About a year ago, I took three samples of a very nice Guat, and put them into storage three different ways. One sample was held in a cloth bag, along with a piece of burlap, and put into the bottom file cabinet drawer in the office. The second sample was also put into this drawer, but was sealed inside an air tight mylar bag. The third sample was held in the freezer, inside of the same type of mylar bag. For a bit more info, check out the blog post from a few weeks ago.
I opened the samples up yesterday, and the first thing I did was to take a close look at the green. I expected to see paler color in the burlap sample, but there was no difference that I could notice. We also tracked down a small amount of the same coffee, Finca Agua Tibia from Fraijanes, from this year's harvest. There were some significant differences in appearance between the '08 and '09 lots.
The color of the fresh harvest was a bit of a deeper green, but it was a very subtle difference. The bean sizes and shapes, however, had obvious variation. This Finca is planted with Bourbon and very old Typica trees. Bourbon seeds are typically compact, somewhat spherical, without the usual elongation found in the larger Typica seeds. In many multi-varietal coffees, its pretty easy to separate out the beans from the various cultivars, especially when it is a simple blend of Bourbon and Typica. Such is the case with Finca Agua Tibia.
The seeds from the '09 harvest looked generally smaller, and upon close inspection, it looks like Bourbon has maybe taken a greater percentage. This is purely speculation, but it is certainly possible that some new Bourbon plantings have come into bearing this year, or it could be the result of imperfect homogenization during pre-export blending. In any case, the past crop samples have a much greater percentage of elongated Typica looking seeds, while the new crop looks to have more Bourbon.
All of the samples conformed to a very similar roast profile. The past crop burlap sample took a bit less heat than the others, indicative of lower moisture content. When I repeat this experiment, I plan to weigh the samples before and after storage with a gram scale capable of measuring .1 gram or better, to get a good estimate of moisture loss during storage.
We cupped blind, of course, and the results didn't present much of a surprise. Out of the past crop samples, we all preferred the mylar samples over the burlap, and the frozen sample was ever so slightly better than the regular mylar bag. I scored the frozen sample 1 point higher than the unfrozen (from the acidity category) and the burlap sample 3 points lower. I guess what did surprise me a bit was that the burlap sample didn't score lower. I've tasted many fresher samples with more of a "past crop" flavor. This Guat held up pretty well.
Between the frozen '08 and the fresh '09, we all really preferred the new crop. It was sweeter, juicier, and more powerful; I gave it an 89. It wouldn't be fair to draw any conclusions regarding storage from this; there are just too many factors that can influence the way a coffee tastes from year to year. It might be possible that freshness was the reason we liked it so much better, but it could also be harvest conditions, fermentation time, blend of varieties, etc... We'll never know for sure, but it was fun to do a vertical cupping.
All in all, it was a bit of an anti-climactic finish to a year long experiment. It proved exactly what we knew it would prove, and it reinforced our reasons for storing all of our coffees in air tight bags. If we ever need to hold a coffee for a year (we probably won't) its nice to know that freezing can be beneficial, but in the short amount of time it takes us to sell out of a coffee, I don't think it would offer us any benefit right now.
I do plan to try this one again, but with a much different coffee. Dense coffees (like a high grown Guat) hold up much better in storage, than say, a soft Brasil. Actually, I think it would be nice to taste a variety of coffees stored in multiple ways, to see what types are most vulnerable to age detioration. This experiment has also had me thinking how fun it would be to keep a frozen “library” of all of our coffees for later tasting. I'd love to go back and taste some of the coffees in my memory from years ago. I'd love to see how my own taste preferences have changed, and (hopefully) how general quality has trended upwards every year.
More experiments to come...
-Jon