You may want to check out the latest episode of Basic Brewing Radio. Chris Colby and I discuss the results of a listener’s experiment which targeted the question: “How long do you have to mash”.
Kai, can you summarize the results?
Kai, I listened and liked it. I have done some shorter mashes in the past, but 60 minutes is my norm now, except if I am doing a step mash or decoction. This supports what some, including Fred in the BJCP class, have said - if it passes the conversion test, that just means there are no starches, and you can get more fermentable sugars by mashing longer.
I’ll try to do that later tonight. This topic is something that comes up once in a while in discussion.
Kai
Thanks. Based on posts here, I gather it’s pretty much like I’ve always thought.
I’ll be sure to give it a listen.
My own answer, based on my own experiments, is 40 minutes. Why? A 30-minute mash is long enough sometimes, but not always, and 90 minutes (or even 60!) is rarely necessary. But 40 minutes seems to be the sweet spot for my system for most styles.
It will be interesting to hear what other experiments have come up with. I hope the answer isn’t too wishy-washy.
EDIT: Just wanted to add that my limitation is based on ATTENUATION, NOT CONVERSION. You can mash for as little as 15 to 20 minutes and get decent conversion, but your attenuation is going to suck and you’ll end up with a thick syrupy beer post-fermentation.
Sounds like James Spencer’s results are similar to mine. 30 minutes was enough for him, but there was still some starch in there, which, after 60 minutes was gone. I wish they would have done more experiments in between 30 and 60 as I have.
IF ya’ll are interested:
- I am a batch sparger. I also BIAB (more often these days).
- I always mash at 148 to 152 F.
- I always mash at a water to grain ratio of 1.25 to 1.45 qts/lb.
- I always stir my mash every 10 to 15 minutes to assure even temperature distribution.
- I always mashout but never hit 170 F. The highest I ever get is about 165 F, and that is rare – usually it’s about 155 to 160 F.
Take it for whatever it’s worth (perhaps less than 2 cents).
Finally some time to follow up on this.
Charles, a listener, and James did experiments where they brewed the same beer with a 10 min, 30 min and 60 min mash. This was sparked by Chris Colby’s comments on an earlier show that indicated that with modern malts a mash converts in as little as 10-15 min and that we don’t need to mash for 60 min.
The result was that 10 min is way to short to mash. The efficiency of this batch suffered greatly. Interestingly enough it resulted in the highest attenuation in Charle’s experiments but due to the lower efficiency the total amount of fermentable sugars produced was lower than for the other two mashes. Taste wise, Charle’s 10 min mash beer tasted the worst. It was rather thin despite having had an OG of 1.063. The others tasted better and I don’t remember if the 30 or 60 min mash beer ended up being the best.
I don’t remember if James made drinkable beers or if he simply used bread yeast to test the wort fermentability.
The conclusion is that even though todays malts are said to convert in 10-15 min (which is a number that comes from a lab test) sufficiently long mashing times are needed to achieve the desired attenuation, efficiency and flavor profile of the beer. Even a negative iodine test doesn’t mean that mashing is complete.
Kai
I’ve found I get slightly better efficiency and slightly better fermentability by using mashes longer than 60 min. I admit to never really having tried a shorter than 60 min. mash, though, so there may well be little difference between 40 min. and 60 min. I use a bit wider temp range than Dave, usually about 1.65 qt./lb. and never stir the mash. I kinda wish they would have done a longer than 60 min. mash for comparison.
Is james Spencer on this forum? If he is he’s under a pseudonym?
Good program on BBR Kai!
I listened to the show today–really good. The 30-minute and 60-minute beers were drinkable, and the 60-minute mash tasted the best.
I often wonder what the upper limits of mashing are. I also liked Kai’s point (or what I thought I heard was his point) that what people think of as the benefits of mashing-out may really be due to a longer mash. One thing this podcast will inspire me to do is set my timer and stir every 15 minutes.
I agree, and I also think the temp raise helps, too.
I haven’t listened yet, but I never stir during the mash. What’s the supposed benefit?
I’d have to listen again since my attention faded in and out (I was playing this podcast through my car stereo, at one point barely dodging a truck suddenly backing into an active lane of big-city traffic), and if the answer was scientific I probably tuned it out anyway, but I’m guessing stirring is saturation insurance–like the same reason you gently mix a cake batter for a minute or two after adding the last ingredients.
I’ve been reluctant to stir because I don’t want to incur temperature loss. But I’d at least try it to see if a known recipe could pick up some efficiency. Three “stirs” with a warm spoon at 15, 30, and 45, just to see what happens. (Though since I don’t crush my own grain I lose an important variable.)
Of course, efforts to boost my efficiency will be unnecessary when I get my blue mash tun.
Yeah, the blue ones go to 11! 
FWIW, I never stir my mash and get mash efficiencies in the 90s. So I have to admit it seems unnecessary to me. If you try it, please let us know if you fond any benefits!
Since I started doing mashout or no-sparge after a 90min mash I get a bump in efficiency but the wort isn’t as fermentable because what was finishing at 1.010 will come out 1.015. Part of me likes the efficiency but I don’t always want that kind of FG.
I usually let the mash go for 90min, it doesn’t really hurt anything as long as you have the time. I also feel like the flavor compounds (Maillard compounds) might steep out better with a longer soak. Its like making tea, you can get color with a teabag in a minute but it tastes more full after five.
That’s really strange. That regimen gives me a much more fermentable wort.
Yeah, I can’t think of anything that would make wort less fermentable after more time. For the one that finished at 1.015 instead of 1.010, what was the OG and change in efficiency? I suspect it was something else that caused it to finish high, not the longer mash.
I’m normally mashing at 150F and the temp may drop a few degrees over the course of an hour to 90min. My theory is that the short (10-15min) rest favoring alpha amylase is chunking up new starch that doesn’t have time to be chewed into mono/disaccharides before I run off and boil. Its just a correlation though, it could also be the cooler ferm temps in my basement. Plus some of my results are coming from altbier ferms @60F and I don’t have a ton of experience with WY1007.
Do it a few more times and let us know if there is a definite trend. I suspect it’s the other things(new recipe, cooler ferm temps), but you never know.
Lennie’s theory is what I would be suggesting as well. If you get a serious efficiency bump from a “mash-out”, or dextrinization rest" it will come mostly in the form of unfermentable sugars and shift the sugar profile in the wort toward being less fermentable, If you were to test fermentability before and after the dextrinization rest you would notice a decrease in fermentability but if you determine the actual amount of fermentable sugars you’ll see that it did not decrease. It may have increase a little, but not as much as the unfermentable sugars.
If you don’t get an efficiency boost from this rest you most likely converted all the starched before that rest and there will not be an increase in un-fermentable sugars. Just a slight increase in fermentable sugars wich does show up as slightly better attenuatuion.
Kai