Does depth of roast have an effect on shelf life? Do light roasts fare differently in the bag than dark roasts?

Staling has one thing in common with roasting -- the lighter flavors on the flavor wheel tend to disappear faster in both processes. So my rough feel is that roasted beans get "darker" as they age, and that light roasts survive a bit longer than dark roasts.

I'm starting a list of potential espresso lab experiments for our regular Friday get-together and a comparison of "staling" of a lighter versus darker roast might be interesting. Intuitively I would expect the lighter roast to suffer more quickly because it's got more to lose in the first place. Then again, it depends whether you are defining "shelf life" as a measure of the coffee's original qualities or simply whether it is drinkable.

I've been under the impression that one of Starbuck's successful business practices was to use darker roasted coffees because they lasted longer, or at least didn't suffer as much sitting around for longer periods. 'Course it could just be the 24 ounce drinks of milk, chocolate and caramel syrups .

jesawdy wrote:I've been under the impression that one of Starbuck's successful business practices was to use darker roasted coffees because they lasted longer, or at least didn't suffer as much sitting around for longer periods. 'Course it could just be the 24 ounce drinks of milk, chocolate and caramel syrups .

I think the darker roast will stale quicker, the oils close to and on the surface encouraging rancidity. Starbucks dark roast tastes of the roaster not the bean and probably seems to keep well only because it ceases to taste of anything remotely resembling coffee from the day it's roasted (or cremated). I have seen the UK starbucks beans in the grinder and if mine roasted that dark, they would be in the bin.

But really dark or light, they have all gone within 4 to 6 weeks......what remains is the belief of many of the commercial boys, that coffee is good for a year or two after roasting

jesawdy wrote:...one of Starbuck's successful business practices...

was to convince yuppies to pay exhorbitant prices for dirty milk.

HB wrote:I'm starting a list of potential espresso lab experiments for our regular Friday get-together and a comparison of "staling" of a lighter versus darker roast might be interesting. Intuitively I would expect the lighter roast to suffer more quickly because it's got more to lose in the first place. Then again, it depends whether you are defining "shelf life" as a measure of the coffee's original qualities or simply whether it is drinkable.

That's another way of looking at it -- dark roasts are already stale ("not as much to lose"), and just stay that way.

I guess one would have to define things carefully for the test.

-- One possibility, Dan, is to have the staled coffee, say 3 to 4 weeks old, and the same coffee roasted fresh, and compare by how much the score goes down. I have no guesses for this test.
-- The other possibility is to just check how much one likes the two coffees. This is the possibility I was thinking of, that light roasts stay "likable" longer. But thinking about it some more; this is a very hard notion to operationalize into a testable form. It's obvious that any test has to be a comparison of the staled coffees to a fresh roasted control sample.

Ukers, back in the 1920s, did a truly elegant version of this experiment. He let a coffee sample stale for a year (i.e. it was totally and terminally stale). He then did a roast and let it stale over the course of a few months. Each week he mixed a fresh roast and the totally stale coffee until it cupped the same as the aging sample. The ratio of fresh to total stale was a measure of how stale the aging sample was that week. It takes a lot of planning and coffee to do this, and he only did one roast of one coffee; but it is a very convincing experiment.

HB wrote:I'm starting a list of potential espresso lab experiments for our regular Friday get-together and a comparison of "staling" of a lighter versus darker roast might be interesting. Intuitively I would expect the lighter roast to suffer more quickly because it's got more to lose in the first place. Then again, it depends whether you are defining "shelf life" as a measure of the coffee's original qualities or simply whether it is drinkable.

It is rare that coffee gets old in my house. I try to buy 12oz bags or 8oz samplers, though I do buy the occasional pound bag. When the coffee does go off, it is almost always the pound bags that do. Then, there is no longer any sweet spot to be found on the grind. No matter what grind and tamp adjustments are made, the extraction stalls, dribbles, or gushes, but never flows smoothly as it should. The crema becomes little more than a slick on the surface. So I would define 'shelf-life' as the period of time during which the coffee (stored in its retail bag properly sealed and opened briefly twice a day) remains capable of producing a beverage that meets the minimum definition of espresso: it should still produce 10% crema by volume, and it should be possible to achieve a 20-30 second flow with a cake of the coffee when the brew pressure is anywhere between 6 and 9 bar.

Regards
Timo

P.S. I would like roasters to offer 8oz bags as a matter of course. Intelligentsia offers some coffees in this size. Soho will create 8oz samplers if the original is available in 16oz. Paradise offer 7oz samplers. These smaller bags are good for freshness. Other roasters may offer them as well. This smaller size adds a little to the cost of the coffee, but the additional cost, even if borne 100% by the customer, would be offset by reduced wastage and optimal enjoyment of the coffee after the bag is open.

I try to time my roasted espresso orders so that nothing gets too old, but it does happen. With that said, my experience is that lighter roasted espressos do not age as gracefully as darker. For example, Redline is good for a week after opening and then it just 'peters out'; SM blends usually last 2 weeks and sometimes are still tasty at 3 weeks. I could list other coffees, but that has been the general observation over the past few years (mostly one pound bags; 8 oz. bags might be smarter).

jffhn wrote:2 weeks...
3 weeks...

Yikes!

RoT:
Light roast days 4-8
Dark roast days 3-6

What have I been missing?