (I always do 2-3 gallons) it is not so bad, and improves efficiency significantly, versus just squeezing the bag or dunking the bag in hot water. By pouring you are essentially doing a fly sparge, leaching out almost every last drop of sugar in that grain. Works for me. I need to readjust the gap on my mill again because I actually don't know if I like getting 90+% efficiency. The theory is that this waters down the malt flavor. Those are some more experiments I need to run......

Dave "This is grain, which any fool can eat, but for which the Lord intended a more divine means of consumption. Let us give praise to our Maker, and glory to His bounty, by learning about... BEER!" - Friar Tuck (Robin Hood - Prince of Thieves)

Steve Ruch
Several yers ago I went down

Several yers ago I went down to a 45 minute mash and boil with no decline in quality.

Steve
"Remember, I'm pullin' for ya: we're all in this together" Red Green