Ramble On

Tuesday, August 25, 2015

The 2015 Hops Harvest @hawksbillhops - Part 5

Here's a tray of Cascades, ready for sampling and
packaging - bowl and scale in the foreground.
Thanks to David Sours for this photo -
working late into the evening to package
our first batch of dried hops!

By the second day of drying and packaging, the activities had settled into a routine.  Once we loaded the HOP-N-ATOR 4000 with fresh wet hop cones, and ensured they were distributed evenly, we closed up the machine and turned on the heater and fans to get things going.  (Our first batch had taken 30+ hours to dry, so we improved the machine with a little space heater - we'll probably upgrade this part of the operation next year!)

Here's a few Cascade cones that I tore apart for
inspection after they'd been dried.
The goal of drying the cones - or Oasting, as it is traditionally called - is to reduce the moisture in the raw plants so that they become more stable and easier to store and handle.  The industry standard for this is around 8% moisture, so if the assumption is the plant materials are 10% of the originally weight, you're after getting the wet cones down to 18% or so of their original weight.

This seemed to me to be an excellent application of those operations management classes I loved in business school...in fact I was a tutor for this subject!  So I devised a "statistical process control" method for taking periodic samples of the hops to determine our drying progress.  I developed a formula for setting a target weight (there was an error in the one I used, so we didn't get all the way down to 18% - plus the lab informed me that no one in Virginia was quite getting there, likely due to our humid climate).

I used the bowl shown in one of the photos as the standard volume to weigh - setting the original weight with a sample from each of the HOP-N-ATOR 4000 trays.  After averaging this, I calculated a target rate by using an interval formula (note that this is where the error in my calculations crept in).  Then I pulled a sample or two from each of the trays every few hours to measure progress, and to estimate the remaining drying time.

This wheat beer from @boulevard_beer became my
refreshment of choice during hops drying.  Our operation is
too small to supply them, though (I asked).
This worked well and added some much needed predictability to the process.  Even though we didn't quite get to the 18% weight target, we did manage to get the Cascades into the range of 26-28% which is pretty close.  It's enough to stabilize the hops, and now that the harvest is a few weeks behind us we've gone ahead and moved them into the freezer as well.

The next post will be the final in this series.  I'll post the alphas and betas we achieved on our inaugural crop, talk about yields, and also will discuss some of the improvements we have in mind for next year.

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