I know this has been hashed around on CG with many opinions expressed. I prefer to get my data from HB, less volume and more substance. But on to the question at hand.

Being a home roaster, I spend most of my home roasting time searching for that perfect bean for the perfect blend. Knowing that greens are an agricultural product and subject to change from year to year and lot to lot, once I find a bean that hits my fancy I like to order a stock.

To date, I have followed the common belief that greens should be stored in a cool, dry, dark place. I keep them in a cupboard in cotton bags to allow for some circulation, let the beans breath. Lately I have seen quite a few indications that the new preferred storage method (a 'stock' is about one years worth) for long-term storage is to freeze the greens.

What say the bean gods?

George Howell freezes his greens, and Sivetz recommends it. I recall Mike McGinness did a controlled experiment and concluded the technique had merit.

On the downside, I've heard anecdotal reports of frozen beans aging must faster post-roast than their unfrozen equivalents.

The theoretical objection to freezing greens (as opposed to roasted coffee) is that they contain about 10% to 15% water. This water will crystallize when frozen and damage the cell walls. I have no way to judge this.

another_jim wrote:George Howell freezes his greens, and Sivetz recommends it. I recall Mike McGinness did a controlled experiment and concluded the technique had merit.

On the downside, I've heard anecdotal reports of frozen beans aging must faster post-roast than their unfrozen equivalents.

The theoretical objection to freezing greens (as opposed to roasted coffee) is that they contain about 10% to 15% water. This water will crystallize when frozen and damage the cell walls. I have no way to judge this.

That's a negative. I vacuum seal greens at in cool room temperature, not frozen. My theory was/is closest to being still in parchment, keeps any and all odor contamination away, and keeps moisture content stable. Did a 4 year greens vac storage test. (Costa Rican La Minita from SM was the control green.) The 1 year vac sealed actually out cupped the current crop, this was Tom's rating.

The fresher the greens the longer they'll be good vac stored. I've had a particular two year vac sealed Kona green, obtained while in Hawaii at the Estate right from milling to green, be better than a dozen other current crop Kona including that years Cupping Competition winner. Three years starts being noticably off. Four years toss it. Greens obtained normal channels 1 to 2 years max since they've already been out of parchment quite some time traveling here and there before we get it. Again, this is vacuum sealed but but not frozen. I vacuum seal all my greens as soon as I receive them regardless the source.

Roasted coffee stores well vacuum sealed and frozen for emergencies or to be waiting returning from vacation etc. Tom (of SM) test some 6 months frozen with positive results. When using only take out what you'll immediately grind, immediately and re-vac and back to freezer. (Sivetz is/was a big proponent of freezing hermetically sealed roasts. Don't recall him ever freezing greens though.)

My own very humble opinion is that anything I've tried, be it meat or vegetable, has not tasted as good after being frozen and thawed so I don't feel that coffee would be any different. I just can't see how freezing would not change something if even in a small way. I know that some very respected individuals have been doing this with good results but I believe one of them is freezing to -40*. I could never duplicate this at home.
My unrefined palate probably couldn't detect any change freezing might cause but using that same reasoning I probably can't tell any difference in the flavor of green stored under normal conditions for a reasonable period of time. I know that so far I haven't seen any change in the beans I've had for nearly a year so I'll keep storing them as I have been.

miKe mcKoffee wrote:That's a negative. I vacuum seal greens at in cool room temperature, not frozen. ...

Oops, remembered it wrong. I did remember correctly that you did some extensive testing on greens storage, and should be considered a maven on the topic.

another_jim wrote:The theoretical objection to freezing greens (as opposed to roasted coffee) is that they contain about 10% to 15% water. This water will crystallize when frozen and damage the cell walls. I have no way to judge this.

Probably the only way to judge it is with blind testing between "frozen" beans and never-frozen beans. It's not clear whether low temp storage will make any difference, since:

1. a good portion of the water (1/2 to 1/3, according to Illy) is bound or weakly bound inside the beans, so it may never freeze, and
2. the cell walls are blown all to hell in roasting anyway. (Obviously, if they're "pre-blown all to hell," it may affect the roast negatively).

miKe mcKoffee wrote:Roasted coffee stores well vacuum sealed and frozen for emergencies or to be waiting returning from vacation etc. Tom (of SM) test some 6 months frozen with positive results.

I don't doubt the efficacy of sealing and freezing, but wonder about the vacuum processing. If you pull too high a vacuum you'll certainly strip off desirable volatiles. A gas-flushing process that used low intensity vacuuming might be best.

AndyS wrote:I don't doubt the efficacy of sealing and freezing, but wonder about the vacuum processing. If you pull too high a vacuum you'll certainly strip off desirable volatiles. A gas-flushing process that used low intensity vacuuming might be best.

Yes I've heard the theory vacuuming roasted coffee beans sucks out the volatiles. Yet roasts mason jar FoodSaver vacuum sealed directly from cooling and four to six days vacuum rested served to an advanced cupping palate like Tom Owens suggests otherwise. I've done so on multiple occasions.

Buy smaller amounts -- enjoy the fleeting, ever-changing, seasonal reality of an agricultural product.

Respect.

malachi wrote:Buy smaller amounts -- enjoy the fleeting, ever-changing, seasonal reality of an agricultural product.

Respect.

After doing that four year greens vac storage test that's exactly what I've done. At that time greens stash had surpassed 250#, about two years supply or a bit more. Since doing the test I've reduced stash down to a current managable 108# right in my 100# target years supply. That's with adding about 50# this year. Goal being running out of any particular varietal just as the new crop coming in. Yet I'll still go through the hassle (and additional expense) of vacuum bag sealing the greens so 11 to 12 months after getting them as they're running out they'll be as fresh as possible.