Impact of Crushed Malt Age on Beer Quality

drew's picture

A number of homebrewers, even advanced all-grain veterans like Denny, don't own a mill at home. Many depend on the mill at their homebrew supplier. (Denny uses a friend's mill.) They buy their grains crushed courtesy of their store of choice. Naturally, life happens after we've crushed our malt and everyone is afraid of the ticking time bomb that is crushed malt. Naturally, since we're homebrewers we don't want to waste our money ingredients if we don't have to - so can we use that pre-crushed malt? The belief is that malt, once crushed, is prone to rapid staling leading to reduced quality brews. Lots of various reasons but ultimately the cause is cracked malt is prone to moisture absorption and oxidation. How long is too long? At what point do you need to chuck the malt and start fresh or at least get your brewing act together. (See this is why Drew has a mill - he can't get his act together to depend on getting to crushed malt in time)


Proposed By: 


Does cracked malt that's been left to sit for a month produced a noticeably different beer than freshly cracked malt?


There will be a qualitative noticeable difference between the beer produced with freshly cracked malt and aged cracked malt with the pre-cracked malt batch showing worse quality

Brewing Sessions Needed: 



Special Equipment/Process: 

  • This requires some foreplanning and two sessions - so bust out your control factors!
  • Buy two batches worth of malt for the target recipe
  • Crush one batch 1 month ahead of the brew day
  • Crush the other batch on brew day
  • Brew these beers as close together as possible to reduce other factors (e.g. weather)

Special Observations: 

  • Note any differences between the two brews in terms of gravity, clarity and color. Part of the theory is that staled malt will produce darker, less clear beer.
  • Note the weather during the storage period - temps/humidity/rain/snow

Experimental Procedure: 

  1. Purchase two batches of the target recipe - Experimental Wheat.
  2. One (1) month ahead of your brew day, crush one batch of malt and store in a paper sack in your normal brewing space
  3. After aging, brew the recipe, following all relevant instructions.
  4. In a timely fashion, brew the recipe again using freshly crushed malt
  5. Ferment both batches in the same space and under the same conditions, especially temperature. Match the fermenters and other equpment.
  6. After fermentation subsides, record the length of fermentation and the final gravities.
  7. Package the two beers in exactly the same fashion. (Bottle primed with sugar, kegs and force carbonated, etc) - Record packaging methodology
  8. Perform a triangle test and record the results
  9. Ask the testers for their observations on the samples. DO NOT Reveal the Difference between the samples
  10. Discuss the results and record any further observations

Recipe Link:

Further Exploration Paths: 

What changes if the "aging" time of the pre-crushed malt is reduced
Does the means of storing the malt alter aging effects (e.g. plastic zip bag, vacuum packed, air tight storage container, humid basement, cold area, hot area)
blbvtec's picture
Aged Crushed Malt

I don't think you'll find much difference with a month. I did brew a batch earlier this year with precrushed malt and it was awful (dry 70F for several months in MoreBeer sealed bags).

drew's picture
It's a good point, I think we

It's a good point, I think we'll have to revisit this one a few times because I also suspect it will be time of year/weather/region dependent.) I suspect I could get away with it more in California than someone in Florida.

Brandon.pesavento's picture
Aged crushed malts

Also style could hide true results. I think that if we brewed a light hoppy pale s.m.a.s.h. We could get better results.

^v^ Brandon ^v^

CA_Mouse's picture
Aged crushed malts

I think this would work better with grain from the same bag and a minimum of 60 days between milling. Grains would need to be stored in identical containers under identical conditions.

Personally, I think this would be more of an issue in the Pacific Northwest and the South East where there are such extremes in humidity and temperature. Like Drew, I could probably mill an entire 50# bag and use it over a three month period with little, to no difference.



CA_Mouse's picture
What about doing an American

What about doing an American Wheat? These are fairly light and oxidized wheat may be more detectable to the palate. Perhaps something on the lines of 65% 2-Row and 35% Wheat using a Chico strain?


jasonclick's picture

where is the recipe for this? I thought i saw it once.

Reduced Variables

Unfortunately I have to believe the "in a paper bag in your normal brewing space" is going to encourage quite a few random results in an experiment like this. That said, if the target conclusion is "it completely depends on your location" then it is probably a good design.

One option might be to look at centralizing the aged malt source. It is very likely that you could get an online source to do this experiment for you.

Just as an example, Northern Brewer could agree to create a "pre-order" item for one-time use. Each of us gives them the $30 during the pre-order period and NB delivers the grain to us later.

Then they could mill the first half of grain and store it somewhere for a couple months in an open but controlled bag, and mill the second half all on the same day they package for shipment. The only real variable would be transit time between NB and the testers, but that variable is one that every brewer fights with on every batch of mail-order.

Plus it gives the site an opportunity to engage a sponsor somewhere.

I'm sure the guys at Yakima Valley Hops would be willing to do something like this, they are super friendly every time I talk to them, and they also Mill and Vacuum Pack grains on the day of shipment, so the fresh grains should have their best shot at "freshness".

nicki0329's picture

If possible to coordinate in this way, I think BeardedBrews suggestion of working with an online retailer to help control the aging, milling and storage variable for this experiment is a great idea. Is this something we can consider? If so, I'm in! Nicki

CA_Mouse's picture
Did we ever decide on the

Did we ever decide on the recipe for this one? I thought that there had been one, but I couldn't find it a second time.



CA_Mouse's picture
Found it right after posting!

Found it right after posting! Guess I was the final fool for the day! LOL



nicki0329's picture
Recipe Question

Just wondering if we need/should be adding rice hulls w/wheat malt making up 50% of the grist. If so, how much, for consistency purposes? Thanks! Nicki

drew's picture
I think it's going to depend

I think it's going to depend on what you need for your system. I don't need them if I'm doing up to around 65%, but given their minimal impact flavorwise, I say use them if you need them!

nicki0329's picture
I haven't ventured much into

I haven't ventured much into wheat territory so I have no idea how things will go. Gonna live on the edge and try without, cursing all the way if things go awry. 

drew's picture
I have faith in your

I have faith in your abilities to live on the raggedy edge. :)

jpseattle's picture
Old malt - an accidental experment

Thought I'd share an unscientific outcome.  Without a designed experiment, it was informative enough that I can recommend NOT doing this on purpose. 

A dead PID in my electric controller caused me to do this "experiment" inadvertently.  After buying and milling malt at my local shop, I got home to find that my brewery was offline.  The malt was left in a paper bag in a dry 60F Seattle basement for 10 weeks.  After the adventure of getting the controller fixed, I decided to use the old malt, because "why not?".  It's still in the fermenter, but the gravity was massively off on a known recipe.  The 1.070 DIPA was only 1.045 at the end of boil-down.  I control the water profile, ph, and use an electric recirculating mash to control mash temp (hence, the dead PID.)  The only difference that I'm aware of was the age of the crushed malt. 

Because there will be no A/B comparison, and because this recipe uses a lot of late and dry hopping, I would dismiss any idea of discerning flavor differences.  The malt bill was 60% 2-row, 38% Golden Promise, and 2% Crystal 10, if that matters to anyone.  This isn't my go-to recipe for personal consumption, but more of request for IPA-head friends.  If you wanted to do this experiment to test for flavor differences, an english bitter would be a better choice.

Just seeing the magnitude of the gravity miss, "use fresh malt" seems like a pretty safe conclusion from my incident.