Background: My co-brewer (ScottyG) and I recently brewed our first all-grain in a converted Coleman cooler. We have over sixty batches of extract under our belts and have even made a few hard ciders and a batch of mead. I freely admit, we are a bit late in getting around to going all-grain, but we’ve learned a LOT in our 60+ batches of extract+steeping grains.
We didn’t have high expectations for the first batch. We did some experiments to approximate temperature drops in the cooler (surprisingly little) and made sure we were using proper procedure. (following via ScottyG) *We used 10# of grain (9# Marris Otter, 1# Simpson's Dark Crystal) and 1.5 qt/lb for both mashing and sparging. Doughed in at 153, added 1 pint of boiling water. We let it rest for 60 min and the final temp was 149 F. Sparge water was 168 F, and we let it soak for 20 minutes before draining.
We did not: 1) Test pH 2) Test with iodine
First runnings were 2.4 gal @ 1.054, second runnings were 4.6 gal @ 1.012. Final was 7.1 gal @ 1.026 for an efficiency of 50%.* Much lower than we had expected, much lower than our software or hand calculations projected. The first running was about the SG we expected from the second.
We used some pre-crushed grain that was about a year old. (crushed at Northern Brewer about a year ago). It was from a kit a friend bought for us to make and had mistakenly got all-grain. We are reasonably certain that our troubles come from old grain, crushed a year ago. (BTW, we augmented with some extract to bring the resulting beer up to an acceptable SG. (Yay, it’s gonna be a beer!)
Now after all that setup, here’s the question:
What effect does the age of the grain have on the amount of fermentables you can mash out of it? Does the crush decrease the “freshness window?”
TL;DR What effect does old grain have, especially if it was crushed in the past.