Bad batch of malt?

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BandonBrewingCo

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Hi,

2 brews I've now done with the same bag of pre-crushed pilsner have come out 33% under the mark extraction wise, even though i mashed in at a low temp and always up until now hit my numbers (and have done previously with 95% pilsner malt).

It's from the same crowd as usual and the crush didn't look too coarse. The iodine test came out fine.

Is it possible that the malt was not malted properly?

The malt had been crushed in July of this year, but had been sealed until recently. I've stored it like I always store my grains and have often used "old" grains without any problem.
 

LarMoeCur

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Have you tasted the malt? Stale malt will taste like old bread or old crackers. It will also lose a significant amount of diastatic power. 5 months is a long time to store crushed malt. I'd throw it away and get some fresh for the next batch.
 

SoCal-Doug

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Aged crushed grains are a crapshoot. Good storage without oxygen, you might be fine (or not). Like anything else made with grains (breads, cereals, etc), time, humidity and oxygen is your enemy. Nature designed them to last just through a dormant season, whole. Once you crush them, you have violated the natural protective layers.

Maybe consider storing the grains whole and investing in a mill (I know... ouch). Fresh is always best, for a multitude of chemical, biological and flavor reasons.
 

RM-MN

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Hi,

2 brews I've now done with the same bag of pre-crushed pilsner have come out 33% under the mark extraction wise, even though i mashed in at a low temp and always up until now hit my numbers (and have done previously with 95% pilsner malt).

It's from the same crowd as usual and the crush didn't look too coarse. The iodine test came out fine.

Is it possible that the malt was not malted properly?

The malt had been crushed in July of this year, but had been sealed until recently. I've stored it like I always store my grains and have often used "old" grains without any problem.
I'd suspect the crush of the grain is more likely the culprit. It doesn't take much change in the crush to change the mash efficiency, hardly enough to see.

One way to find out is to make another batch but instead of your usual mash tun, get a nylon mesh bag (paint strainer bag works fine) and use a blender to turn that milled grain into near flour. If you still get poor mash efficiency, you have a grain problem. I'd probably do a half size batch to simplify the test.
 
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BandonBrewingCo

BandonBrewingCo

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Have you tasted the malt? Stale malt will taste like old bread or old crackers. It will also lose a significant amount of diastatic power. 5 months is a long time to store crushed malt. I'd throw it away and get some fresh for the next batch.
I wasn't aware of that. I tasted the malts and they tasted flat.

How low did you mash and how accurate is you thermometer?
20 mins at 55C, an hour at 63C, mash out at 75. I use a recirc pump with a thermometer just before the pump. It's a DS18B20 which is feeding into CraftBeerPi so pretty accurate. I've checked it against a kitchen probe thermometer and they match up.

Aged crushed grains are a crapshoot. Good storage without oxygen, you might be fine (or not). Like anything else made with grains (breads, cereals, etc), time, humidity and oxygen is your enemy. Nature designed them to last just through a dormant season, whole. Once you crush them, you have violated the natural protective layers.

Maybe consider storing the grains whole and investing in a mill (I know... ouch). Fresh is always best, for a multitude of chemical, biological and flavor reasons.
Ya, it was the last of them thankfully. I'll keep my orders small from now on and take the hit on delivery. I also noted the best before was approx 3 months after the packaging date. I'll have to check is that for all grains or did I get the last of an old batch of pilsner perhaps. If so, I'll be moving to a new supplier.
 
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